/* =========================================================
   Virtual Laboratories – site styles
   Brand: slate #35424a + orange #e8491d
   ========================================================= */

/* ---------- Tokens ---------- */
:root {
  color-scheme: light;

  --brand: #35424a;
  --accent: #e8491d;
  --accent-hover: #c63c14;
  --accent-ink: #b8380f;          /* orange text on light surfaces */
  --btn-primary: #d6431a;

  --bg: #f3f5f6;
  --surface: #ffffff;
  --surface-2: #eef1f3;
  --text: #1c2327;
  --text-2: #4a5861;
  --text-muted: #6b7880;
  --border: #dde2e5;
  --shadow: 0 1px 2px rgba(20, 30, 36, 0.06), 0 6px 18px rgba(20, 30, 36, 0.06);
  --figure-bg: #ffffff;

  --radius: 12px;
  --radius-sm: 8px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  /* charts */
  --chart-text: #4a5861;
  --chart-grid: #e7eaec;
  --chart-axis: #c3cbd0;
  --series-1: #2a78d6;
  --series-2: #eb6834;
  --series-3: #1baf7a;
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;

    --brand: #252f35;
    --accent: #f05a2c;
    --accent-hover: #ff7044;
    --accent-ink: #ff8c60;
    --btn-primary: #dd4c1f;

    --bg: #111619;
    --surface: #1a2125;
    --surface-2: #222b30;
    --text: #e6eaed;
    --text-2: #b7c2c9;
    --text-muted: #8d9aa3;
    --border: #2d383e;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.35), 0 6px 18px rgba(0, 0, 0, 0.25);
    --figure-bg: #f1f3f4;

    --chart-text: #b7c2c9;
    --chart-grid: #263036;
    --chart-axis: #3b474e;
    --series-1: #3987e5;
    --series-2: #d95926;
    --series-3: #199e70;
  }
}

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

[hidden] { display: none !important; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font: 16px/1.6 var(--font);
  background: var(--bg);
  color: var(--text);
  -webkit-text-size-adjust: 100%;
}

main { flex: 1; }

img { max-width: 100%; height: auto; }

a { color: var(--accent-ink); }

h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 0.5em; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.container { width: min(1140px, 100% - 32px); margin-inline: auto; }
.container--wide { width: min(1480px, 100% - 32px); margin-inline: auto; }

/* ---------- Header ---------- */
.site-header {
  background: var(--brand);
  color: #fff;
  border-bottom: 3px solid var(--accent);
}

.site-header .container,
.site-header .container--wide {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px 24px;
  padding-block: 18px;
}

.brand {
  color: #fff;
  text-decoration: none;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand .highlight { color: var(--accent); }

.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.site-nav a {
  display: block;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: #d9e1e5;
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.site-nav a:hover { color: #fff; background: rgba(255, 255, 255, 0.08); }
.site-nav .current a { color: #fff; box-shadow: inset 0 -2px 0 var(--accent); border-radius: 0; }

/* ---------- Footer ---------- */
.site-footer {
  margin-top: 56px;
  padding: 18px 16px;
  background: var(--brand);
  border-top: 3px solid var(--accent);
  color: #c9d3d8;
  text-align: center;
  font-size: 0.875rem;
}
.site-footer p { margin: 0; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 10px 18px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s, color 0.15s, opacity 0.15s;
}
.btn-primary { background: var(--btn-primary); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }
.btn-secondary { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn-secondary:hover:not(:disabled) { border-color: var(--text-muted); }
.btn-light { background: #fff; color: #1c2327; }
.btn-light:hover { background: #f1f1f1; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

/* ---------- Cards & sections ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.section { padding-block: 48px 0; }
.section-title { text-align: center; font-size: 1.6rem; margin-bottom: 8px; }
.section-lead { text-align: center; color: var(--text-2); margin: 0 auto 32px; max-width: 640px; }

