/* ============================================================
   Signal Path — site design system
   Palette: radio-night blue-blacks + Flipper orange + waterfall cyan
   Type:    Archivo (display) · Public Sans (body) · IBM Plex Mono (data)
   ============================================================ */

:root {
  /* light — lab worksheet on cool paper */
  --bg: #EFF1ED;
  --surface: #FFFFFF;
  --surface-2: #F6F7F3;
  --surface-3: #E9EBE5;
  --line: #DCDFD8;
  --line-strong: #C7CBC1;
  --text: #191E24;
  --muted: #565F6B;
  --faint: #6E7682;
  --orange: #D9540A;
  --orange-ink: #B84406;
  --orange-soft: rgba(217, 84, 10, 0.10);
  --btn-primary-bg: #B84406;   /* white text ≈ 6:1 (AA) */
  --btn-primary-ink: #FFFFFF;
  --cyan: #0C8F8A;
  --cyan-soft: rgba(12, 143, 138, 0.10);
  --red: #C7364F;
  --red-soft: rgba(199, 54, 79, 0.09);
  --green: #23875A;
  --green-soft: rgba(35, 135, 90, 0.10);
  --yellow: #B4801A;
  --yellow-soft: rgba(180, 128, 26, 0.12);
  --purple: #6B4FBB;
  --purple-soft: rgba(107, 79, 187, 0.10);
  --shadow: 0 1px 2px rgba(20, 25, 33, 0.05), 0 8px 24px rgba(20, 25, 33, 0.06);
  --shadow-lift: 0 2px 6px rgba(20, 25, 33, 0.08), 0 16px 40px rgba(20, 25, 33, 0.10);
  --lcd-bg: #F6A03A;         /* flipper-style LCD backlight */
  --lcd-ink: #1B1509;
  --scope-bg: #0B1220;       /* instrument screens stay dark in both themes */
  --scope-grid: #1B2A44;
  --scope-trace: #3FD8D2;
  --scope-peak: #FF8A34;
  --scope-text: #9BB3D1;
  --radius: 14px;
  --radius-sm: 9px;
  --font-display: "Archivo", ui-sans-serif, system-ui, sans-serif;
  --font-body: "Public Sans", ui-sans-serif, system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
  color-scheme: light;
}

