/* Three coherent palettes; loaded last so every existing page follows the selection. */
:root, :root[data-theme="midnight"] {
  color-scheme: dark;
  --paper: #0d1720;
  --paper-deep: #172731;
  --card: #12222c;
  --stage: #0b151d;
  --ink: #e9eff0;
  --muted: #acbdc4;
  --accent: #87d4c2;
  --accent-hover: #b1ecdc;
  --teal: #87d4c2;
  --teal-dark: #a1dfd0;
  --rust: #e6ad84;
  --rule: #324752;
  --line: #324752;
  --control-line: #607d88;
  --soft: #223c43;
  --on-accent: #0b2426;
  --selection: #315b60;
  --header: #101c25;
  --shadow: rgb(0 0 0 / 25%);
}
:root[data-theme="graphite"] {
  color-scheme: dark;
  --paper: #19191b;
  --paper-deep: #2a292b;
  --card: #222224;
  --stage: #151517;
  --ink: #f0ede6;
  --muted: #c0bcb4;
  --accent: #dfc18c;
  --accent-hover: #f3ddb5;
  --teal: #dfc18c;
  --teal-dark: #ead0a2;
  --rust: #9ecdc4;
  --rule: #49474a;
  --line: #49474a;
  --control-line: #827d76;
  --soft: #3e3830;
  --on-accent: #272116;
  --selection: #65553d;
  --header: #1e1e20;
  --shadow: rgb(0 0 0 / 25%);
}
:root[data-theme="paper"] {
  color-scheme: light;
  --paper: #f7f5ef;
  --paper-deep: #eeeae0;
  --card: #f0f2ea;
  --stage: #fcfbf7;
  --ink: #172b32;
  --muted: #546166;
  --accent: #2f665c;
  --accent-hover: #234d45;
  --teal: #2f665c;
  --teal-dark: #234d45;
  --rust: #a15639;
  --rule: #d4d8cf;
  --line: #d4d8cf;
  --control-line: #75877c;
  --soft: #dfe8dd;
  --on-accent: #ffffff;
  --selection: #c5d7cb;
  --header: #f7f5ef;
  --shadow: rgb(23 43 50 / 8%);
}

html { background: var(--paper); }
body { background: var(--paper); color: var(--ink); }
::selection { background: var(--selection); color: var(--ink); }
.site-header { background: var(--header); }
.nav.open { background: var(--header); box-shadow: 0 12px 25px var(--shadow); }
.site-footer { background: var(--header); }
.portrait-frame::before { background: var(--soft); }
.hero-portrait > img { box-shadow: 12px 13px 0 var(--soft); }
.button { border-color: var(--control-line); }
.button.primary, .filter-button.active {
  color: var(--on-accent); background: var(--accent); border-color: var(--accent);
}
.button.primary:hover { color: var(--on-accent); background: var(--accent-hover); border-color: var(--accent-hover); }
.text-link, .pub-links a, .pub-links button, .section-links a,
.contact-email, .research-tags span { border-color: var(--control-line); }
.search-field input, .filters input, .filters select {
  border-color: var(--control-line); background: var(--stage); color: var(--ink);
}
.search-field input::placeholder, .filters input::placeholder { color: var(--muted); }
.theme-boundaries { border-color: var(--accent); background: var(--card); }
.paper-highlights, .teaching-resource { background: var(--card); border-color: var(--line); }
.result-scope { border-color: var(--line); }
.skip-link, .toast { background: var(--accent); color: var(--on-accent); box-shadow: 0 3px 16px var(--shadow); }
.katex, .katex-display { color: inherit; }

/* A compact, always available theme selector. Navigation collapses before it crowds. */
.header-inner { gap: 18px; }
.header-tools { display: flex; align-items: center; gap: 14px; flex: 0 0 auto; margin-left: auto; }
.theme-picker { display: grid; gap: 4px; font-size: 10px; line-height: 1.2; color: var(--muted); }
.theme-picker > span { letter-spacing: .1em; text-transform: uppercase; }
.theme-picker select {
  width: 108px;
  min-height: 36px;
  padding: 6px 24px 6px 10px;
  border: 1px solid var(--control-line);
  border-radius: 3px;
  background-color: var(--card);
  color: var(--ink);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.4;
}
.theme-picker select:hover { border-color: var(--accent); }
.theme-picker select:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.theme-announcement { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }

