/* ============================================================
   Cryptography Explorer — house style
   Adapted from the space / spectrum teaching aids (see reference/STYLE_GUIDE.md).
   Dark-only. Brand palette shared with the whole sean.theinformed.org family.
   Semantic color roles used throughout the labs:
     cyan  = public values      amber = secret values
     coral = danger / destroyed  mint  = success / verified
   ============================================================ */

:root {
  color-scheme: dark;
  --void: #02070c;
  --surface: #020a10;
  --surface-2: #05131d;
  --surface-3: #09202b;
  --line: rgba(132, 194, 214, 0.18);
  --line-strong: rgba(132, 220, 235, 0.34);
  --text: #edf8fb;
  --muted: #8da8b3;
  --quiet: #668794;
  --cyan: #29d4e3;
  --cyan-bright: #5ce8f1;
  --amber: #f5c96a;
  --coral: #ff7b78;
  --violet: #a98cff;
  --mint: #76e6a5;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --topbar-height: 68px;
  --shadow-md: 0 12px 30px rgba(0, 7, 13, 0.28);
  --ease-out: cubic-bezier(0.2, 0.8, 0.2, 1);
  --mono: "IBM Plex Mono", ui-monospace, "Cascadia Mono", Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 14% -12%, rgba(24, 127, 151, 0.2), transparent 38%),
    var(--void);
  color: var(--text);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  line-height: 1.55;
}

/* Base style for links in body copy (intro paragraphs, dialog text).
   Components (.header-button, .view-tab, .try-link, …) restyle themselves;
   without this, bare links fall back to browser blue/purple visited colors. */
p a {
  color: var(--cyan-bright);
  text-decoration: none;
  border-bottom: 1px solid rgba(92, 232, 241, 0.35);
}

p a:hover { border-bottom-color: var(--cyan-bright); }

/* ---------- topbar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  height: var(--topbar-height);
  padding: 0 clamp(14px, 3vw, 28px);
  border-bottom: 1px solid var(--line);
  background: rgba(2, 10, 16, 0.86);
  backdrop-filter: blur(9px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: inline-flex;
  width: 38px;
  height: 38px;
  color: var(--cyan);
}

.brand-mark svg { width: 100%; height: 100%; }

.brand .eyebrow { margin: 0; }

.brand h1 {
  margin: 0;
  font-size: 1.02rem;
  font-weight: 720;
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.eyebrow {
  display: block;
  margin: 0 0 4px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  line-height: 1.2;
  text-transform: uppercase;
}

.topbar-actions { display: inline-flex; align-items: center; gap: 9px; }

.icon-button, .header-button {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 13px;
  border: 1px solid var(--line);
  border-radius: 11px;
  color: var(--text);
  background: rgba(9, 32, 43, 0.55);
  font: inherit;
  font-size: 0.82rem;
  cursor: pointer;
  text-decoration: none;
  transition: border-color 160ms var(--ease-out), background 160ms var(--ease-out);
}

.icon-button { width: 42px; padding: 0; }

.icon-button:hover, .header-button:hover { border-color: var(--line-strong); background: rgba(15, 48, 62, 0.7); }

.header-button.current { border-color: var(--line-strong); color: var(--cyan-bright); }

/* ---------- landing ---------- */
.shelf {
  max-width: 1060px;
  margin: 0 auto;
  padding: clamp(26px, 5vw, 54px) clamp(16px, 4vw, 30px) 60px;
}

.shelf-intro { max-width: 720px; }

.shelf-intro h2 {
  margin: 6px 0 12px;
  font-size: clamp(1.5rem, 3.6vw, 2.2rem);
  font-weight: 730;
  letter-spacing: -0.03em;
  line-height: 1.12;
}

.shelf-intro p { margin: 0 0 12px; color: var(--muted); font-size: 0.95rem; }

.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 18px;
  margin-top: 30px;
}

.module-card {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: linear-gradient(160deg, rgba(9, 32, 43, 0.55), rgba(2, 10, 16, 0.4));
  box-shadow: var(--shadow-md);
  color: inherit;
  text-decoration: none;
  transition: border-color 180ms var(--ease-out), transform 180ms var(--ease-out);
}

.module-card:hover { border-color: var(--line-strong); transform: translateY(-2px); }

.module-card h3 { margin: 0; font-size: 1.18rem; font-weight: 720; letter-spacing: -0.02em; }

.module-card p { margin: 0; color: var(--muted); font-size: 0.86rem; }

.module-card .card-icon { width: 44px; height: 44px; display: grid; place-items: center; color: var(--cyan); font: 600 2rem/1 var(--mono); }
.module-card .card-icon svg { width: 100%; height: 100%; }

.module-card .card-go {
  margin-top: auto;
  padding-top: 8px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.module-card.soon { opacity: 0.55; pointer-events: none; }

/* ---------- lab shell ---------- */
.page-head {
  max-width: 1240px;
  margin: 0 auto;
  padding: clamp(20px, 4vw, 36px) clamp(16px, 3vw, 28px) 6px;
}

.page-head h2 {
  margin: 4px 0 8px;
  font-size: clamp(1.4rem, 3.4vw, 2rem);
  font-weight: 730;
  letter-spacing: -0.03em;
  line-height: 1.12;
}

.page-head > p { max-width: 760px; margin: 0; color: var(--muted); font-size: 0.93rem; }

.lab {
  max-width: 1240px;
  margin: 14px auto 0;
  padding: 0 clamp(16px, 3vw, 28px) 26px;
  outline: none;
}

.lab-input {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-2);
}

.lab-input label {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.lab-input input[type="text"] {
  flex: 1 1 200px;
  min-height: 40px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  background: var(--surface);
  font-family: var(--mono);
  font-size: 0.9rem;
}

.lab-input input[type="text"]:focus { outline: none; border-color: var(--line-strong); }

.lab-input select {
  min-height: 40px;
  padding: 0 8px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  background: var(--surface);
  font-family: var(--mono);
  font-size: 0.84rem;
}

.lab-input .hint { flex-basis: 100%; margin: 0; color: var(--quiet); font-size: 0.74rem; }

.go-button {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid rgba(92, 232, 241, 0.5);
  border-radius: 10px;
  color: #001217;
  background: var(--cyan-bright);
  font: inherit;
  font-size: 0.85rem;
  font-weight: 650;
  cursor: pointer;
}

.go-button:hover { filter: brightness(1.08); }

/* Landing state: a lab page opens with just the welcome text and the input
   card. The machine (.lab-grid) stays hidden until the run starts — the lab
   JS sets body.lab-started — and then the welcome text hides instead, so the
   animations get the whole viewport. ⏮ restart returns to the landing state. */
.lab-page:not(.lab-started) .lab-grid { display: none; }
/* Same width and left edge as the welcome paragraph above it (.page-head > p
   is also capped at 760px), so the landing reads as one aligned column. */
.lab-page:not(.lab-started) .lab-input { max-width: 760px; margin: 10px 0 0; }
.lab-page.lab-started .page-head { display: none; }

.lab-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 390px);
  gap: 16px;
  margin-top: 16px;
}

.viz-panel {
  min-width: 0;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface-2);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.viz-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding: 13px 18px 10px;
  border-bottom: 1px solid var(--line);
}

.viz-head h3 { margin: 0; font-size: 1rem; font-weight: 700; letter-spacing: -0.015em; }

.viz-head .viz-sub { color: var(--quiet); font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase; }

.viz-body {
  /* Grows with the card (Sean's ask): the transport sits ABOVE the workspace,
     so expanding downward moves nothing — no nested scroll area, nothing cut
     off; the page scrolls instead. */
  min-height: 320px;
  position: relative;
  padding: 16px 18px 18px;
}