:root:not([data-theme="light"]) {
  @media (prefers-color-scheme: dark) {
    --bg: #0D1119;
    --surface: #141A25;
    --surface-2: #1B2331;
    --surface-3: #232D3D;
    --line: #29323F;
    --line-strong: #3A4657;
    --text: #E8EDF4;
    --muted: #9BA8B9;
    --faint: #8794A6;
    --orange: #FF8A34;
    --orange-ink: #FFA45C;
    --orange-soft: rgba(255, 138, 52, 0.13);
    --btn-primary-bg: #FF8A34;   /* dark ink on this ≈ 8:1 (AA) */
    --btn-primary-ink: #1B1509;
    --cyan: #3FD8D2;
    --cyan-soft: rgba(63, 216, 210, 0.12);
    --red: #FF6A86;
    --red-soft: rgba(255, 106, 134, 0.11);
    --green: #55D08D;
    --green-soft: rgba(85, 208, 141, 0.12);
    --yellow: #F0C25A;
    --yellow-soft: rgba(240, 194, 90, 0.13);
    --purple: #A48CF0;
    --purple-soft: rgba(164, 140, 240, 0.13);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 10px 30px rgba(0, 0, 0, 0.35);
    --shadow-lift: 0 2px 8px rgba(0, 0, 0, 0.45), 0 20px 50px rgba(0, 0, 0, 0.5);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #0D1119;
  --surface: #141A25;
  --surface-2: #1B2331;
  --surface-3: #232D3D;
  --line: #29323F;
  --line-strong: #3A4657;
  --text: #E8EDF4;
  --muted: #9BA8B9;
  --faint: #8794A6;
  --orange: #FF8A34;
  --orange-ink: #FFA45C;
  --orange-soft: rgba(255, 138, 52, 0.13);
  --btn-primary-bg: #FF8A34;   /* dark ink on this ≈ 8:1 (AA) */
  --btn-primary-ink: #1B1509;
  --cyan: #3FD8D2;
  --cyan-soft: rgba(63, 216, 210, 0.12);
  --red: #FF6A86;
  --red-soft: rgba(255, 106, 134, 0.11);
  --green: #55D08D;
  --green-soft: rgba(85, 208, 141, 0.12);
  --yellow: #F0C25A;
  --yellow-soft: rgba(240, 194, 90, 0.13);
  --purple: #A48CF0;
  --purple-soft: rgba(164, 140, 240, 0.13);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 10px 30px rgba(0, 0, 0, 0.35);
  --shadow-lift: 0 2px 8px rgba(0, 0, 0, 0.45), 0 20px 50px rgba(0, 0, 0, 0.5);
  color-scheme: dark;
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, h4 {
  font-family: var(--font-display);
  text-wrap: balance;
  letter-spacing: -0.01em;
  line-height: 1.12;
  margin: 0;
}
h1 { font-size: clamp(34px, 6vw, 56px); font-weight: 800; }
h2 { font-size: clamp(24px, 4vw, 32px); font-weight: 700; }
h3 { font-size: 20px; font-weight: 700; }
h4 { font-size: 16px; font-weight: 700; }
p { margin: 0 0 1em; max-width: 68ch; }
ul, ol { margin: 0 0 1em; padding-left: 22px; max-width: 68ch; }
li { margin-bottom: 6px; }
li > ul, li > ol { margin-top: 6px; margin-bottom: 0; }
strong, b { font-weight: 600; color: var(--text); }
a { color: var(--orange-ink); text-decoration-color: color-mix(in srgb, var(--orange-ink) 40%, transparent); text-underline-offset: 2px; }
a:hover { text-decoration-color: var(--orange-ink); }
:focus-visible { outline: 2px solid var(--orange); outline-offset: 2px; border-radius: 3px; }
img, svg, canvas, video { max-width: 100%; height: auto; }
hr { border: 0; border-top: 1px solid var(--line); margin: 32px 0; }
code, kbd, samp, .mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}
code { font-size: 0.9em; background: var(--surface-3); padding: 1px 6px; border-radius: 5px; color: var(--text); }
pre {
  background: var(--surface-3); border: 1px solid var(--line); border-radius: var(--radius-sm);
  padding: 14px 16px; overflow-x: auto; font-size: 13px; line-height: 1.55; margin: 0 0 1.2em;
}
pre code { background: none; padding: 0; font-size: inherit; }
kbd {
  display: inline-block; font-size: 12px; font-weight: 600; padding: 1px 7px 2px;
  border: 1px solid var(--line-strong); border-bottom-width: 2px; border-radius: 6px;
  background: var(--surface); color: var(--text); line-height: 1.4;
}
table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table-scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius-sm); box-shadow: var(--shadow); margin: 0 0 1.4em; background: var(--surface); }
.table-scroll table { min-width: 520px; }
thead th {
  text-align: left; font-family: var(--font-mono); font-size: 11px; text-transform: uppercase;
  letter-spacing: 0.08em; color: var(--faint); font-weight: 600; padding: 12px 14px;
  background: var(--surface-2); border-bottom: 1px solid var(--line);
}
tbody td { padding: 11px 14px; border-bottom: 1px solid var(--line); color: var(--muted); vertical-align: top; }
tbody tr:last-child td { border-bottom: none; }
tbody tr:nth-child(odd) td { background: color-mix(in srgb, var(--surface-2) 45%, transparent); }
td .mono, th .mono, td code { color: var(--text); }
td b { color: var(--text); }

