/* Pedemy Glass (2026-10-18): frosted-glass surfaces in the style of Apple's iOS.
   Everything hangs off html.pd-glass (set in base.html); remove that class and the site is back to the flat look.
   Glass needs colour behind it, so the page gets a soft "aurora" backdrop; surfaces are translucent with a blur,
   a light top edge and a soft shadow. Interaction (tilt, spotlight, ripple, sliding thumb) is in pedemy-glass.js. */
html.pd-glass {
  --g-surface: color-mix(in srgb, var(--pd-surface) 64%, transparent);
  --g-surface-strong: color-mix(in srgb, var(--pd-surface) 82%, transparent);
  --g-edge: color-mix(in srgb, #FFFFFF 70%, transparent);
  --g-line: color-mix(in srgb, var(--pd-line) 70%, transparent);
  --g-shadow: 0 1px 2px rgba(20,35,58,.05), 0 12px 32px -14px rgba(20,35,58,.28);
  --g-shadow-lift: 0 2px 6px rgba(20,35,58,.06), 0 22px 44px -16px rgba(20,35,58,.38);
  --g-blur: 18px;
}
@media (prefers-color-scheme: dark) { html.pd-glass:not([data-theme="light"]) {
  --g-surface: rgba(23,34,52,.55); --g-surface-strong: rgba(23,34,52,.78); --g-edge: rgba(255,255,255,.13); --g-line: rgba(255,255,255,.08);
  --g-shadow: 0 1px 2px rgba(0,0,0,.35), 0 14px 36px -14px rgba(0,0,0,.7); --g-shadow-lift: 0 2px 6px rgba(0,0,0,.4), 0 26px 50px -16px rgba(0,0,0,.85); } }
html.pd-glass[data-theme="dark"] {
  --g-surface: rgba(23,34,52,.55); --g-surface-strong: rgba(23,34,52,.78); --g-edge: rgba(255,255,255,.13); --g-line: rgba(255,255,255,.08);
  --g-shadow: 0 1px 2px rgba(0,0,0,.35), 0 14px 36px -14px rgba(0,0,0,.7); --g-shadow-lift: 0 2px 6px rgba(0,0,0,.4), 0 26px 50px -16px rgba(0,0,0,.85); }
@media (prefers-reduced-transparency: reduce) { html.pd-glass { --g-surface: var(--pd-surface); --g-surface-strong: var(--pd-surface); --g-blur: 0px; } }
@media (hover: none) { html.pd-glass { --g-blur: 12px; } }

/* ---------- aurora backdrop ---------- */
html.pd-glass body { position: relative; isolation: isolate; }
html.pd-glass body::before { content: ""; position: fixed; inset: -20vmax; z-index: -1; pointer-events: none;
  background:
    radial-gradient(42vmax 42vmax at 12% 8%, color-mix(in srgb, var(--pd-cobalt) 22%, transparent), transparent 60%),
    radial-gradient(38vmax 38vmax at 88% 18%, color-mix(in srgb, var(--pd-gold) 20%, transparent), transparent 60%),
    radial-gradient(46vmax 46vmax at 60% 95%, color-mix(in srgb, #2E7D6B 16%, transparent), transparent 62%),
    var(--pd-bg);
  animation: pd-aurora 28s ease-in-out infinite alternate; }
@keyframes pd-aurora { to { transform: translate3d(3vmax, -2vmax, 0) scale(1.06); } }
@media (prefers-reduced-motion: reduce) { html.pd-glass body::before { animation: none; } }

/* ---------- the glass recipe ---------- */
html.pd-glass .topbar, html.pd-glass .pd-subject, html.pd-glass .tp-tile, html.pd-glass .pd-toolcard, html.pd-glass .card, html.pd-glass .practice,
html.pd-glass .pd-result, html.pd-glass .pd-stats, html.pd-glass .pd-pillars, html.pd-glass .pd-chart, html.pd-glass .topic-node, html.pd-glass .account-prompt,
html.pd-glass .study-options-side, html.pd-glass .study-more summary, html.pd-glass .pd-search-link, html.pd-glass .pd-theme, html.pd-glass .pd-chip,
html.pd-glass .pd-toggle, html.pd-glass .study-error, html.pd-glass .flash, html.pd-glass .notice, html.pd-glass .pd-section-head, html.pd-glass .pd-steps li,
html.pd-glass .download-separate, html.pd-glass .study-nav-select select, html.pd-glass input:not([type="checkbox"]):not([type="radio"]), html.pd-glass select, html.pd-glass textarea {
  background: var(--g-surface); border: 1px solid var(--g-line); box-shadow: inset 0 1px 0 var(--g-edge), var(--g-shadow);
  -webkit-backdrop-filter: blur(var(--g-blur)) saturate(1.7); backdrop-filter: blur(var(--g-blur)) saturate(1.7); }
html.pd-glass .pd-subject, html.pd-glass .tp-tile, html.pd-glass .pd-toolcard, html.pd-glass .card, html.pd-glass .practice, html.pd-glass .pd-result,
html.pd-glass .topic-node, html.pd-glass .account-prompt, html.pd-glass .study-options-side, html.pd-glass .pd-steps li { border-radius: 18px; }
html.pd-glass .pd-stats, html.pd-glass .pd-pillars { border-radius: 22px; overflow: hidden; }
html.pd-glass .pd-stats { border-top: 1px solid var(--g-line); margin-top: 8px; }
html.pd-glass .pd-stat + .pd-stat, html.pd-glass .pd-pillar + .pd-pillar { border-color: var(--g-line); }
html.pd-glass .pd-pillars { border-top: 1px solid var(--g-line); }
html.pd-glass .pd-section-head { padding: 22px 26px; border-radius: 18px; }
html.pd-glass .pd-steps li { padding: 22px 24px; }