.explain-panel {
  align-self: start;
  position: sticky;
  top: calc(var(--topbar-height) + 14px);
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface-2);
  overflow: hidden;
}

.explain-head {
  padding: 12px 16px 9px;
  border-bottom: 1px solid var(--line);
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.64rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.explain-body {
  padding: 13px 16px 16px;
  max-height: min(52vh, 500px);
  overflow-y: auto;
  font-size: 0.85rem;
  color: var(--muted);
}

.explain-body h4 { margin: 0 0 8px; color: var(--text); font-size: 0.95rem; font-weight: 700; letter-spacing: -0.01em; }

.explain-body p { margin: 0 0 9px; }
.explain-body p:last-child { margin-bottom: 0; }

.explain-body code {
  padding: 1px 5px;
  border-radius: 6px;
  background: rgba(9, 32, 43, 0.8);
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.8em;
}

.explain-body .why {
  margin: 10px 0 0;
  padding: 9px 11px;
  border-left: 3px solid var(--cyan);
  border-radius: 0 8px 8px 0;
  background: rgba(24, 89, 103, 0.14);
  font-size: 0.8rem;
}

.explain-body .why.warn { border-left-color: var(--coral); background: rgba(103, 40, 38, 0.16); }
.explain-body .why.gold { border-left-color: var(--amber); background: rgba(103, 84, 34, 0.14); }

/* ---------- symbol glossary ---------- */
.sym-head {
  padding: 11px 16px 8px;
  border-top: 1px solid var(--line);
  color: var(--amber);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.sym-body {
  padding: 2px 16px 14px;
  max-height: 34vh;
  overflow-y: auto;
}

.roadmap-cast { max-height: none; padding: 4px 0 8px; }
.roadmap-cast .sym { flex: 0 0 116px; }

.sym-row {
  display: flex;
  gap: 10px;
  padding: 5px 0;
  border-bottom: 1px solid rgba(132, 194, 214, 0.08);
}

.sym-row:last-child { border-bottom: none; }

.sym {
  flex: 0 0 96px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.76rem;
  font-weight: 600;
}

.sym-def {
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.45;
}

/* collapsed symbol fold inside learn-mode demos */
.sym-fold {
  border-top: 1px solid var(--line);
}

.sym-fold summary {
  padding: 8px 15px;
  color: var(--amber);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  cursor: pointer;
  list-style-position: inside;
}

.sym-fold summary:hover { color: var(--text); }

.sym-fold .sym-body { padding: 0 15px 12px; }

/* semantic value colors */
.val { font-family: var(--mono); font-weight: 600; }
.val-pub { color: var(--cyan-bright); }
.val-sec { color: var(--amber); }
.val-danger { color: var(--coral); }
.val-ok { color: var(--mint); }

/* ---------- the ledger: the machine so far ---------- */
.ledger {
  display: none;
  padding: 8px 18px 9px;
  border-bottom: 1px solid var(--line);
  background: rgba(2, 10, 16, 0.55);
  font-family: var(--mono);
  font-size: 0.66rem;
  line-height: 1.7;
  max-height: 168px;
  overflow-y: auto;
}

.ledger.has-content { display: block; }

.led-row { display: flex; gap: 10px; align-items: baseline; }

.led-label {
  /* wide enough that no label ("padded message") ever wraps to two lines */
  flex: 0 0 104px;
  color: var(--amber);
  font-size: 0.58rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-align: right;
  white-space: nowrap;
}

.led-val { color: var(--muted); word-break: break-all; }
.led-val .msg { color: var(--cyan-bright); }
.led-val .one { color: #001217; background: var(--amber); border-radius: 2px; padding: 0 2px; font-weight: 700; }
.led-val .zero { color: var(--quiet); }
.led-val .len { color: var(--coral); }
.led-dim { color: var(--quiet); }
.led-word { color: var(--muted); }
.led-drained { color: var(--quiet); opacity: 0.4; }
.led-count { color: var(--cyan-bright); }
.led-hash { color: var(--mint); }

.led-k { display: inline; }
.led-k summary { display: inline; cursor: pointer; list-style: none; }
.led-k summary::-webkit-details-marker { display: none; }
.led-k summary:hover .led-dim { color: var(--cyan-bright); }
.led-k[open] summary .led-dim { color: var(--cyan-bright); }
.led-kfull { display: block; margin-top: 3px; word-break: normal; }

.led-regs { display: inline-flex; flex-wrap: wrap; gap: 5px; }

.led-reg {
  display: inline-flex;
  gap: 4px;
  padding: 0 5px;
  border: 1px solid var(--line);
  border-radius: 5px;
  color: var(--text);
}

.led-reg b { color: var(--cyan-bright); font-weight: 700; }

.led-reg.led-flash { animation: led-flash 700ms var(--ease-out); }

/* ---------- RSA key dock + message strip ---------- */
.key-dock .kd-keys { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; }
.key-dock .kd-label {
  color: var(--quiet);
  font-size: 0.6rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.key-dock .kd-label.kd-sec { margin-left: 14px; }
.key-dock .kd-sep { color: var(--quiet); }
.key-dock .led-reg.pub b { color: var(--cyan-bright); }
.key-dock .led-reg.sec { border-color: rgba(245, 201, 106, 0.4); }
.key-dock .led-reg.sec b { color: var(--amber); }
.key-dock .led-reg.destroyed {
  border-color: rgba(255, 123, 120, 0.4);
  color: var(--quiet);
  text-decoration: line-through;
  opacity: 0.65;
}
.key-dock .led-reg.destroyed b { color: var(--coral); }
.key-dock .led-reg.hl {
  border-color: rgba(92, 232, 241, 0.85);
  box-shadow: 0 0 12px rgba(41, 212, 227, 0.3);
}
.key-dock .led-reg.sec.hl:not(.destroyed) {
  border-color: rgba(245, 201, 106, 0.85);
  box-shadow: 0 0 12px rgba(245, 201, 106, 0.3);
}
.key-dock .kd-note { color: var(--quiet); font-size: 0.64rem; font-style: italic; }

.rsa-strip { margin: 2px 0 16px; font-family: var(--mono); }
.strip-row { display: flex; flex-wrap: wrap; gap: 5px; }
.rsa-tile {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  /* same width in both rows, so each plaintext column sits exactly above
     its ciphertext — the "this becomes that" mapping stays readable */
  min-width: 62px;
  padding: 4px 7px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface-2);
}
.rsa-tile .rt-main { font-size: 0.86rem; color: var(--text); }
.rsa-tile .rt-sub { font-size: 0.6rem; color: var(--quiet); }
.rsa-tile.done { opacity: 0.55; }
.rsa-tile.todo .rt-main { color: var(--quiet); }
.rsa-tile.current {
  border-color: rgba(92, 232, 241, 0.85);
  background: rgba(24, 89, 103, 0.42);
  box-shadow: 0 0 12px rgba(41, 212, 227, 0.25);
}
.strip-row.bot .rsa-tile.done .rt-main,
.strip-row.bot .rsa-tile.current .rt-main { color: var(--cyan-bright); }

.strip-lock {
  display: flex;
  align-items: center;
  gap: 8px;
  width: max-content;
  max-width: 100%;
  margin: 8px 0;
  padding: 6px 14px;
  border-radius: 9px;
  font-size: 0.76rem;
  color: var(--text);
}
.strip-lock.enc { border: 1px solid rgba(92, 232, 241, 0.55); background: rgba(24, 89, 103, 0.3); }
.strip-lock.dec { border: 1px solid rgba(245, 201, 106, 0.55); background: rgba(84, 66, 24, 0.25); }
.strip-lock.dec b { color: var(--amber); }
.strip-lock.enc b { color: var(--cyan-bright); }
.strip-lock .lock-arrow { color: var(--quiet); }
.strip-lock .lock-glyph { width: 16px; height: 16px; flex: 0 0 16px; }
.strip-lock.enc .lock-glyph { color: var(--cyan-bright); }
.strip-lock.dec .lock-glyph { color: var(--amber); }