.eyebrow {
  font-family: var(--font-mono); text-transform: uppercase; letter-spacing: 0.18em;
  font-size: 11.5px; font-weight: 600; color: var(--faint); margin: 0 0 8px;
}
.muted { color: var(--muted); }
.faint { color: var(--faint); }
.lede { font-size: clamp(17px, 2.2vw, 20px); color: var(--muted); max-width: 62ch; }
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 22px; }
.wrap-narrow { max-width: 820px; margin: 0 auto; padding: 0 22px; }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- pills / badges / chips ---------- */
.pill { display: inline-block; font-family: var(--font-mono); font-size: 11px; padding: 2px 8px; border-radius: 6px; font-weight: 600; line-height: 1.6; white-space: nowrap; }
.pill.am, .pill.orange { background: var(--orange-soft); color: var(--orange); }
.pill.fm, .pill.cyan { background: var(--cyan-soft); color: var(--cyan); }
.pill.fixed, .pill.green { background: var(--green-soft); color: var(--green); }
.pill.rolling, .pill.red { background: var(--red-soft); color: var(--red); }
.pill.yellow { background: var(--yellow-soft); color: var(--yellow); }
.pill.purple { background: var(--purple-soft); color: var(--purple); }
.pill.grey { background: var(--surface-3); color: var(--muted); }
.chips { display: flex; flex-wrap: wrap; gap: 9px; }
.chip {
  display: inline-flex; align-items: center; gap: 7px; font-family: var(--font-mono); font-size: 12.5px; font-weight: 500;
  background: var(--surface); border: 1px solid var(--line); border-radius: 999px; padding: 6px 12px; color: var(--muted);
}
.chip b { color: var(--text); font-weight: 600; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-family: var(--font-body); font-weight: 600; font-size: 14px; line-height: 1.2;
  padding: 10px 16px; border-radius: 10px; border: 1px solid var(--line-strong);
  background: var(--surface); color: var(--text); cursor: pointer; text-decoration: none;
  transition: transform 0.12s ease, box-shadow 0.12s ease, background 0.12s ease, border-color 0.12s ease;
}
.btn:hover { border-color: var(--faint); box-shadow: var(--shadow); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn.primary { background: var(--btn-primary-bg); border-color: var(--btn-primary-bg); color: var(--btn-primary-ink); }
.btn.primary:hover { filter: brightness(0.93); }
.btn.ghost { background: transparent; border-color: transparent; color: var(--muted); }
.btn.ghost:hover { background: var(--surface-2); color: var(--text); box-shadow: none; transform: none; }
.btn.small { font-size: 12.5px; padding: 6px 11px; border-radius: 8px; }
.btn.mono { font-family: var(--font-mono); font-size: 12px; }
.btn[disabled], .btn[aria-disabled="true"] { opacity: 0.5; cursor: not-allowed; transform: none; box-shadow: none; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  background: color-mix(in srgb, var(--bg) 84%, transparent);
  border-bottom: 1px solid var(--line);
}
.topbar-inner { display: flex; align-items: center; gap: 14px; padding: 10px 22px; max-width: 1080px; margin: 0 auto; }
.brand { display: flex; align-items: center; gap: 9px; font-family: var(--font-display); font-weight: 800; letter-spacing: -0.02em; font-size: 15px; color: var(--text); text-decoration: none; }
.brand .dot { width: 10px; height: 10px; border-radius: 50%; background: var(--orange); box-shadow: 0 0 0 3px var(--orange-soft); }
.topnav { display: flex; gap: 2px; margin-left: auto; flex-wrap: wrap; }
.topnav a { font-size: 13px; color: var(--muted); text-decoration: none; padding: 5px 9px; border-radius: 7px; white-space: nowrap; }
.topnav a:hover { color: var(--text); background: var(--surface-2); }
.topnav a[aria-current="page"] { color: var(--orange); background: var(--orange-soft); }
.theme-btn, .icon-btn {
  font-family: var(--font-mono); font-size: 12px; font-weight: 600;
  background: var(--surface); color: var(--muted);
  border: 1px solid var(--line); border-radius: 8px; padding: 6px 10px; cursor: pointer; line-height: 1.3;
}
.theme-btn:hover, .icon-btn:hover { color: var(--text); border-color: var(--line-strong); }
.nav-progress { display: none; align-items: center; gap: 8px; font-family: var(--font-mono); font-size: 11.5px; color: var(--faint); }
.nav-progress .mini-bar { width: 70px; height: 6px; background: var(--line); border-radius: 999px; overflow: hidden; }
.nav-progress .mini-bar i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--orange), var(--yellow)); }
@media (min-width: 900px) { .nav-progress { display: inline-flex; } }
.nav-toggle { display: none; }
@media (max-width: 760px) {
  .topnav { display: none; position: absolute; left: 0; right: 0; top: 100%; flex-direction: column; background: var(--surface); border-bottom: 1px solid var(--line); padding: 8px 12px 12px; box-shadow: var(--shadow-lift); }
  .topnav.open { display: flex; }
  .topnav a { padding: 10px 10px; font-size: 15px; }
  .nav-toggle { display: inline-flex; margin-left: auto; }
  .topbar-inner { position: relative; }
  .topbar .theme-btn { margin-left: 0; }
}

