/* FTIR Interferometer Explorer stylesheet, begun as a copy of the Millikan Oil Drop Lab stylesheet. House tokens and
   components follow the analyticalchem style guide; this page's own layout lives in css/page.css. */

/* ---------- Tokens ---------- */
:root {
  color-scheme: light;
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --surface-2: #f3f2ee;
  --text-primary: #0b0b0b;
  --text-secondary: #52514e;
  --text-muted: #6f6d68;
  --grid: #e1e0d9;
  --axis: #c3c2b7;
  --border: rgba(11, 11, 11, 0.10);
  --border-strong: var(--text-muted);      /* boundaries that identify a control (3:1) */
  --accent: #2670cc;                       /* white text 4.9:1 */
  --accent-ink: #ffffff;

  --series-a: #149a6a;                     /* 3.5:1 on surface */
  --series-b: #eb6834;                     /* 3.1:1 */
  --series-c: #2a78d6;                     /* 4.3:1 */
  --series-d: #4a3aa7;                     /* 8.3:1 */

  --status-good: #0ca30c;
  --status-warning: #fab219;               /* graphics only, never text */
  --status-critical: #d03b3b;
  --success-text: #006300;
  --critical-text: #d03b3b;

  --chart-font-small: 11px;                /* drawn text and line sizes, read by drawing code */
  --chart-font: 12px;
  --chart-line: 2px;
  --chart-line-total: 2.5px;
  --chart-marker: 5px;
  --chart-halo: 4px;

  --radius: 12px;
  --font: system-ui, -apple-system, "Segoe UI", sans-serif;

  /* The instrument drawing. Fills are decorative; every part has an outline in --part-wall (the muted
     text colour, 4.6:1 or better on the surfaces it sits on), which carries the 3:1 boundary. The
     marks that mean something sit on the surface colour: the beam line is --text-primary, the
     waves --wave-fixed, --series-c and --text-primary, the signal bar --accent (4.8:1). */
  --part-wall: var(--text-muted);
  --mirror: #d9dee3;
  --glass: #bcd8ee;                        /* beamsplitter and salt windows */
  --liquid: #a9cfe9;
  --film: #eadfb4;
  --card-stock: #dedcd3;
  --gas: #e3eee5;
  --glow: #f2a66f;                         /* the source */
  --glow-core: #eb6834;
  --detector: #8a8880;
  --beam-band: rgba(235, 104, 52, 0.16);
  --wave-fixed: #c4501f;                   /* 4.5:1 on surface, 3.8:1 on the beam band */
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --page: #0d0d0d;
    --surface: #1a1a19;
    --surface-2: #232321;
    --text-primary: #ffffff;
    --text-secondary: #c3c2b7;
    --text-muted: #9a988f;
    --grid: #2c2c2a;
    --axis: #45443f;
    --border: rgba(255, 255, 255, 0.10);
    --accent: #3987e5;
    --accent-ink: #0b0b0b;                 /* dark ink on the brighter accent: 5.4:1 */
    --series-a: #199e70;
    --series-b: #d95926;
    --series-c: #3987e5;
    --series-d: #9085e9;
    --success-text: #0ca30c;
    --critical-text: #ef6a63;
    --mirror: #5d646b;
    --glass: #3c5f80;
    --liquid: #2f5d80;
    --film: #6d6440;
    --card-stock: #3a3a37;
    --gas: #2a3a2e;
    --glow: #b8522a;
    --glow-core: #f08a4b;
    --detector: #6a6a65;
    --beam-band: rgba(217, 89, 38, 0.24);
    --wave-fixed: #e8672f;                 /* 5.3:1 on surface, 4.0:1 on the beam band */
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #0d0d0d;
  --surface: #1a1a19;
  --surface-2: #232321;
  --text-primary: #ffffff;
  --text-secondary: #c3c2b7;
  --text-muted: #9a988f;
  --grid: #2c2c2a;
  --axis: #45443f;
  --border: rgba(255, 255, 255, 0.10);
  --accent: #3987e5;
  --accent-ink: #0b0b0b;
  --series-a: #199e70;
  --series-b: #d95926;
  --series-c: #3987e5;
  --series-d: #9085e9;
  --success-text: #0ca30c;
  --critical-text: #ef6a63;
  --mirror: #5d646b;
  --glass: #3c5f80;
  --liquid: #2f5d80;
  --film: #6d6440;
  --card-stock: #3a3a37;
  --gas: #2a3a2e;
  --glow: #b8522a;
  --glow-core: #f08a4b;
  --detector: #6a6a65;
  --beam-band: rgba(217, 89, 38, 0.24);
  --wave-fixed: #e8672f;
}