/* ---------- Caesar & Vigenère ---------- */
/* letter-frequency histogram: the fingerprint that survives a shift */
.freq-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin: 10px 0; }
.freq-chart { min-width: 0; }
.freq-row { display: flex; align-items: center; gap: 7px; margin: 2px 0; font-family: var(--mono); font-size: 0.7rem; }
.freq-letter { flex: 0 0 14px; color: var(--cyan-bright); font-weight: 700; }
.freq-bar {
  height: 11px;
  border-radius: 3px;
  background: linear-gradient(90deg, rgba(41, 212, 227, 0.75), rgba(41, 212, 227, 0.35));
  min-width: 3px;
}
.freq-chart:last-child .freq-bar { background: linear-gradient(90deg, rgba(245, 201, 106, 0.75), rgba(245, 201, 106, 0.3)); }
.freq-n { color: var(--quiet); }
@media (max-width: 640px) { .freq-cols { grid-template-columns: 1fr; } }

/* the one-letter arithmetic lines inside a worksheet card */
.vig-line { margin: 4px 0; font-size: 0.98rem; }
.vig-line.vig-hot { color: var(--amber); }
.vig-key-input { max-width: 12ch; flex: 0 1 auto !important; }

/* the K fill card: all 64 constants as slot chips, landing row by row */
.k-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 6px 0 12px;
  font-family: var(--mono);
  font-size: 0.72rem;
}
.k-grid .led-reg {
  opacity: 0;
  animation: tile-in 260ms var(--ease-out) forwards;
  animation-delay: calc(var(--d, 0) * 110ms);
}

/* a value in flight from its source to where it's used */
.ghost {
  position: fixed;
  z-index: 90;
  padding: 4px 12px;
  border: 1px solid rgba(92, 232, 241, 0.85);
  border-radius: 8px;
  color: var(--cyan-bright);
  background: var(--surface-3);
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 600;
  white-space: nowrap;
  pointer-events: none;
  opacity: 1;
  box-shadow: 0 0 18px rgba(41, 212, 227, 0.35), 0 6px 18px rgba(0, 0, 0, 0.5);
  /* slow, readable flight; the chip stays solid almost the whole way and
     only fades right as it lands */
  transition: transform 1700ms cubic-bezier(0.35, 0, 0.25, 1), opacity 450ms ease 1350ms;
}

/* a ledger entry being read by the current operation */
.led-read { animation: led-read 850ms var(--ease-out); }

@keyframes led-read {
  0% { border-color: var(--amber); background: rgba(245, 201, 106, 0.28); }
  100% { border-color: var(--line); background: transparent; }
}

@keyframes led-flash {
  0% { border-color: var(--mint); background: rgba(118, 230, 165, 0.25); }
  100% { border-color: var(--line); background: transparent; }
}

/* ---------- player controls ---------- */
.player { display: flex; flex-direction: column; gap: 10px; padding: 12px 18px 16px; border-bottom: 1px solid var(--line); background: rgba(2, 10, 16, 0.5); }

.player-chips { display: flex; flex-wrap: wrap; gap: 6px; }

.chip {
  display: inline-flex;
  min-height: 26px;
  align-items: center;
  gap: 5px;
  padding: 3px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  background: rgba(17, 50, 64, 0.58);
  font: inherit;
  font-family: var(--mono);
  font-size: 0.64rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  white-space: nowrap;
  cursor: pointer;
}

.chip:hover { border-color: var(--line-strong); color: var(--text); }

.chip.active { border-color: rgba(92, 232, 241, 0.55); color: var(--cyan-bright); background: rgba(24, 89, 103, 0.4); }

.player-transport { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }

.player-transport .icon-button { width: 44px; min-height: 38px; font-size: 0.9rem; }

.play-button { border-color: rgba(92, 232, 241, 0.45); color: var(--cyan-bright); }

.player-counter { margin-left: 4px; color: var(--quiet); font-family: var(--mono); font-size: 0.72rem; }

.player-speed { display: inline-flex; align-items: center; gap: 9px; margin-left: auto; color: var(--quiet); font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.08em; text-transform: uppercase; }

.speed-slider { width: 110px; accent-color: var(--cyan); }

/* labeled transport buttons: icon on top, tiny caption beneath */
.icon-button.labeled {
  width: auto;
  min-width: 52px;
  min-height: 46px;
  padding: 4px 10px;
  flex-direction: column;
  gap: 1px;
}

.icon-button.labeled .btn-ico { font-size: 0.95rem; line-height: 1.1; }

.icon-button.labeled .btn-lab {
  color: var(--quiet);
  font-family: var(--mono);
  font-size: 0.54rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.play-button.active { border-color: rgba(92, 232, 241, 0.7); background: rgba(24, 89, 103, 0.5); }
.play-button.active .btn-lab { color: var(--cyan-bright); }

/* the clear break between card controls and continuous-play controls */
.player-sep { width: 1px; height: 34px; margin: 0 6px; background: var(--line-strong); }

/* instant mode: settle all CSS stagger animations immediately */
.instant *, .instant *::before, .instant *::after {
  animation-delay: 0ms !important;
  animation-duration: 0.01ms !important;
}

.player-speed select {
  min-height: 34px;
  padding: 0 6px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--text);
  background: var(--surface);
  font-family: var(--mono);
  font-size: 0.78rem;
}

.player-scrub { width: 100%; accent-color: var(--cyan); }

/* ---------- lab visualization pieces ---------- */
.stage-note { margin: 0 0 12px; color: var(--quiet); font-size: 0.8rem; }

/* bit rows */
.bit-row { display: flex; align-items: center; gap: 10px; margin: 3px 0; }

.bit-label {
  flex: 0 0 92px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.7rem;
  text-align: right;
  white-space: nowrap;
}

.bit-cells { display: inline-flex; flex-wrap: wrap; gap: 6px; }

.bit-group { display: inline-flex; gap: 1px; }

.bit {
  display: inline-flex;
  width: 13px;
  height: 18px;
  align-items: center;
  justify-content: center;
  border-radius: 3px;
  font-family: var(--mono);
  font-size: 0.66rem;
  font-style: normal;
}

.bit.b0 { color: var(--quiet); background: rgba(9, 32, 43, 0.6); }
.bit.b1 { color: #001217; background: var(--cyan); font-weight: 700; }
.bit.bit-hot.b1 { background: var(--amber); }
.bit.bit-hot.b0 { background: rgba(245, 201, 106, 0.25); color: var(--amber); }
.bit-row.result .bit.b1 { background: var(--mint); }

.bit-op { margin: 2px 0 2px 102px; color: var(--quiet); font-family: var(--mono); font-size: 0.72rem; }

/* ---------- bit worksheets (aligned arithmetic-on-paper layout) ---------- */
.ws { margin: 16px 0 0; }

.ws-title { margin: 0 0 7px; color: var(--quiet); font-size: 0.78rem; line-height: 1.45; }
.ws-title b { font-weight: 650; }
.mark-amber { color: var(--amber); }
.mark-coral { color: var(--coral); }
.mark-cyan { color: var(--cyan-bright); }

.ws-section { margin: 20px 0 2px; color: var(--text); font-size: 0.88rem; font-weight: 700; letter-spacing: -0.01em; }

.ws-row { display: flex; align-items: center; gap: 8px; margin: 2px 0; width: max-content; }

.ws-label {
  flex: 0 0 128px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.68rem;
  text-align: right;
  white-space: nowrap;
}