/* ---------- layout: page with sidebar TOC ---------- */
.page { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 44px; max-width: 1080px; margin: 0 auto; padding: 36px 22px 80px; }
@media (max-width: 900px) { .page { grid-template-columns: minmax(0, 1fr); gap: 20px; padding-top: 24px; } }
.toc { position: sticky; top: 72px; align-self: start; font-size: 13px; }
@media (max-width: 900px) { .toc { position: static; border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 12px 14px; background: var(--surface); } }
.toc .eyebrow { margin-bottom: 10px; }
.toc ol { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 2px; }
.toc a { display: block; color: var(--muted); text-decoration: none; padding: 5px 10px; border-left: 2px solid var(--line); border-radius: 0 6px 6px 0; }
.toc a:hover { color: var(--text); background: var(--surface-2); }
.toc a.active { color: var(--orange); border-left-color: var(--orange); background: var(--orange-soft); }
.toc .toc-next { margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--line); display: flex; flex-direction: column; gap: 8px; }
.content { min-width: 0; }
.content > section { scroll-margin-top: 76px; padding: 8px 0 24px; }
.content > section + section { border-top: 1px solid var(--line); padding-top: 30px; }
.content h2 { margin-bottom: 14px; }
.content h3 { margin: 26px 0 10px; }
.content h4 { margin: 20px 0 8px; }

/* module header */
.mod-header { display: flex; align-items: flex-start; gap: 18px; margin-bottom: 26px; }
.mod-index {
  flex-shrink: 0; width: 60px; height: 60px; border-radius: 14px;
  background: var(--orange-soft); color: var(--orange);
  display: grid; place-items: center; font-family: var(--font-display); font-weight: 800; font-size: 26px;
  border: 1px solid color-mix(in srgb, var(--orange) 30%, transparent);
}
.mod-titles { flex: 1; min-width: 0; }
.mod-week { font-family: var(--font-mono); font-size: 11.5px; color: var(--faint); text-transform: uppercase; letter-spacing: 0.12em; }
.mod-titles h1 { font-size: clamp(28px, 4.5vw, 40px); margin-top: 4px; }
.mod-titles .lede { margin-top: 10px; font-size: 16.5px; }
.mod-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }

/* ---------- cards & callouts ---------- */
.card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px 22px; box-shadow: var(--shadow);
}
.card.flat { box-shadow: none; }
.card.tight { padding: 14px 16px; }
.grid2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; margin: 0 0 1.4em; }
.grid3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin: 0 0 1.4em; }
@media (max-width: 760px) { .grid2, .grid3 { grid-template-columns: minmax(0, 1fr); } }
@media (min-width: 761px) and (max-width: 980px) { .grid3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }

.callout {
  display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 12px; align-items: start;
  border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 14px 16px; margin: 0 0 1.4em;
  background: var(--surface-2); font-size: 14.5px;
}
.callout > .ic { font-family: var(--font-mono); font-weight: 700; font-size: 13px; line-height: 1.6; padding: 0 6px; border-radius: 5px; }
.callout p:last-child, .callout ul:last-child, .callout ol:last-child { margin-bottom: 0; }
.callout .callout-title { font-weight: 700; color: var(--text); display: block; margin-bottom: 4px; font-family: var(--font-display); }
.callout.note { background: var(--cyan-soft); border-color: color-mix(in srgb, var(--cyan) 35%, transparent); }
.callout.note > .ic { color: var(--cyan); background: color-mix(in srgb, var(--cyan) 15%, transparent); }
.callout.tip { background: var(--green-soft); border-color: color-mix(in srgb, var(--green) 35%, transparent); }
.callout.tip > .ic { color: var(--green); background: color-mix(in srgb, var(--green) 15%, transparent); }
.callout.warn { background: var(--yellow-soft); border-color: color-mix(in srgb, var(--yellow) 40%, transparent); }
.callout.warn > .ic { color: var(--yellow); background: color-mix(in srgb, var(--yellow) 18%, transparent); }
.callout.legal { background: var(--red-soft); border-color: color-mix(in srgb, var(--red) 40%, transparent); }
.callout.legal > .ic { color: var(--red); background: color-mix(in srgb, var(--red) 15%, transparent); }
.callout.story { background: var(--purple-soft); border-color: color-mix(in srgb, var(--purple) 35%, transparent); }
.callout.story > .ic { color: var(--purple); background: color-mix(in srgb, var(--purple) 15%, transparent); }