/* ---------- Series keys ---------- */

.lg-key { display: inline-block; flex: none; width: 26px; height: 3px; border-radius: 2px; background: var(--key); vertical-align: middle; }
.lg-key.thick { height: 5px; }
.lg-key.dashed { height: 0; border-radius: 0; background: none; border-top: 3px dashed var(--key); }
.lg-key.dotted { height: 0; border-radius: 0; background: none; border-top: 3px dotted var(--key); }
.lg-wash { display: inline-block; flex: none; width: 22px; height: 14px; border-radius: 2px; background: color-mix(in srgb, var(--key) 22%, transparent); border: 1px solid var(--key); }
.lg-dot { display: inline-block; flex: none; width: 12px; height: 12px; border-radius: 50%; background: var(--key); }
.lg-dot.hollow { background: var(--surface); border: 2px solid var(--key); }

/* ---------- Base ---------- */

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--page);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.9375rem;
  line-height: 1.5;
}

h1, h2, h3 { line-height: 1.2; margin: 0; }
h1 { font-size: 2.6rem; font-weight: 750; letter-spacing: -0.02em; line-height: 1.1; }
/* Panel titles: title case, bold, and the largest text inside each panel. */
h2 { font-size: 1.4rem; font-weight: 700; letter-spacing: -0.005em; }
h3 { font-size: 0.95rem; font-weight: 620; margin: 1rem 0 0.35rem; }

a { color: inherit; }

/* Subscripts keep the line height steady and stop shrinking at 0.75rem, the smallest text size allowed. */
sub { font-size: max(78%, 0.75rem); line-height: 0; vertical-align: -0.24em; }
sup { font-size: max(78%, 0.75rem); line-height: 0; }

:is(a, button, input, select, summary, [tabindex]):focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute; left: 16px; top: -100px; padding: 8px 12px;
  background: var(--accent); color: var(--accent-ink); border-radius: 8px; font-weight: 600;
}
.skip-link:focus { top: 16px; z-index: 10; outline: 2px solid var(--text-primary); outline-offset: 2px; }

.nowrap { white-space: nowrap; }
[hidden] { display: none !important; }

/* ---------- Header ---------- */

.site-header, main, .site-footer {
  max-width: 1200px;
  margin: 0 auto;
  padding-left: 24px;
  padding-right: 24px;
}

.site-header { padding-top: 28px; padding-bottom: 12px; }

main { display: grid; gap: 16px; }

.title-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}
.header-actions { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px; }

.eyebrow {
  margin: 0 0 6px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-secondary);
}
.title-rule { display: flex; gap: 4px; width: 260px; max-width: 100%; margin-top: 12px; }
.title-rule span { flex: 1; height: 5px; border-radius: 1px; background: var(--series-a); }
.title-rule span:nth-child(2) { background: var(--series-b); }
.title-rule span:nth-child(3) { background: var(--series-c); }

.lede { margin: 12px 0 0; color: var(--text-secondary); max-width: 62ch; }
.present-hint { display: none; }
.hint { margin: 8px 0 0; font-size: 0.85rem; color: var(--text-muted); }

/* ---------- Cards ---------- */

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  min-width: 0;
}

.card-head { margin-bottom: 12px; }
.card-sub { margin: 4px 0 0; font-size: 0.85rem; color: var(--text-secondary); }

/* Frames: solid for panels you set or watch, dashed for computed results. */
.controls, .visual-card { border: 2px solid var(--text-muted); }
.chart-card, .results { border: 2px dashed var(--text-muted); }

/* ---------- Controls ---------- */

.sliders {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px 28px;
}

.control { min-width: 0; }
.control-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 8px;
}

.control label, .control .label { font-weight: 600; }
.control output { font-variant-numeric: tabular-nums; color: var(--text-primary); font-weight: 600; white-space: nowrap; }

input[type="range"] {
  width: 100%;
  margin: 10px 0 4px;
  accent-color: var(--accent);
  height: 24px;
}
input[type="range"]:disabled { opacity: 0.4; cursor: not-allowed; }

.control-sub { margin: 0; font-size: 0.82rem; color: var(--text-secondary); }

.run-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 18px;
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--grid);
}