.ws-op { flex: 0 0 14px; text-align: center; color: var(--amber); font-family: var(--mono); font-size: 0.74rem; }

/* highlighted bits: amber = wrapped around in a rotation, coral = fresh
   zeros from a shift, cyan = the bit a column chose / that agrees */
.bit.moved.b1 { background: var(--amber); color: #231600; }
.bit.moved.b0 { background: rgba(245, 201, 106, 0.3); color: var(--amber); }
.bit.zeroed.b0 { background: rgba(255, 123, 120, 0.25); color: var(--coral); }
.bit.zeroed.b1 { background: var(--coral); color: #230504; }
.bit.chosen.b1 { background: var(--cyan-bright); color: #001217; }
.bit.chosen.b0 { background: rgba(92, 232, 241, 0.3); color: var(--cyan-bright); }

/* ruled result row, like the answer line under a hand-worked sum;
   the answer sweeps in column by column, left to right */
.ws-row.result { margin-top: 5px; padding-top: 5px; border-top: 1px solid var(--line-strong); }
.ws-row.result .ws-label { color: var(--mint); }
.ws-row.result .bit.b1 { background: var(--mint); color: #01230f; }
.ws-row.result .bit {
  opacity: 0;
  animation: bit-in 180ms var(--ease-out) forwards;
  animation-delay: calc(var(--d, 0) * 55ms + 1.9s); /* after the crawls settle */
}

@keyframes bit-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

/* message char table */
.char-strip { display: flex; flex-wrap: wrap; gap: 8px; }

.char-tile {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  padding: 8px 9px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-3);
  font-family: var(--mono);
  animation: tile-in 300ms var(--ease-out);
}

.char-tile .c { font-size: 1.05rem; color: var(--text); font-weight: 700; }
.char-tile .b { font-size: 0.66rem; color: var(--amber); }
.char-tile .bits { font-size: 0.62rem; color: var(--cyan-bright); letter-spacing: 0.06em; }
.char-tile.current { border-color: rgba(92, 232, 241, 0.55); box-shadow: 0 0 0 1px rgba(92, 232, 241, 0.3); }

@keyframes tile-in { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: none; } }

/* padded bitstream */
.bitstream {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  line-height: 1.9;
  word-break: break-all;
  color: var(--quiet);
}

.bitstream .msg { color: var(--cyan-bright); }
.bitstream .one { color: #001217; background: var(--amber); border-radius: 3px; padding: 0 2px; font-weight: 700; }
.bitstream .len { color: var(--coral); }
.bitstream .zero { color: var(--quiet); opacity: 0.55; }

/* worked derivations (√prime → hex constant) and decimal check lines */
.derive {
  margin: 10px 0 14px;
  padding: 11px 14px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--amber);
  border-radius: 0 10px 10px 0;
  background: var(--surface-3);
  font-family: var(--mono);
  font-size: 0.76rem;
  line-height: 1.6;
}

.derive p { margin: 3px 0; color: var(--muted); }
.derive b { color: var(--cyan-bright); font-weight: 600; }

.derive .d-step {
  display: inline-flex;
  width: 17px;
  height: 17px;
  margin-right: 7px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  color: var(--amber);
  font-size: 0.6rem;
  font-weight: 700;
}

.ws-check {
  margin: 7px 0 2px 0;
  color: var(--quiet);
  font-family: var(--mono);
  font-size: 0.7rem;
  line-height: 1.5;
}

/* blocks bridge: cut → regroup → hex, colors carried the whole way */
.chunk-stream .block-chunk { display: inline; }
.chunk-stream .chunk-label { display: none; }

.chunk-stream.separated .block-chunk {
  display: block;
  margin: 10px 0;
  padding: 10px 12px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: var(--surface-3);
  animation: tile-in 420ms var(--ease-out);
}

.chunk-stream.separated .chunk-label {
  display: block;
  margin-bottom: 5px;
  color: var(--cyan-bright);
  font-size: 0.6rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.bword-list { margin: 8px 0; }

.bword-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 2px 0;
  font-family: var(--mono);
  opacity: 0;
  animation: tile-in 300ms var(--ease-out) forwards;
  animation-delay: calc(var(--d, 0) * 110ms);
}

.bword-row.shown { opacity: 1; animation: none; }

.bword-row .bw-label { flex: 0 0 34px; color: var(--quiet); font-size: 0.68rem; text-align: right; }
.bword-row .bw-bits { line-height: 1.5; white-space: nowrap; }
.bword-row .bw-arrow { color: var(--quiet); font-size: 0.75rem; }

.nibble { padding: 0 1px; }
.nibble.alt { background: rgba(132, 194, 214, 0.09); border-radius: 3px; }

.bw-hex .hexd {
  display: inline-block;
  min-width: 11px;
  color: var(--cyan-bright);
  font-size: 0.78rem;
  font-weight: 600;
  text-align: center;
  opacity: 0;
  animation: bit-in 160ms var(--ease-out) forwards;
  animation-delay: calc(var(--d, 0) * 22ms);
}

/* the schedule as a vertical list of binary rows, program-style */
.wlist { margin: 6px 0; font-family: var(--mono); }

.wlist-row {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 1px 0;
  white-space: nowrap;
}

.wlist-row .wl-label { flex: 0 0 34px; color: var(--quiet); font-size: 0.68rem; text-align: right; }
.wlist-row .wl-bits { color: var(--muted); font-size: 0.74rem; letter-spacing: 0.06em; }
.wlist-row .wl-ann { color: var(--amber); font-size: 0.7rem; }
.wlist-row.ref .wl-bits { color: var(--amber); }
.wlist-row.ref .wl-label { color: var(--amber); }
.wlist-row.new .wl-bits { color: var(--mint); }
.wlist-row.new .wl-label { color: var(--mint); }
.wlist-row.new .wl-ann { color: var(--mint); }

/* the row a function is currently operating on */
.wlist-row.op {
  margin: 0 -6px;
  padding: 1px 6px;
  border-radius: 6px;
  background: rgba(24, 89, 103, 0.35);
  outline: 1px solid rgba(92, 232, 241, 0.4);
}
.wlist-row.op .wl-ann { color: var(--cyan-bright); }

/* the new word landing in its slot */
.wlist-row.landed .wl-bits { animation: led-flash 900ms var(--ease-out); border-radius: 4px; }

/* word grids (message schedule, K constants) */
.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(96px, 1fr));
  gap: 5px;
  font-family: var(--mono);
  font-size: 0.72rem;
}

.word-cell {
  position: relative;
  padding: 5px 7px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface-3);
  color: var(--muted);
  text-align: center;
}

.word-cell .wi {
  display: block;
  margin-bottom: 1px;
  font-size: 0.56rem;
  color: var(--quiet);
  text-align: left;
  white-space: nowrap;
}
.word-cell.new { border-color: rgba(118, 230, 165, 0.6); color: var(--mint); animation: tile-in 300ms var(--ease-out); }
.word-cell.ref { border-color: rgba(245, 201, 106, 0.6); color: var(--amber); }
.word-cell.pending { opacity: 0.32; }

/* register table (a–h) */
.reg-table { display: flex; flex-direction: column; gap: 4px; font-family: var(--mono); }

.reg-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface-3);
  transition: border-color 240ms var(--ease-out), transform 240ms var(--ease-out), background 240ms var(--ease-out);
}

