/* Shared theme for SEES:4800 interactive demos.
   Light by default; dark when the visitor's browser/OS prefers dark.
   Canvas colors are read from these CSS variables by demo-theme.js,
   so a single palette drives both the page chrome and the drawings. */

:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-2: #f1f5f9;
  --canvas-bg: #ffffff;
  --border: #e2e8f0;
  --text: #0f172a;
  --text-muted: #5b6b82;
  --grid: #e5eaf1;

  --c-primary: #0284c7;   /* readable on light */
  --c-primary-bright: #0ea5e9;
  --c-primary-soft: rgba(2, 132, 199, 0.10);
  --c-accent: #d97706;
  --c-accent-bright: #f59e0b;
  --c-danger: #dc2626;
  --c-success: #059669;

  --shadow: 0 1px 2px rgba(15, 23, 42, .06), 0 8px 24px rgba(15, 23, 42, .06);
  --radius: 14px;
  --font: "Inter", "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a;
    --surface: #1e293b;
    --surface-2: #162032;
    --canvas-bg: #0b1220;
    --border: #334155;
    --text: #f1f5f9;
    --text-muted: #94a3b8;
    --grid: #233046;

    --c-primary: #38bdf8;
    --c-primary-bright: #38bdf8;
    --c-primary-soft: rgba(56, 189, 248, 0.12);
    --c-accent: #fbbf24;
    --c-accent-bright: #fbbf24;
    --c-danger: #f87171;
    --c-success: #4ade80;

    --shadow: 0 4px 6px rgba(0, 0, 0, .3);
  }
}

* { box-sizing: border-box; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  margin: 0;
}

/* Sticky course navigation bar injected at the top of every tool */
.course-nav-bar {
  position: sticky;
  top: 0;
  z-index: 2000;
  display: flex;
  gap: 1.4rem;
  align-items: center;
  padding: .5rem 1.1rem;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  font-size: .85rem;
}
.course-nav-bar a { color: var(--text-muted); text-decoration: none; font-weight: 600; }
.course-nav-bar a:hover { color: var(--c-primary); }
.course-nav-bar .spacer { margin-left: auto; color: var(--text-muted); opacity: .8; }

header.demo-header {
  text-align: center;
  padding: 2.4rem 1rem 1.6rem;
  background:
    radial-gradient(1200px 200px at 50% -40px, var(--c-primary-soft), transparent),
    var(--bg);
  border-bottom: 1px solid var(--border);
}
header.demo-header h1 { font-size: 1.9rem; color: var(--text); margin: 0; letter-spacing: -0.01em; }
header.demo-header .subtitle { color: var(--text-muted); margin-top: .5rem; max-width: 760px; margin-inline: auto; }

.container { max-width: 1120px; margin: 0 auto; padding: 22px 20px 60px; }

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}

canvas { width: 100%; display: block; background: var(--canvas-bg); border: 1px solid var(--border); border-radius: 10px; }

.controls { display: grid; grid-template-columns: 1fr; gap: 16px; }
@media (min-width: 720px) { .controls.cols-2 { grid-template-columns: 1fr 1fr; } .controls.cols-3 { grid-template-columns: 1fr 1fr 1fr; } }

.ctrl label { display: flex; justify-content: space-between; font-weight: 600; margin-bottom: 5px; font-size: .88rem; }
.ctrl label span { color: var(--c-accent); font-variant-numeric: tabular-nums; }

input[type=range] { width: 100%; accent-color: var(--c-primary); }

.seg { display: inline-flex; border: 1px solid var(--c-primary); border-radius: 9px; overflow: hidden; margin-top: 4px; }
.seg button { background: transparent; color: var(--text); border: none; padding: 8px 16px; cursor: pointer; font-weight: 600; font-size: .88rem; }
.seg button.active { background: var(--c-primary); color: #fff; }

.preset { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.preset button { background: var(--surface-2); border: 1px solid var(--c-primary); color: var(--text); border-radius: 8px; padding: 7px 13px; cursor: pointer; font-size: .85rem; font-weight: 500; }
.preset button:hover { background: var(--c-primary); color: #fff; }

.readout { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 16px; }
.stat { background: var(--surface-2); border: 1px solid var(--border); border-radius: 10px; padding: 13px; text-align: center; }
.stat .v { font-size: 1.35rem; font-weight: 700; color: var(--c-primary); font-variant-numeric: tabular-nums; }
.stat .l { font-size: .72rem; color: var(--text-muted); margin-top: 2px; }
.stat.match .v { color: var(--c-success); }

.formula { background: var(--c-primary-soft); border-left: 4px solid var(--c-primary); padding: 13px 16px; margin-top: 16px; border-radius: 8px; font-size: .92rem; }
.note { background: color-mix(in srgb, var(--c-accent) 12%, transparent); border-left: 4px solid var(--c-accent); padding: 11px 15px; margin-top: 14px; border-radius: 8px; font-size: .85rem; color: var(--text-muted); }

.btn { background: var(--surface-2); border: 1px solid var(--c-accent); color: var(--c-accent); border-radius: 8px; padding: 8px 16px; cursor: pointer; font-weight: 600; }
.btn:hover { background: var(--c-accent); color: #fff; }

h3 { color: var(--c-accent); margin: 6px 0; }
.hint { color: var(--text-muted); font-size: .85rem; margin-bottom: 10px; }
.legend { display: flex; flex-wrap: wrap; gap: 14px; margin-bottom: 12px; font-size: .85rem; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend .sw { width: 24px; height: 4px; border-radius: 2px; display: inline-block; }

/* Course-wide usability and accessibility helpers. */
:where(a, button, input, select, textarea, [tabindex]):focus-visible {
  outline: 3px solid var(--c-accent-bright, #f59e0b);
  outline-offset: 3px;
}

:where(button, select, input[type="number"], input[type="text"]) {
  min-height: 44px;
}

button { touch-action: manipulation; }

table {
  max-width: 100%;
}

.table-scroll {
  width: 100%;
  overflow-x: auto;
  overscroll-behavior-inline: contain;
}

.learning-objectives,
.level-card,
.science-caveat {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 18px;
  margin: 16px 0;
  background: var(--surface-2);
}

.learning-objectives h2,
.level-card h3,
.science-caveat h3 {
  margin-top: 0;
}

.level-badge {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 3px 9px;
  border-radius: 999px;
  border: 1px solid currentColor;
  color: var(--c-primary);
  font-size: .72rem;
  font-weight: 800;
  letter-spacing: .04em;
  text-transform: uppercase;
}

.level-badge.graduate { color: var(--c-accent); }

.science-caveat {
  border-left: 4px solid var(--c-accent);
  color: var(--text-muted);
}

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

@media (max-width: 640px) {
  .course-nav-bar {
    position: relative;
    flex-wrap: wrap;
    gap: .25rem .8rem;
    padding: .35rem .7rem;
  }

  .course-nav-bar a {
    display: inline-flex;
    align-items: center;
    min-height: 44px;
  }

  .course-nav-bar .spacer { width: 100%; margin-left: 0; }
  header.demo-header { padding: 1.6rem .85rem 1.1rem; }
  header.demo-header h1 { font-size: 1.55rem; }
  .container { padding: 14px 12px 42px; }
  .panel { padding: 15px; }
  .readout { grid-template-columns: 1fr; }
  .formula { overflow-x: auto; }
}