/* lab block */
.lab {
  background: var(--surface); border: 1px solid var(--line); border-left: 4px solid var(--orange);
  border-radius: var(--radius-sm); padding: 18px 20px; margin: 0 0 1.4em; box-shadow: var(--shadow);
}
.lab .lab-kicker { font-family: var(--font-mono); font-size: 11.5px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--orange); margin-bottom: 4px; }
.lab h3 { margin: 0 0 10px; font-size: 18px; }
.lab ol { margin: 0; }
.lab ol li { margin-bottom: 8px; }
.lab .lab-gear { font-size: 13px; color: var(--muted); margin: 0 0 12px; }
.lab .lab-gear b { color: var(--text); }
.lab .flip { color: var(--orange-ink); background: var(--orange-soft); padding: 1px 6px; border-radius: 4px; font-family: var(--font-mono); font-size: 0.9em; white-space: nowrap; }

/* "you've got it when" */
.win {
  display: flex; align-items: flex-start; gap: 10px;
  font-size: 14px; color: var(--muted); background: var(--green-soft);
  border: 1px solid color-mix(in srgb, var(--green) 30%, transparent);
  border-radius: var(--radius-sm); padding: 12px 14px; margin: 0 0 1.4em;
}
.win .ic { color: var(--green); font-family: var(--font-mono); font-weight: 700; flex-shrink: 0; }
.win b { color: var(--text); }

/* key facts strip */
.facts { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; margin: 0 0 1.4em; }
.fact { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 12px 14px; }
.fact .v { font-family: var(--font-mono); font-size: 20px; font-weight: 600; color: var(--orange); letter-spacing: -0.01em; }
.fact .k { font-size: 12px; color: var(--faint); margin-top: 2px; }

/* steps (numbered process) */
.steps { list-style: none; padding: 0; margin: 0 0 1.4em; counter-reset: step; max-width: none; }
.steps > li { counter-increment: step; display: grid; grid-template-columns: 34px minmax(0, 1fr); gap: 12px; margin-bottom: 12px; }
.steps > li::before {
  content: counter(step); width: 30px; height: 30px; border-radius: 50%;
  background: var(--orange-soft); color: var(--orange); font-family: var(--font-mono); font-weight: 600; font-size: 13px;
  display: grid; place-items: center; border: 1px solid color-mix(in srgb, var(--orange) 30%, transparent);
}

/* key-value definition list */
.kv { display: grid; grid-template-columns: max-content minmax(0, 1fr); gap: 6px 18px; margin: 0 0 1.4em; font-size: 14px; }
.kv dt { font-family: var(--font-mono); color: var(--faint); font-size: 12.5px; padding-top: 2px; }
.kv dd { margin: 0; color: var(--muted); }
.kv dd b { color: var(--text); }

/* flipper-ish menu path */
.flip { color: var(--orange-ink); background: var(--orange-soft); padding: 1px 6px; border-radius: 4px; font-family: var(--font-mono); font-size: 0.9em; white-space: nowrap; }

/* details */
details { border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--surface); margin: 0 0 12px; }
details > summary { cursor: pointer; padding: 12px 16px; font-weight: 600; list-style: none; display: flex; align-items: center; gap: 10px; }
details > summary::-webkit-details-marker { display: none; }
details > summary::before { content: "▸"; color: var(--orange); font-family: var(--font-mono); transition: transform 0.15s; }
details[open] > summary::before { transform: rotate(90deg); }
details > .d-body { padding: 0 16px 14px; font-size: 14.5px; color: var(--muted); }
details > .d-body p:last-child { margin-bottom: 0; }