.btn {
  padding: 7px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface-2);
  color: var(--text-primary);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}
.btn:hover { filter: brightness(0.97); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.btn.ghost { background: transparent; font-weight: 500; font-size: 0.85rem; color: var(--text-secondary); white-space: nowrap; }
.btn.ghost[aria-pressed="true"] { background: var(--text-primary); color: var(--surface); border-color: transparent; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; filter: none; }

/* Preset chips and position switches: the matching one is filled (7.3). */
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  padding: 2px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text-secondary);
  font: inherit;
  font-size: 0.8rem;
  cursor: pointer;
}
.chip:hover { background: var(--surface-2); }
.chip[aria-pressed="true"] { background: var(--text-primary); color: var(--surface); border-color: transparent; }

select {
  font: inherit;
  padding: 5px 8px;
  border-radius: 8px;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  color: var(--text-primary);
  max-width: 100%;
}
select option:disabled { color: var(--text-muted); }
.select { display: inline-flex; align-items: center; gap: 8px; color: var(--text-secondary); font-size: 0.9rem; }

.check { display: inline-flex; align-items: center; gap: 6px; font-size: 0.9rem; color: var(--text-secondary); cursor: pointer; }
.check input { accent-color: var(--accent); width: 16px; height: 16px; margin: 0; }

/* Typed number boxes: the frame is what identifies the field, so it uses --border-strong (7.4). */
.entry { display: inline-flex; flex: none; align-items: baseline; gap: 5px; white-space: nowrap; }
.num {
  width: 5.4em; padding: 1px 6px; font: inherit; font-weight: 600; font-variant-numeric: tabular-nums; text-align: right;
  color: var(--text-primary); background: var(--surface); border: 1px solid var(--border-strong); border-radius: 6px;
}
.num:disabled { opacity: 0.4; cursor: not-allowed; }
.num[aria-invalid="true"] { border-color: var(--critical-text); box-shadow: 0 0 0 1px var(--critical-text); }
.entry .unit { color: var(--text-secondary); font-weight: 600; }
.num-msg { margin: 2px 0 0; font-size: 0.82rem; font-weight: 600; color: var(--critical-text); }
.num-msg:empty { margin: 0; }

/* ---------- Visuals ---------- */

/* Heights live in --h so presentation mode can scale them. */
.visual { display: block; width: 100%; height: var(--h); }

/* Legends are a grid, one entry per cell, so the entries line up in columns and a long
   entry wraps inside its own cell. Each swatch sits in a 26 px column, centred on the
   entry's first line. Style guide 7.10. */
.legend {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 13rem), 1fr));
  gap: 6px 20px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
  font-size: 0.875rem;
  line-height: 1.35;
  color: var(--text-primary);
}
.legend + .legend { margin-top: 6px; }
.lg { display: grid; grid-template-columns: 26px minmax(0, 1fr); column-gap: 10px; align-items: start; }
.lg[hidden] { display: none; }
.lg > :first-child { justify-self: center; }
.lg > .lg-key { margin-top: calc(0.675em - 1.5px); }
.lg > .lg-key.thick { margin-top: calc(0.675em - 2.5px); }
.lg > .lg-wash { margin-top: calc(0.675em - 7px); }
.lg > .lg-dot { margin-top: calc(0.675em - 6px); }
.legend-note { margin: 6px 0 0; font-size: 0.85rem; color: var(--text-secondary); }

.tooltip {
  position: absolute; pointer-events: none; min-width: 170px; padding: 8px 10px; background: var(--surface);
  border: 1px solid var(--border); border-radius: 8px; box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12); font-size: 0.8rem; z-index: 2;
  color: var(--text-primary);
}
.tooltip[hidden] { display: none; }

/* ---------- Chart and results ---------- */

.grid-2 {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: 16px;
}

/* Positioned, so a visually hidden caption or header label inside the table stays in the scroll box
   instead of widening the page. */
.table-scroll { position: relative; overflow-x: auto; margin-top: 8px; }
table { border-collapse: collapse; width: 100%; font-variant-numeric: tabular-nums; font-size: 0.85rem; }
th, td { padding: 5px 8px; text-align: right; border-bottom: 1px solid var(--grid); white-space: nowrap; }
th { color: var(--text-secondary); font-weight: 600; }
th.text, td.text { text-align: left; white-space: normal; }