.reg-row .reg-name { width: 18px; color: var(--cyan-bright); font-weight: 700; font-size: 0.82rem; }
.reg-row .reg-val { color: var(--text); font-size: 0.82rem; letter-spacing: 0.05em; }
.reg-row .reg-src { margin-left: auto; color: var(--quiet); font-size: 0.62rem; }
.reg-row.empty { border-style: dashed; background: transparent; }
.reg-row.ellipsis { border-style: dashed; background: transparent; }
.reg-row.fill { opacity: 0; animation: tile-in 260ms var(--ease-out) forwards; animation-delay: calc(var(--d, 0) * 90ms); }
.wlist-row.fill { opacity: 0; animation: tile-in 260ms var(--ease-out) forwards; animation-delay: calc(var(--d, 0) * 90ms); }
.reg-row.ellipsis .reg-val { color: var(--quiet); font-size: 0.7rem; font-style: italic; }
.reg-row .reg-name.reg-wide { width: auto; min-width: 28px; }
.word-cell.fill { opacity: 0; animation: tile-in 260ms var(--ease-out) forwards; animation-delay: calc(var(--d, 0) * 32ms); }
.reg-row .reg-blank { color: var(--quiet); }
.reg-row .reg-val.bits { font-size: 0.62rem; letter-spacing: 0.04em; }

.morph-phase {
  margin: 0 0 10px;
  min-height: 1.4em;
  color: var(--amber);
  font-family: var(--mono);
  font-size: 0.76rem;
}

.reg-row.changed { border-color: rgba(118, 230, 165, 0.65); background: rgba(30, 84, 60, 0.25); }
.reg-row.changed .reg-val { color: var(--mint); }
.reg-row.shifted { border-color: rgba(245, 201, 106, 0.4); }

/* generic lab tables (trial division, egcd, encryption rows) */
.lab-table { border-collapse: collapse; width: 100%; font-family: var(--mono); font-size: 0.78rem; }

.lab-table th {
  padding: 5px 10px;
  border-bottom: 1px solid var(--line-strong);
  color: var(--quiet);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-align: left;
  text-transform: uppercase;
}

.lab-table td { padding: 4px 10px; border-bottom: 1px solid var(--line); color: var(--muted); }
.lab-table tr:last-child td { border-bottom: none; }
.lab-table tr.fresh td { animation: tile-in 280ms var(--ease-out); }
.lab-table td.ok { color: var(--mint); }
.lab-table td.bad { color: var(--coral); }
.lab-table tr.hit td { color: var(--text); background: rgba(24, 89, 103, 0.22); }

/* big formula line in viz */
.formula-line {
  margin: 4px 0 14px;
  font-family: var(--mono);
  font-size: clamp(0.9rem, 2.4vw, 1.15rem);
  color: var(--text);
  letter-spacing: 0.02em;
}

.formula-line .hl { color: var(--cyan-bright); }
.formula-line .hl2 { color: var(--amber); }

/* The map's growing cast: the row introduced by the current card flashes in */
.roadmap-cast .sym-row.cast-new .sym { color: var(--cyan-bright); }
.roadmap-cast .sym-row.cast-new { animation: cast-in 900ms var(--ease-out); }
@keyframes cast-in {
  from { background: rgba(41, 212, 227, 0.16); }
  to { background: transparent; }
}

/* The formula dock: after the map builds T₁/T₂, the equations stay pinned
   above the machine; the term(s) the current card works on light up. */
.formula-dock { display: none; padding: 10px 16px 4px; border-bottom: 1px dashed var(--line); }
.formula-dock.on { display: block; }
.formula-dock .f-line {
  margin: 0 0 7px;
  font-family: var(--mono);
  font-size: 0.86rem;
  letter-spacing: 0.02em;
  color: var(--quiet);
}
.formula-dock i { font-style: normal; }
.formula-dock [data-t] { transition: color 220ms var(--ease-out), text-shadow 220ms var(--ease-out); }
.formula-dock [data-t].hl {
  color: var(--cyan-bright);
  text-shadow: 0 0 14px rgba(41, 212, 227, 0.4);
}

/* key cards */
.key-cards { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 8px; }

.key-card {
  flex: 1 1 240px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-3);
  font-family: var(--mono);
}

.key-card.public { border-color: rgba(92, 232, 241, 0.45); }
.key-card.private { border-color: rgba(245, 201, 106, 0.45); }
.key-card h4 { margin: 0 0 7px; font-size: 0.68rem; letter-spacing: 0.13em; text-transform: uppercase; }
.key-card.public h4 { color: var(--cyan-bright); }
.key-card.private h4 { color: var(--amber); }
.key-card .kv { display: flex; gap: 10px; font-size: 0.85rem; color: var(--text); }
.key-card .kv b { width: 20px; color: var(--muted); font-weight: 600; }
.key-card p { margin: 8px 0 0; font-family: Inter, ui-sans-serif, sans-serif; font-size: 0.72rem; color: var(--quiet); }

/* digest strip */
.digest-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 10px 0;
  font-family: var(--mono);
}

.digest-strip span {
  padding: 6px 9px;
  border: 1px solid rgba(118, 230, 165, 0.5);
  border-radius: 8px;
  background: rgba(30, 84, 60, 0.22);
  color: var(--mint);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  animation: tile-in 320ms var(--ease-out);
}

.banner-ok {
  display: inline-block;
  margin-top: 10px;
  padding: 10px 16px;
  border: 1px solid rgba(118, 230, 165, 0.55);
  border-radius: var(--radius-sm);
  background: rgba(30, 84, 60, 0.25);
  color: var(--mint);
  font-family: var(--mono);
  font-size: 0.9rem;
  font-weight: 700;
}

.banner-ok.bad { border-color: rgba(255, 123, 120, 0.55); background: rgba(103, 40, 38, 0.25); color: var(--coral); }

/* security-chain diagram (RSA "why secure" step) */
.sec-chain { display: flex; flex-direction: column; gap: 7px; margin-top: 8px; font-family: var(--mono); font-size: 0.8rem; }
.sec-chain .link { display: flex; align-items: center; gap: 9px; padding: 7px 11px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface-3); color: var(--muted); }
.sec-chain .link b { color: var(--amber); font-weight: 700; }
.sec-chain .link.wall { border-color: rgba(255, 123, 120, 0.5); color: var(--coral); }

/* avalanche comparison */
.avalanche { margin-top: 16px; padding: 13px 15px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface-3); }
.avalanche h4 { margin: 0 0 8px; font-size: 0.86rem; }
.avalanche .stat { color: var(--amber); font-family: var(--mono); font-weight: 700; }

/* ---------- article ---------- */
.article {
  max-width: 780px;
  margin: 34px auto 0;
  padding: 0 clamp(16px, 3vw, 28px) 70px;
}

.article-rule {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 26px;
  color: var(--quiet);
  font-family: var(--mono);
  font-size: 0.66rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.article-rule::before, .article-rule::after { content: ""; flex: 1; height: 1px; background: var(--line); }

.article-section { margin: 0 0 34px; }

.article-section h2 {
  margin: 2px 0 12px;
  font-size: clamp(1.2rem, 2.6vw, 1.55rem);
  font-weight: 720;
  letter-spacing: -0.025em;
  line-height: 1.18;
}

.article-section h3 { margin: 0 0 6px; font-size: 0.98rem; font-weight: 700; }

.article-section p { margin: 0 0 12px; color: var(--muted); font-size: 0.92rem; }

.article-section a { color: var(--cyan-bright); text-decoration: none; border-bottom: 1px solid rgba(92, 232, 241, 0.35); }
.article-section a:hover { border-bottom-color: var(--cyan-bright); }

.article-section code {
  padding: 1px 5px;
  border-radius: 6px;
  background: rgba(9, 32, 43, 0.8);
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.84em;
}

.callout {
  margin: 16px 0;
  padding: 12px 14px;
  border-left: 3px solid var(--cyan);
  border-radius: 0 10px 10px 0;
  background: rgba(24, 89, 103, 0.14);
}