/* figure */
figure { margin: 0 0 1.4em; }
figure.diagram { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 16px; overflow-x: auto; }
figcaption { font-size: 12.5px; color: var(--faint); margin-top: 8px; font-family: var(--font-mono); }

/* ---------- widget shell ---------- */
.widget {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); margin: 0 0 1.6em; overflow: hidden;
}
.widget-head {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 12px 16px; border-bottom: 1px solid var(--line); background: var(--surface-2);
}
.widget-head .widget-title { font-family: var(--font-display); font-weight: 700; font-size: 14.5px; display: flex; align-items: center; gap: 8px; }
.widget-head .widget-title .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 0 3px var(--cyan-soft); }
.widget-head .widget-sub { font-size: 12.5px; color: var(--faint); }
.widget-head .spacer { flex: 1; }
.widget-body { padding: 16px; }
.widget-foot { padding: 10px 16px; border-top: 1px solid var(--line); font-size: 12.5px; color: var(--faint); }
.widget-controls { display: flex; flex-wrap: wrap; gap: 10px 16px; align-items: center; margin-bottom: 12px; }
.widget-controls label { display: inline-flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); font-family: var(--font-mono); }
.widget-controls input[type="range"] { accent-color: var(--orange); width: 150px; }
.widget-controls select, .widget-controls input[type="text"], .widget-controls input[type="number"] {
  font-family: var(--font-mono); font-size: 13px; padding: 5px 8px; border-radius: 7px;
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--text);
}
.widget .readout { font-family: var(--font-mono); font-size: 13px; color: var(--muted); }
.widget .readout b { color: var(--orange); font-weight: 600; }
.seg { display: inline-flex; border: 1px solid var(--line-strong); border-radius: 8px; overflow: hidden; }
.seg button {
  font-family: var(--font-mono); font-size: 12.5px; font-weight: 600; padding: 6px 12px; border: 0;
  background: var(--surface); color: var(--muted); cursor: pointer;
}
.seg button + button { border-left: 1px solid var(--line-strong); }
.seg button[aria-pressed="true"] { background: var(--btn-primary-bg); color: var(--btn-primary-ink); }
.scope { display: block; width: 100%; background: var(--scope-bg); border-radius: 8px; border: 1px solid var(--scope-grid); }

/* Flipper-style LCD */
.lcd {
  background: var(--lcd-bg); color: var(--lcd-ink); border-radius: 6px; padding: 8px;
  font-family: var(--font-mono); font-size: 12px; line-height: 1.35; letter-spacing: 0.02em;
  box-shadow: inset 0 0 0 2px rgba(0,0,0,0.25), inset 0 0 18px rgba(0,0,0,0.15);
  image-rendering: pixelated;
}

/* ---------- quiz ---------- */
.quiz { margin: 0 0 1.6em; }
.quiz .q { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 16px 18px; margin-bottom: 12px; }
.quiz .q-num { font-family: var(--font-mono); font-size: 11.5px; color: var(--faint); text-transform: uppercase; letter-spacing: 0.1em; }
.quiz .q-text { font-weight: 600; margin: 4px 0 12px; font-size: 15.5px; }
.quiz .opts { display: flex; flex-direction: column; gap: 8px; }
.quiz .opt {
  display: flex; align-items: flex-start; gap: 10px; text-align: left; width: 100%;
  font-family: var(--font-body); font-size: 14px; color: var(--text);
  background: var(--surface-2); border: 1px solid var(--line); border-radius: 9px; padding: 10px 12px; cursor: pointer;
}
.quiz .opt:hover { border-color: var(--line-strong); }
.quiz .opt .letter { font-family: var(--font-mono); font-weight: 600; font-size: 12px; color: var(--faint); width: 18px; flex-shrink: 0; padding-top: 1px; }
.quiz .opt.correct { background: var(--green-soft); border-color: var(--green); }
.quiz .opt.wrong { background: var(--red-soft); border-color: var(--red); }
.quiz .opt[disabled] { cursor: default; }
.quiz .explain { margin-top: 12px; font-size: 13.5px; color: var(--muted); padding: 10px 12px; background: var(--surface-2); border-radius: 8px; border-left: 3px solid var(--cyan); }
.quiz .explain.ok { border-left-color: var(--green); }
.quiz .explain.bad { border-left-color: var(--red); }
.quiz .quiz-foot { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin-top: 4px; font-family: var(--font-mono); font-size: 13px; color: var(--muted); }
.quiz .quiz-foot b { color: var(--orange); }