.results { display: flex; flex-direction: column; gap: 16px; }

/* Hierarchy: h2 1.4rem > tile label 1.2rem > value 1.1rem > sub-caption 0.78rem. */
.tile-label { display: block; font-size: 1.2rem; font-weight: 620; line-height: 1.25; color: var(--text-primary); }
.tiles {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 16px;
}
.tile { padding-top: 10px; border-top: 1px solid var(--grid); min-width: 0; }
.tile-value { display: block; font-size: 1.1rem; font-weight: 650; margin-top: 4px; font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.tile-sub { display: block; font-size: 0.78rem; color: var(--text-muted); margin-top: 2px; }

.verdict { margin: 0; font-size: 0.95rem; font-weight: 600; }

/* ---------- Notes and footer ---------- */

.notes summary { cursor: pointer; }
.notes summary h2 { display: inline; }
.notes-body { max-width: 80ch; color: var(--text-secondary); font-size: 0.92rem; }
.notes-body p, .notes-body ul, .notes-body ol { margin: 0.3rem 0 0.6rem; }
.notes-body h3 { color: var(--text-primary); }
.notes-body code { font-size: 0.95em; }

.site-footer { padding-top: 18px; padding-bottom: 32px; font-size: 0.8rem; color: var(--text-muted); }
.site-footer p { margin: 0 0 4px; }
.site-footer a { color: var(--text-secondary); }

/* ---------- Responsive ---------- */

@media (max-width: 980px) {
  .sliders { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-2 { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 560px) {
  .site-header, main, .site-footer { padding-left: 16px; padding-right: 16px; }
  /* Reflow at 320 px: header buttons drop below the title, value tiles stack. */
  .title-row { flex-wrap: wrap; }
  .header-actions { justify-content: flex-start; }
  .tiles { grid-template-columns: minmax(0, 1fr); }
  h1 { font-size: 2rem; }
  .title-rule { width: 200px; }
  .card { padding: 14px; }
  .sliders { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- Reduced motion ---------- */

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

/* ---------- Presentation mode ---------- */

html[data-present] .eyebrow, html[data-present] .lede, html[data-present] .hint,
html[data-present] .notes, html[data-present] .site-footer { display: none; }
html[data-present] .present-hint { display: block; margin: 12px 0 0; color: var(--text-secondary); }

@media (min-width: 900px) {
  html[data-present] { font-size: 125%; }
  html[data-present] body { font-size: 1rem; }
  html[data-present] .site-header, html[data-present] main { max-width: none; padding-left: 32px; padding-right: 32px; }
  html[data-present] main { gap: 20px; }
  html[data-present] h1 { font-size: 2.8rem; }
  html[data-present] h2, html[data-present] .notes summary { font-size: 1.5rem; }
  html[data-present] .legend, html[data-present] .control-sub,
  html[data-present] .tile-sub, html[data-present] .card-sub { font-size: 1.05rem; }
  html[data-present] .chip { padding: 6px 16px; font-size: 1rem; }
  html[data-present] input[type="range"] { height: 36px; }
  html[data-present] .check input { width: 24px; height: 24px; }
  html[data-present] .btn { padding: 12px 24px; }
  html[data-present] .visual { height: calc(var(--h) * 1.5); }
  html[data-present] .tooltip { font-size: 1rem; min-width: 220px; }
  html[data-present] :is(a, button, input, select, summary, [tabindex]):focus-visible { outline-width: 3px; outline-offset: 3px; }

  html[data-present] {
    --chart-font-small: 15px; --chart-font: 16px; --chart-line: 3px; --chart-line-total: 3.5px;
    --chart-marker: 7px; --chart-halo: 5px;
    --text-secondary: #3a3936; --text-muted: #55534f; --axis: #7f7d76; --grid: #cfcdc4;
    --series-a: #0c8259; --series-b: #bf4a1d; --series-c: #1f66c4;
    --critical-text: #a52a2a;
  }
}

@media (min-width: 900px) and (prefers-color-scheme: dark) {
  html[data-present]:not([data-theme="light"]) {
    --text-secondary: #d6d5cb; --text-muted: #b3b1a7; --axis: #8a8880; --grid: #3a3a37;
    --series-a: #22b07f; --series-b: #e8672f; --series-c: #4a93ec; --series-d: #a89ff0;
    --critical-text: #f28b85; --success-text: #40bf40;
  }
}
@media (min-width: 900px) {
  html[data-present][data-theme="dark"] {
    --text-secondary: #d6d5cb; --text-muted: #b3b1a7; --axis: #8a8880; --grid: #3a3a37;
    --series-a: #22b07f; --series-b: #e8672f; --series-c: #4a93ec; --series-d: #a89ff0;
    --critical-text: #f28b85; --success-text: #40bf40;
  }
}