.callout.warn { border-left-color: var(--coral); background: rgba(103, 40, 38, 0.14); }
.callout.note { border-left-color: var(--violet); background: rgba(80, 60, 140, 0.14); }
.callout.key { border-left-color: var(--cyan); }
.callout p { margin: 0 0 8px; font-size: 0.86rem; }
.callout p:last-child { margin-bottom: 0; }
.callout h3 { margin: 0 0 7px; font-size: 0.86rem; letter-spacing: 0.01em; }

.formula {
  margin: 16px 0;
  padding: 13px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-2);
  text-align: center;
}

.formula code {
  display: block;
  padding: 0;
  background: none;
  color: var(--text);
  font-family: var(--mono);
  font-size: clamp(0.92rem, 2.4vw, 1.12rem);
  letter-spacing: 0.03em;
}

.formula figcaption { margin-top: 8px; color: var(--quiet); font-size: 0.78rem; }

.try { margin: 14px 0 4px; }

.try-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 15px;
  border: 1px solid rgba(92, 232, 241, 0.5) !important;
  border-radius: 10px;
  color: var(--cyan-bright) !important;
  background: rgba(24, 89, 103, 0.25);
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  text-decoration: none;
  transition: background 160ms var(--ease-out);
}

.try-link::before { content: "▶"; font-size: 0.62rem; }
.try-link:hover { background: rgba(24, 89, 103, 0.5); }

/* ---------- dialogs ---------- */
.site-dialog {
  width: min(92vw, 640px);
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  padding: 0;
  color: var(--text);
  background: var(--surface-2);
}

.site-dialog::backdrop { background: rgba(0, 5, 9, 0.76); backdrop-filter: blur(8px); }

.dialog-shell { position: relative; max-height: min(88vh, 760px); padding: 26px; overflow-y: auto; }

.dialog-kicker {
  margin: 0 0 6px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.dialog-shell h2 {
  max-width: 500px;
  margin: 0 48px 13px 0;
  font-size: clamp(1.2rem, 3vw, 1.6rem);
  font-weight: 720;
  letter-spacing: -0.026em;
  line-height: 1.15;
}

.dialog-shell p { margin: 0 0 11px; color: var(--muted); font-size: 0.88rem; line-height: 1.6; }

.creator-card {
  margin: 16px 0;
  padding: 13px 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-3);
}

.creator-card > span {
  display: block;
  margin-bottom: 4px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.58rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.creator-card strong { display: block; font-size: 0.94rem; }
.creator-card p { margin: 4px 0 0; font-size: 0.78rem; }
.creator-card a { color: var(--cyan-bright); text-decoration: none; }

.fine-print {
  margin: 14px 0 0;
  padding: 10px 12px;
  border-left: 3px solid var(--cyan);
  border-radius: 0 8px 8px 0;
  background: rgba(24, 89, 103, 0.14);
  color: var(--quiet);
  font-size: 0.72rem;
  line-height: 1.5;
}

.dialog-done {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  justify-content: center;
  margin-top: 14px;
  padding: 0 18px;
  border: 1px solid rgba(92, 232, 241, 0.5);
  border-radius: 10px;
  color: #001217;
  background: var(--cyan-bright);
  font: inherit;
  font-weight: 650;
  cursor: pointer;
}

.dialog-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 36px;
  height: 36px;
  border: 1px solid var(--line);
  border-radius: 9px;
  color: var(--muted);
  background: transparent;
  font-size: 1rem;
  cursor: pointer;
}

.dialog-close:hover { border-color: var(--line-strong); color: var(--text); }

/* ---------- section strip (algorithm picker under the topbar) ---------- */
.algo-strip {
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: 1240px;
  margin: 18px auto 0;
  padding: 0 clamp(16px, 3vw, 28px);
}

.algo-label {
  margin-right: 6px;
  color: var(--quiet);
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  white-space: nowrap;
}

.cross-link {
  margin-left: auto;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-decoration: none;
  white-space: nowrap;
}

.cross-link:hover { text-decoration: underline; }

@media (max-width: 640px) {
  .algo-strip { flex-wrap: wrap; }
  .cross-link { margin-left: 0; flex-basis: 100%; }
}

.view-tab {
  text-decoration: none;
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 8px;
  padding: 0 22px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  background: rgba(9, 32, 43, 0.55);
  font: inherit;
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  cursor: pointer;
  transition: border-color 160ms var(--ease-out), background 160ms var(--ease-out);
}

.view-tab:hover { border-color: var(--line-strong); color: var(--text); }

.view-tab.active {
  border-color: rgba(92, 232, 241, 0.6);
  color: var(--cyan-bright);
  background: rgba(24, 89, 103, 0.42);
}

.mode-note {
  max-width: 1240px;
  margin: 14px auto 0;
  padding: 0 clamp(16px, 3vw, 28px);
  color: var(--muted);
  font-size: 0.9rem;
}

/* the Learn pages' own-input bar: constrained and centered like page-head */
/* the input bar stows once the deck is running; ⏮ restart brings it back */
.lab-input.stowed { display: none; }

.lab-input.learn-bar {
  width: calc(100% - 2 * clamp(16px, 3vw, 28px));
  max-width: calc(1240px - 2 * clamp(16px, 3vw, 28px));
  margin: 14px auto 0;
}

/* ---------- clickable function demos ---------- */
/* any [data-fn] element opens the generic demo popup for that primitive */
[data-fn] { cursor: pointer; }
button.fn-link {
  padding: 0;
  border: none;
  background: none;
  font: inherit;
  text-align: left;
  color: inherit;
  text-decoration: underline dotted rgba(92, 232, 241, 0.6);
  text-underline-offset: 3px;
}
button.fn-link:hover { color: var(--cyan-bright); text-decoration-style: solid; }
.formula-dock [data-fn] { text-decoration: underline dotted rgba(92, 232, 241, 0.45); text-underline-offset: 3px; }
.formula-dock [data-fn]:hover { text-decoration-style: solid; }
.fn-hint { color: var(--quiet); font-size: 0.66rem; font-style: italic; }

.fn-dialog { width: min(94vw, 860px); }
.fn-dialog .fn-blurb { color: var(--muted); font-size: 0.9rem; }
.fn-dialog .fn-mount { margin: 14px 0; }
.fn-dialog .fn-replay { margin-top: 4px; }

/* Live values woven into the Learn prose — the sentences narrate the
   student's actual numbers, refilled (with a flash) when the input changes */
.live {
  font-family: var(--mono);
  font-size: 0.88em;
  color: var(--cyan-bright);
}
.live-hash { word-break: break-all; }
.live.live-flash { animation: live-flash 900ms var(--ease-out); }
@keyframes live-flash {
  from { background: rgba(41, 212, 227, 0.28); border-radius: 4px; }
  to { background: transparent; }
}

/* "Read the full story" link at the foot of each card's explanation */
.learn-more {
  margin: 14px 0 0;
  padding-top: 10px;
  border-top: 1px dashed var(--line);
}
.learn-more a {
  color: var(--cyan-bright);
  font-size: 0.78rem;
  text-decoration: none;
}
.learn-more a:hover { text-decoration: underline; }

/* Learn article pages: the head, the message bar, and the article all share
   ONE 780px column — no competing axes (same lesson as the lab landing). */
.learn-page .page-head { max-width: 780px; }
.learn-page .lab-input.learn-bar { max-width: calc(780px - 2 * clamp(16px, 3vw, 28px)); }

.play-button { border-color: rgba(92, 232, 241, 0.45); color: var(--cyan-bright); }

/* ---------- learn-mode demos ---------- */
/* An inline looping illustration, not a second lab: caption strip, the
   animation, one pause toggle — the article around it does the talking. */
.learn-demo {
  /* position: relative so the measuring probe lays out at the figure's own
     width — measured at any other width, the pinned height comes out wrong */
  position: relative;
  margin: 16px 0 6px;
  border: 1px solid var(--line);
  border-left: 3px solid rgba(41, 212, 227, 0.5);
  border-radius: var(--radius-md);
  background: var(--surface-2);
  overflow: hidden;
}