/* ---------- progress / badges ---------- */
.progress-card {
  display: flex; align-items: center; gap: 18px; flex-wrap: wrap;
  background: var(--surface-2); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 20px; margin: 0 0 1.4em;
}
.progress-card .txt { font-size: 13.5px; color: var(--muted); }
.progress-card .txt b { color: var(--text); font-family: var(--font-mono); }
.bar { flex: 1; min-width: 160px; height: 8px; background: var(--line); border-radius: 999px; overflow: hidden; }
.bar > i { display: block; height: 100%; width: 0%; background: linear-gradient(90deg, var(--orange), var(--yellow)); border-radius: 999px; transition: width 0.35s ease; }
.mod-complete {
  display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap;
  margin-top: 28px; padding: 18px 20px; border: 1px dashed var(--line-strong); border-radius: var(--radius);
  background: var(--surface);
}
.mod-complete.done { border-style: solid; border-color: color-mix(in srgb, var(--green) 50%, var(--line)); background: var(--green-soft); }
.mod-complete .txt { font-size: 14px; color: var(--muted); }
.mod-complete .txt b { color: var(--text); }
.badges { display: flex; flex-wrap: wrap; gap: 10px; }
.badge {
  display: inline-flex; align-items: center; gap: 8px; font-size: 12.5px; padding: 6px 12px 6px 8px;
  border: 1px solid var(--line); border-radius: 999px; background: var(--surface); color: var(--faint);
}
.badge .b-ic { width: 22px; height: 22px; border-radius: 50%; display: grid; place-items: center; background: var(--surface-3); font-size: 12px; }
.badge.earned { color: var(--text); border-color: color-mix(in srgb, var(--orange) 45%, var(--line)); }
.badge.earned .b-ic { background: var(--orange-soft); color: var(--orange); }

/* toast */
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%) translateY(10px);
  background: var(--text); color: var(--bg); font-size: 14px; font-weight: 600; padding: 12px 18px; border-radius: 12px;
  box-shadow: var(--shadow-lift); opacity: 0; pointer-events: none; transition: opacity 0.2s, transform 0.2s; z-index: 60; max-width: 90vw;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* confetti canvas */
#sp-confetti { position: fixed; inset: 0; pointer-events: none; z-index: 55; }

/* ---------- module map (index) ---------- */
.mod-map { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; margin: 0 0 1.6em; }
.mod-card {
  display: flex; flex-direction: column; gap: 10px; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 18px 18px 16px; text-decoration: none; color: var(--text); box-shadow: var(--shadow);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.mod-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lift); border-color: var(--line-strong); }
.mod-card .mc-top { display: flex; align-items: center; gap: 10px; }
.mod-card .mc-idx { width: 36px; height: 36px; border-radius: 10px; background: var(--orange-soft); color: var(--orange); font-family: var(--font-display); font-weight: 800; display: grid; place-items: center; font-size: 16px; flex-shrink: 0; }
.mod-card .mc-week { font-family: var(--font-mono); font-size: 11px; color: var(--faint); text-transform: uppercase; letter-spacing: 0.1em; }
.mod-card h3 { font-size: 16.5px; }
.mod-card p { font-size: 13.5px; color: var(--muted); margin: 0; }
.mod-card .mc-foot { display: flex; align-items: center; gap: 8px; margin-top: auto; padding-top: 6px; font-family: var(--font-mono); font-size: 11.5px; color: var(--faint); }
.mod-card.done { border-color: color-mix(in srgb, var(--green) 45%, var(--line)); }
.mod-card.done .mc-idx { background: var(--green-soft); color: var(--green); }
.mod-card .mc-status { margin-left: auto; }