/* ---------- Home: hero ---------- */
.hero {
  padding-block: clamp(72px, 12vw, 150px);
  text-align: center;
  color: #fff;
  background:
    linear-gradient(rgba(22, 30, 35, 0.74), rgba(22, 30, 35, 0.62)),
    url("../img/showcase.jpg") center / cover no-repeat;
}
.hero h1 { font-size: clamp(1.9rem, 4.6vw, 3.1rem); margin-bottom: 16px; letter-spacing: -0.02em; }
.hero p { max-width: 720px; margin: 0 auto 28px; font-size: 1.125rem; color: #e1e7ea; }

/* ---------- Home: lab cards ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
  gap: 24px;
}

.lab-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 28px 24px;
  text-align: center;
  transition: transform 0.15s, box-shadow 0.15s;
}
.lab-card:hover { transform: translateY(-3px); }
.lab-card h3 { margin: 0; font-size: 1.15rem; }
.lab-card h3 a { color: var(--text); text-decoration: none; }
.lab-card h3 a:hover { color: var(--accent-ink); }
.lab-card p { margin: 0; flex: 1; color: var(--text-2); }

.lab-thumb {
  width: 96px;
  height: 96px;
  object-fit: cover;
  border-radius: 50%;
  box-shadow: 0 0 0 4px var(--surface), 0 0 0 5px var(--border), var(--shadow);
}

.actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; margin-top: 8px; }

/* ---------- Labs page: rows ---------- */
.lab-list { display: grid; gap: 16px; list-style: none; margin: 0; padding: 0; }

.lab-row {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 20px;
  padding: 20px 24px;
}
.lab-row h2 { font-size: 1.2rem; margin: 0 0 4px; }
.lab-row p { margin: 0; color: var(--text-2); }
.lab-row .actions { margin: 0; justify-content: flex-end; }

@media (max-width: 720px) {
  .lab-row { grid-template-columns: 1fr; text-align: center; justify-items: center; }
  .lab-row .actions { justify-content: center; }
}

/* ---------- Page head (inner pages) ---------- */
.page-head { padding-block: 40px 8px; }
.page-head h1 { font-size: clamp(1.6rem, 3.6vw, 2.2rem); margin-bottom: 8px; letter-spacing: -0.01em; }
.page-head p { margin: 0; color: var(--text-2); max-width: 720px; }
.eyebrow {
  margin: 0 0 6px !important;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-ink) !important;
}
.page-head .actions { justify-content: flex-start; margin-top: 18px; }

/* ---------- Prose (theory / about) ---------- */
.prose { max-width: 800px; margin-inline: auto; }
.prose > * + * { margin-top: 0; }
.prose p, .prose ul, .prose ol { margin: 0 0 1.1em; color: var(--text); }
.prose h2 {
  margin: 2.2em 0 0.6em;
  padding-top: 0.2em;
  font-size: 1.45rem;
  scroll-margin-top: 16px;
}
.prose h3 { margin: 1.8em 0 0.5em; font-size: 1.15rem; }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose li + li { margin-top: 0.35em; }

.diagram {
  margin: 1.6em auto;
  padding: 16px;
  background: var(--figure-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-align: center;
}
.diagram img { display: block; margin-inline: auto; }
.diagram figcaption { margin-top: 10px; font-size: 0.875rem; color: #4a5861; }

.equation {
  margin: 1.2em 0;
  padding: 14px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  overflow-x: auto;
}
.equation .katex-display { margin: 0.4em 0; }

.back-to-top { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px; margin-top: 32px; }

/* About page bits */
.chips { display: flex; flex-wrap: wrap; gap: 8px; list-style: none; padding: 0 !important; }
.chips li { margin: 0 !important; padding: 4px 12px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--border); font-size: 0.9rem; }
.refs li { color: var(--text-2); }

/* ---------- Contact ---------- */
.form-card { max-width: 560px; margin: 24px auto 0; padding: 28px; }
.field { display: grid; gap: 6px; margin-bottom: 16px; }
.field label { font-weight: 600; font-size: 0.95rem; }

input[type="text"], input[type="email"], input[type="number"], textarea {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  font: inherit;
}
textarea { min-height: 140px; resize: vertical; }
input:disabled { opacity: 0.6; }

.notice {
  max-width: 560px;
  margin: 16px auto 0;
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  border: 1px solid #0ca30c;
  background: rgba(12, 163, 12, 0.08);
  font-weight: 600;
}
.notice--error { border-color: #d03b3b; background: rgba(208, 59, 59, 0.08); }