.learn-demo .ll-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin: 0;
  padding: 8px 15px;
  border-bottom: 1px solid var(--line);
  color: var(--amber);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.learn-demo .ll-head b { color: var(--cyan-bright); }
.learn-demo .ll-toggle {
  min-width: 30px;
  padding: 2px 8px;
  border: 1px solid var(--line);
  border-radius: 7px;
  color: var(--cyan-bright);
  background: transparent;
  cursor: pointer;
  font-size: 0.72rem;
}
.learn-demo .ll-toggle:hover { border-color: var(--line-strong); }

.learn-demo .learn-viz {
  /* height is pinned by JS to the tallest step of the loop, so the page
     never jiggles under the reader while the animation cycles */
  position: relative;
  padding: 13px 15px;
  overflow: auto;
}
.learn-demo .ll-probe {
  position: absolute;
  visibility: hidden;
  pointer-events: none;
  left: 0; right: 0;
  height: auto !important;
}

.learn-demo .learn-explain {
  padding: 0 15px 11px;
  color: var(--muted);
  font-size: 0.82rem;
}

.learn-demo .learn-explain h4 { margin: 0 0 6px; color: var(--text); font-size: 0.88rem; }
.learn-demo .learn-explain p { margin: 0 0 7px; }
.learn-demo .learn-explain .why {
  margin: 8px 0 0;
  padding: 8px 10px;
  border-left: 3px solid var(--cyan);
  border-radius: 0 8px 8px 0;
  background: rgba(24, 89, 103, 0.14);
  font-size: 0.78rem;
}
.learn-demo .learn-explain .why.warn { border-left-color: var(--coral); background: rgba(103, 40, 38, 0.16); }
.learn-demo .learn-explain .why.gold { border-left-color: var(--amber); background: rgba(103, 84, 34, 0.14); }
.learn-demo .learn-explain code {
  padding: 1px 5px;
  border-radius: 6px;
  background: rgba(9, 32, 43, 0.8);
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.8em;
}

.player-compact { padding: 9px 12px 12px; }
.player-compact .player-transport .icon-button { min-height: 34px; font-size: 0.8rem; }
.player-compact .player-counter { font-size: 0.66rem; }

/* ---------- responsive & a11y ---------- */
@media (max-width: 1080px) {
  .lab-grid { grid-template-columns: minmax(0, 1fr) minmax(270px, 330px); }
}

@media (max-width: 820px) {
  .lab-grid { grid-template-columns: 1fr; }
  .explain-panel { position: static; order: -1; }
  /* fixed heights in the stacked layout too, so the transport buttons below
     never move when the explanation or symbol list changes length */
  .explain-body { height: 220px; }
  .sym-body { height: 140px; }
  .brand h1 { font-size: 0.92rem; }
  .header-button span.hide-mobile { display: none; }
  .bit-label { flex-basis: 64px; font-size: 0.62rem; }
  .viz-body { min-height: 260px; }
}

@media (max-width: 480px) {
  .topbar { padding: 0 12px; }
  .header-button { padding: 0 9px; font-size: 0.74rem; }
  .bit { width: 11px; height: 16px; font-size: 0.58rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-delay: 0ms !important; transition-duration: 0.01ms !important; }
}

@media (prefers-contrast: more) {
  :root { --line: rgba(132, 194, 214, 0.4); --muted: #b8cdd6; --quiet: #93aebc; }
}