/* The earlier modular and symmetry demonstrations share the same palette. */
.interactive-panel { background: var(--card); border-color: var(--line); }
.interactive-heading h3, .interactive-control, .interactive-readout output,
.interactive-formula, .interactive-boundary strong { color: var(--ink); }
.interactive-heading > p, .interactive-readout > span, .interactive-boundary,
.interactive-motion-note, .interactive-fusion p, .fusion-cartoon .fusion-symbol { color: var(--muted); }
.interactive-stage { background: var(--stage); border-color: var(--line); }
.interactive-stage svg text { fill: var(--muted); }
.interactive-stage svg .demo-math-label { fill: var(--ink); }
.interactive-panel input[type="range"] { accent-color: var(--accent); }
.interactive-panel select { color: var(--ink); border-color: var(--control-line); background: var(--stage); }
.interactive-actions button { background: var(--stage); color: var(--accent); border-color: var(--control-line); }
.interactive-actions button:hover { background: var(--soft); border-color: var(--accent); }
.interactive-actions button[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }
.interactive-actions button:focus-visible, .interactive-panel input:focus-visible,
.interactive-panel select:focus-visible, .interactive-panel summary:focus-visible { outline-color: var(--rust); }
.interactive-readouts, .interactive-fusion { border-color: var(--line); }
.interactive-takeaway, .interactive-fusion summary { color: var(--teal-dark); }
.fusion-cartoon .anyon { background: var(--ink); color: var(--paper); }
.fusion-cartoon .anyon.one { background: var(--rust); color: var(--paper); }
.fusion-cartoon .anyon.psi { background: var(--accent); color: var(--on-accent); }
.interactive-panel noscript p { border-color: var(--control-line); }

@media (min-width: 900px) and (max-width: 1179px) {
  .menu-toggle { display: inline-flex; }
  .nav { display: none; }
  .nav.open {
    position: absolute; display: flex; flex-direction: column; align-items: stretch;
    top: 100%; left: -32px; right: -32px; padding: 12px 32px 23px;
    gap: 0; background: var(--header); border-bottom: 1px solid var(--line);
    box-shadow: 0 12px 25px var(--shadow);
  }
  .nav a { padding: 10px 0; font-size: 14px; }
  .nav a[aria-current="page"]::after, .nav a.active::after { display: none; }
}
@media (min-width: 1180px) {
  .brand { order: 1; flex: 0 0 auto; }
  .nav, .nav.open { order: 2; display: flex; gap: 19px; margin-left: auto; background: transparent; box-shadow: none; }
  .nav a { font-size: 12px; }
  .header-tools { order: 3; margin-left: 4px; }
  .menu-toggle { display: none; }
}
@media (max-width: 499px) {
  .header-inner { gap: 10px; min-height: 88px; }
  .header-tools { gap: 8px; }
  .brand { gap: 8px; }
  .brand-sub { font-size: 8px; letter-spacing: .08em; }
  .brand > span:not(.brand-mark):not(.brand-sub) { font-size: 14px; }
  .brand-mark { font-size: 22px; }
  .theme-picker select { width: 94px; padding-left: 7px; font-size: 11px; }
  .menu-toggle { font-size: 0; padding-inline: 8px; gap: 0; }
  .menu-toggle > span { font-size: 18px; }
}
@media (max-width: 359px) {
  .brand-mark { display: none; }
  .header-inner { gap: 6px; }
  .theme-picker select { width: 88px; }
}
@media print {
  :root, :root[data-theme] {
    color-scheme: light;
    --paper: #fff; --paper-deep: #f4f4f4; --card: #fff; --stage: #fff;
    --ink: #000; --muted: #333; --accent: #234d45; --accent-hover: #172b32;
    --teal: #234d45; --teal-dark: #234d45; --rust: #7a4029;
    --rule: #bbb; --line: #bbb; --control-line: #888; --soft: #eee;
    --on-accent: #fff; --header: #fff;
  }
  .header-tools { display: none !important; }
  .paper-highlights, .teaching-resource { background: white; }
}