/* ---------- prev / next ---------- */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 34px; }
@media (max-width: 600px) { .pager { grid-template-columns: 1fr; } }
.pager a { display: block; text-decoration: none; color: var(--text); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 14px 16px; background: var(--surface); }
.pager a:hover { border-color: var(--line-strong); box-shadow: var(--shadow); }
.pager a .pg-k { font-family: var(--font-mono); font-size: 11px; color: var(--faint); text-transform: uppercase; letter-spacing: 0.1em; }
.pager a .pg-t { font-weight: 600; margin-top: 3px; }
.pager a.next { text-align: right; }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--line); color: var(--faint); font-size: 13px; padding: 32px 0 56px; }
.site-footer .wrap { display: flex; flex-wrap: wrap; gap: 18px 40px; justify-content: space-between; }
.site-footer p { margin: 0; max-width: 60ch; }

/* ---------- misc ---------- */
.hero { padding: 52px 0 32px; }
.hero .kicker { color: var(--orange); }
.center { text-align: center; }
.tabular { font-variant-numeric: tabular-nums; }
.sr-only { position: absolute; left: -9999px; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}
@media print {
  .topbar, .toc, .pager, .mod-complete, .site-footer, .theme-btn { display: none !important; }
  .page { grid-template-columns: 1fr; padding: 0; }
  body { background: #fff; color: #000; }
}

/* Learning path and notebook share the course's existing tokens. */
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 100; padding: 12px 18px; background: var(--text); color: var(--bg); }
.skip-link:focus { top: 8px; }
.learning-page { padding-top: 42px; padding-bottom: 72px; }
.learning-page > section { margin-top: 38px; }
.learning-page h2 { margin-bottom: 18px; }
.next-session { margin: 26px 0 20px; border-left: 4px solid var(--orange); }
.next-session p:last-child { margin-bottom: 0; margin-top: 10px; color: var(--muted); font-size: 14px; }
.resume-link { font-family: var(--font-display); font-weight: 700; font-size: 20px; }
.route-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.route-grid h3 { font-size: 21px; margin-bottom: 12px; }
.route-links { list-style: none; padding: 0; margin: 16px 0 0; }
.route-links a { display: block; padding: 8px 0; border-top: 1px solid var(--line); }
.notebook-form { display: grid; gap: 10px; margin: 24px 0; }
.notebook-form label { font-weight: 600; margin-top: 10px; }
.notebook-form input, .notebook-form select, .notebook-form textarea { font: inherit; width: 100%; min-width: 0; color: var(--text); background: var(--surface-2); border: 1px solid var(--line-strong); border-radius: 8px; padding: 10px 12px; }
.notebook-form textarea { resize: vertical; }
.notebook-form p { margin-bottom: 0; font-size: 14px; color: var(--muted); }
.import-control { display: grid; gap: 12px; margin-top: 24px; }
.import-control input { max-width: 100%; }
.source-note { font-size: 13px; color: var(--muted); border-top: 1px solid var(--line); padding-top: 14px; line-height: 1.7; }
main.page:has(> .content:only-child) { grid-template-columns: minmax(0, 1fr); max-width: 850px; }
.btn, .icon-btn, .theme-btn { min-height: 40px; }
.topbar .brand { flex-shrink: 0; }
@media (max-width: 1100px) { .nav-progress { display: none; } }
@media (max-width: 860px) {
  .topnav { display: none; position: absolute; left: 0; right: 0; top: 100%; flex-direction: column; background: var(--surface); border-bottom: 1px solid var(--line); padding: 8px 12px 12px; box-shadow: var(--shadow-lift); }
  .topnav.open { display: flex; }
  .topnav a { padding: 10px; font-size: 15px; }
  .nav-toggle { display: inline-flex; margin-left: auto; }
  .topbar-inner { position: relative; }
}
@media (max-width: 600px) {
  .route-grid { grid-template-columns: 1fr; }
  .flip { white-space: normal; overflow-wrap: anywhere; }
  .ruler .marker:nth-last-child(2)::after { bottom: 72px; }
  .ruler-head { margin-bottom: 42px; }
}