/* ===== Visualization vocabulary for the roadmap curriculum ===== */
.curriculum-strip{overflow-x:auto;flex-wrap:nowrap;scrollbar-width:thin}.curriculum-strip .view-tab{flex:0 0 auto}
.cast-list{display:grid;gap:8px;max-width:760px;margin:12px auto}.cast-row{display:grid;grid-template-columns:minmax(120px,.42fr) 1fr;gap:12px;align-items:center;padding:11px 14px;border:1px solid var(--line);border-radius:10px;background:rgba(8,26,37,.78)}.cast-row b{color:var(--cyan-bright);font-family:var(--mono)}.cast-row span{color:var(--muted);font-size:.82rem}.cast-row.cast-new{border-color:var(--amber);animation:tile-in 400ms var(--ease-out);box-shadow:0 0 24px rgba(245,201,106,.1)}
.lesson-equation{margin:18px auto 0;padding:14px 18px;max-width:850px;color:var(--text);border:1px solid var(--line-strong);border-radius:12px;background:rgba(41,212,227,.06);text-align:center;font:700 clamp(.75rem,2vw,1rem)/1.5 var(--mono)}.dock-stage{gap:14px!important;color:var(--muted)!important}.dock-stage b{color:var(--amber);text-transform:uppercase;letter-spacing:.08em}
.crypto-grid{display:grid;gap:6px;margin:14px auto;max-width:680px}.byte-grid,.word-grid{grid-template-columns:repeat(4,minmax(52px,1fr))}.crypto-cell{min-height:54px;display:grid;place-items:center;position:relative;padding:9px 5px;border:1px solid var(--line);border-radius:8px;background:var(--surface-soft);font-family:var(--mono);transition:transform .35s,border-color .35s,background .35s}.crypto-cell small{position:absolute;top:3px;left:5px;color:var(--quiet);font-size:.54rem}.crypto-cell b{color:var(--cyan-bright);font-size:.84rem}.word-grid .crypto-cell b{font-size:clamp(.58rem,1.4vw,.76rem)}.crypto-cell.active{border-color:var(--amber);background:rgba(245,201,106,.1);transform:translateY(-3px)}
.op-title{text-align:center;color:var(--amber);font:700 .8rem var(--mono);text-transform:uppercase;letter-spacing:.08em}.state-flow{display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:12px}.flow-arrow{color:var(--amber);font-size:2rem}.stage-note,.math-check{text-align:center;color:var(--muted);font:.75rem/1.55 var(--mono)}.math-check{padding:10px;border:1px dashed var(--line);border-radius:8px;overflow-wrap:anywhere}
.bit-calc{display:grid;gap:8px;max-width:720px;margin:20px auto}.bit-row{display:grid;grid-template-columns:1fr 150px;gap:12px;align-items:center}.bit-row>span{display:grid;grid-template-columns:repeat(8,1fr);gap:5px}.bit-row i{display:grid;place-items:center;height:42px;border:1px solid var(--line);border-radius:6px;color:var(--cyan-bright);background:var(--surface-soft);font:normal 700 .9rem var(--mono)}.bit-row b{color:var(--muted);font:600 .7rem var(--mono)}.bit-row.result{border-top:1px solid var(--line-strong);padding-top:8px}.bit-row.result i{color:var(--mint);border-color:rgba(118,230,165,.4)}
.byte-flight,.geometry-eq{display:flex;justify-content:center;align-items:stretch;gap:12px;margin:24px auto}.byte-flight>span,.geometry-eq>div{display:grid;place-items:center;min-width:105px;padding:14px;border:1px solid var(--line);border-radius:12px;background:var(--surface-soft);color:var(--cyan-bright);font:700 .92rem var(--mono)}.byte-flight>b,.geometry-eq>b{align-self:center;color:var(--text);font-size:1.2rem}.byte-flight small,.geometry-eq small{display:block;color:var(--quiet);font-size:.6rem;margin-top:6px}.byte-flight .secret,.hash-stack .secret{color:var(--amber);border-color:rgba(245,201,106,.35)}.byte-flight .result,.geometry-eq .result,.sbox-derive .result{color:var(--mint);border-color:rgba(118,230,165,.35)}
.reuse-attack{display:grid;gap:7px;max-width:880px;margin:18px auto;font-family:var(--mono)}.reuse-attack>div{display:grid;grid-template-columns:130px 1fr;padding:10px;border:1px solid var(--line);border-radius:8px;overflow-wrap:anywhere}.reuse-attack b{color:var(--cyan-bright)}.reuse-attack span{color:var(--muted)}.reuse-attack .danger{border-color:rgba(255,123,120,.5)}.reuse-attack .danger b{color:var(--coral)}.reuse-attack .reveal{border-color:rgba(118,230,165,.5)}.reuse-attack .reveal span{color:var(--mint)}
.rotor-machine{display:flex;justify-content:center;gap:clamp(10px,3vw,34px);margin:22px auto}.rotor{width:clamp(84px,15vw,130px);aspect-ratio:1;border:4px double var(--line-strong);border-radius:50%;display:grid;place-items:center;background:radial-gradient(circle,var(--surface-soft),var(--surface));box-shadow:inset 0 0 22px rgba(41,212,227,.08)}.rotor small,.rotor span{display:block;color:var(--quiet);font:.6rem var(--mono)}.rotor b{color:var(--amber);font:800 1.7rem var(--mono)}.rotor.turn{animation:rotor-turn 800ms var(--ease-out);border-color:var(--amber)}@keyframes rotor-turn{from{transform:rotate(-28deg)}to{transform:rotate(0)}}
.signal-path{display:flex;gap:8px;overflow-x:auto;padding:18px 4px}.signal-path>div{flex:0 0 86px;min-height:74px;display:grid;place-items:center;border:1px solid var(--line);border-radius:10px;background:var(--surface-soft);animation:signal-on 500ms calc(var(--i)*120ms) both}.signal-path small{color:var(--quiet);font:.56rem var(--mono);text-align:center}.signal-path b{color:var(--cyan-bright);font:800 1.1rem var(--mono)}@keyframes signal-on{from{opacity:.2;transform:translateX(-8px);border-color:var(--line)}to{opacity:1;transform:none;border-color:var(--cyan)}}
.alphabet-map{display:grid;grid-template-columns:repeat(13,1fr);gap:5px}.alphabet-map span{display:grid;place-items:center;padding:5px 2px;border:1px solid var(--line);border-radius:5px;font:.62rem var(--mono)}.alphabet-map b{color:var(--cyan-bright)}.alphabet-map i{color:var(--quiet)}.alphabet-map em{color:var(--amber);font-style:normal}
.sbox-derive,.hash-stack{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:10px;margin:22px auto}.sbox-derive>div,.hash-stack>div{padding:14px;border:1px solid var(--line);border-radius:10px;background:var(--surface-soft);font-family:var(--mono);overflow-wrap:anywhere}.sbox-derive small{display:block;color:var(--quiet)}.sbox-derive b{color:var(--cyan-bright);font-size:1.25rem}.sbox-derive i,.hash-stack i{color:var(--muted);font:normal .7rem var(--mono)}
.round-meter{display:grid;grid-template-columns:repeat(10,1fr);gap:4px;margin:10px 0}.round-meter i{padding:7px 2px;text-align:center;border:1px solid var(--line);border-radius:5px;color:var(--quiet);font:normal .55rem var(--mono)}.round-meter i.done{color:var(--mint);border-color:rgba(118,230,165,.35);background:rgba(118,230,165,.07)}
.power-card{display:grid;gap:12px;max-width:760px;margin:24px auto;padding:20px;border:1px solid var(--line-strong);border-radius:14px;background:var(--surface-soft);text-align:center}.power-card strong{color:var(--amber)}.power-card code{color:var(--cyan-bright);font:700 clamp(.9rem,3vw,1.35rem) var(--mono)}.power-card span{color:var(--muted);font-size:.78rem}
.party-flow{display:grid;grid-template-columns:1fr 1.3fr 1fr;align-items:center;gap:12px;margin:22px auto;max-width:800px}.party,.channel{padding:18px;border:1px solid var(--line);border-radius:12px;text-align:center;background:var(--surface-soft)}.party b{display:block;color:var(--amber)}.party span,.channel span{display:block;color:var(--cyan-bright);font-family:var(--mono)}.channel i{display:block;color:var(--quiet);font-size:.68rem}.converge{display:flex;justify-content:center;align-items:center;gap:18px;margin:26px auto}.converge>div{padding:18px;border:1px solid rgba(118,230,165,.35);border-radius:12px;color:var(--muted)}.converge b{display:block;color:var(--mint);font-family:var(--mono)}.converge i{color:var(--mint);font-size:1.5rem}
.log-table{display:grid;grid-template-columns:repeat(11,1fr);gap:4px}.log-table span{display:grid;place-items:center;padding:6px 2px;border:1px solid var(--line);border-radius:5px;color:var(--muted);font:.6rem var(--mono)}.log-table small{color:var(--quiet)}.log-table .hit{border-color:var(--coral);color:var(--coral);background:rgba(255,123,120,.08)}
.curve-wrap{max-width:760px;margin:10px auto;text-align:center}.curve-wrap svg{width:100%;border:1px solid var(--line);border-radius:12px;background:radial-gradient(circle,rgba(41,212,227,.07),transparent)}.curve-wrap path{stroke:var(--line-strong);fill:none}.curve-wrap circle{fill:var(--cyan);opacity:.55}.curve-wrap circle.base{fill:var(--amber);opacity:1}.curve-wrap p{color:var(--muted);font:.72rem var(--mono)}
.tamper-card{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:center;margin:22px auto}.tamper-card>div{padding:16px;border:1px solid var(--line);border-radius:10px;overflow-wrap:anywhere}.tamper-card small{display:block;color:var(--quiet)}.tamper-card b{color:var(--cyan-bright);font:.7rem var(--mono)}.tamper-card .danger{border-color:var(--coral)}.tamper-card .danger b{color:var(--coral)}.tamper-card i{color:var(--coral)}.tamper-card p{grid-column:1/-1;text-align:center;color:var(--coral)}
.hello-card,.certificate-card{max-width:620px;margin:20px auto;padding:20px;border:1px solid var(--line-strong);border-radius:14px;background:var(--surface-soft)}.hello-card b,.certificate-card h4{color:var(--cyan-bright)}.hello-card code{display:block;color:var(--amber);margin:8px 0}.hello-card li{color:var(--muted)}.certificate-card small{color:var(--quiet);text-transform:uppercase;letter-spacing:.1em}.certificate-card p{color:var(--muted);font-family:var(--mono)}.certificate-card>b{color:var(--mint)}
.tls-timeline{display:grid;grid-template-columns:repeat(7,1fr);gap:4px;margin-top:20px}.tls-timeline span{display:grid;place-items:center;padding:7px;border:1px solid var(--line);border-radius:6px;color:var(--quiet);font:.62rem var(--mono)}.tls-timeline small{font-size:.48rem}.tls-timeline .done{color:var(--mint);border-color:rgba(118,230,165,.35)}
@media(max-width:700px){.state-flow{grid-template-columns:1fr}.flow-arrow{transform:rotate(90deg);text-align:center}.bit-row{grid-template-columns:1fr}.byte-flight,.geometry-eq{gap:5px}.byte-flight>span,.geometry-eq>div{min-width:70px;padding:9px}.party-flow{grid-template-columns:1fr}.alphabet-map{grid-template-columns:repeat(7,1fr)}.log-table{grid-template-columns:repeat(6,1fr)}.tamper-card{grid-template-columns:1fr}.tamper-card i{text-align:center}.tls-timeline{grid-template-columns:repeat(4,1fr)}}
@media(prefers-reduced-motion:reduce){.rotor.turn,.signal-path>div{animation:none!important}}