/* ---------- Simulators ---------- */
.sim-layout {
  display: grid;
  grid-template-columns: minmax(300px, 390px) minmax(0, 1fr);
  grid-template-areas: "controls viewport";
  gap: 20px;
  align-items: start;
  margin-top: 20px;
}
.sim-layout > .parameters { grid-area: controls; }
.sim-layout > .scene,
.sim-layout > .sim-output { grid-area: viewport; }

.scene {
  position: sticky;
  top: 16px;
  height: clamp(360px, 70vh, 640px);
  overflow: hidden;
  border-radius: var(--radius);
  background: radial-gradient(ellipse at 50% 35%, #1f2c33 0%, #0b0f12 72%);
  box-shadow: var(--shadow);
}
.scene canvas { display: block; }

.scene-hint {
  position: absolute;
  left: 12px;
  bottom: 12px;
  padding: 5px 10px;
  border-radius: 999px;
  background: rgba(0, 0, 0, 0.45);
  color: #cfd8dc;
  font-size: 0.78rem;
  pointer-events: none;
}

/* control panel */
.parameters { overflow: hidden; }
.parameters > div + div { border-top: 1px solid var(--border); }

.ranges {
  display: grid;
  grid-template-columns: 8.5rem minmax(0, 1fr) 5.25rem;
  align-items: center;
  gap: 10px 10px;
  margin: 0;
  padding: 14px 18px;
}
.ranges > p {
  grid-column: 1 / -1;
  margin: 0;
  font-size: 0.75rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.ranges br { display: none; }
.ranges label { font-size: 0.92rem; color: var(--text-2); }
.ranges input[type="number"] { padding: 5px 8px; font-variant-numeric: tabular-nums; }

input[type="range"] { width: 100%; margin: 0; accent-color: var(--accent); }

.buttons {
  display: grid;
  gap: 8px;
  padding: 16px 18px 18px;
  counter-reset: step;
  background: var(--surface-2);
}
.buttons .btn { width: 100%; justify-content: flex-start; }
.buttons .btn::before {
  counter-increment: step;
  content: counter(step);
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.24);
  font-size: 0.78rem;
}

.progress { position: relative; height: 6px; margin-top: 24px; }

/* result tiles */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 12px;
  margin-top: 24px;
}
.stats > div {
  display: none;
  padding: 14px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.stat-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.stat-value { display: block; font-size: 1.45rem; font-weight: 650; }

.graph {
  display: none;
  width: 100%;
  height: 460px;
  margin-top: 16px;
  padding: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* transmission: results table + graph grid */
.panel-title { font-size: 1.05rem; margin: 0 0 4px; }
.results-card { padding: 20px; }
.empty-state { color: var(--text-2); margin: 0; }

.table-scroll { overflow-x: auto; margin-top: 12px; }
.results-table { width: 100%; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.results-table th, .results-table td {
  padding: 9px 12px;
  text-align: right;
  white-space: nowrap;
  border-bottom: 1px solid var(--border);
}
.results-table thead th { font-size: 0.85rem; color: var(--text-2); }
.results-table tbody th { text-align: left; font-weight: 600; }
.results-table tbody tr:last-child > * { border-bottom: 0; }
.results-table tbody tr:hover { background: var(--surface-2); }

.swatch { display: inline-block; width: 10px; height: 10px; margin-right: 6px; border-radius: 2px; vertical-align: 0; }
.swatch-1 { background: var(--series-1); }
.swatch-2 { background: var(--series-2); }
.swatch-3 { background: var(--series-3); }

.graph-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 520px), 1fr));
  gap: 16px;
  margin-top: 24px;
}
.graph-grid > .graph { height: 400px; margin-top: 0; }

@media (max-width: 900px) {
  .sim-layout { grid-template-columns: minmax(0, 1fr); grid-template-areas: "viewport" "controls"; }
  .sim-layout--table { grid-template-areas: "controls" "viewport"; }
  .scene { position: relative; top: 0; height: 340px; }
  .graph { height: 380px; }
}