/* Subject tiles keep their colour: a tinted glow instead of a flat coloured top edge. */
html.pd-glass .pd-subject { border-top: 1px solid var(--g-line);
  background: linear-gradient(160deg, color-mix(in srgb, var(--subject, var(--pd-cobalt)) 14%, transparent), transparent 55%), var(--g-surface); }
html.pd-glass .tp-tile { border-left: 1px solid var(--g-line);
  background: linear-gradient(90deg, color-mix(in srgb, var(--subject, var(--pd-cobalt)) 16%, transparent), transparent 42%), var(--g-surface); }
html.pd-glass .pd-result { border-left: 1px solid var(--g-line);
  background: linear-gradient(90deg, color-mix(in srgb, var(--subject, var(--pd-cobalt)) 14%, transparent), transparent 36%), var(--g-surface); }
html.pd-glass .pd-subject-icon, html.pd-glass .pd-toolcard-icon, html.pd-glass .pd-continue-icon { box-shadow: inset 0 1px 0 var(--g-edge), 0 6px 14px -8px rgba(20,35,58,.35); }

/* Hover: lift, brighten, sheen. Pointer-driven tilt and spotlight come from the script (--rx, --ry, --mx, --my). */
html.pd-glass .pd-subject, html.pd-glass .tp-tile, html.pd-glass .pd-toolcard, html.pd-glass .pd-result { position: relative; overflow: hidden; transform-style: preserve-3d;
  transition: transform .18s ease, box-shadow .25s ease, background-color .25s ease, border-color .25s ease; }
html.pd-glass .pd-subject::after, html.pd-glass .tp-tile::after, html.pd-glass .pd-toolcard::after, html.pd-glass .pd-result::after { content: ""; position: absolute; inset: 0; pointer-events: none; z-index: 0;
  background: radial-gradient(280px circle at var(--mx, 50%) var(--my, 0%), color-mix(in srgb, #FFFFFF 45%, transparent), transparent 60%); opacity: 0; transition: opacity .3s ease; }
html.pd-glass .pd-subject > *, html.pd-glass .tp-tile > *, html.pd-glass .pd-toolcard > *, html.pd-glass .pd-result > * { position: relative; z-index: 1; }
@media (hover: hover) {
  html.pd-glass .pd-subject:hover, html.pd-glass .tp-tile:hover, html.pd-glass .pd-toolcard:hover, html.pd-glass .pd-result:hover {
    transform: perspective(900px) rotateX(var(--rx, 0deg)) rotateY(var(--ry, 0deg)) translateY(-4px) scale(1.012); box-shadow: inset 0 1px 0 var(--g-edge), var(--g-shadow-lift);
    background-color: var(--g-surface-strong); border-color: color-mix(in srgb, var(--subject, var(--pd-cobalt)) 45%, var(--g-line)); }
  html.pd-glass .pd-subject:hover::after, html.pd-glass .tp-tile:hover::after, html.pd-glass .pd-toolcard:hover::after, html.pd-glass .pd-result:hover::after { opacity: 1; }
}
html.pd-glass .pd-subject:active, html.pd-glass .tp-tile:active, html.pd-glass .pd-toolcard:active, html.pd-glass .pd-result:active { transform: scale(.985); transition-duration: .08s; }

/* ---------- top bar: frosted, sticky on larger screens ---------- */
html.pd-glass .topbar { border: 0; border-bottom: 1px solid var(--g-line); box-shadow: inset 0 -1px 0 var(--g-edge); transition: box-shadow .3s ease, background-color .3s ease; }
@media (min-width: 601px) { html.pd-glass .topbar { position: sticky; top: 0; z-index: 50; } }
html.pd-glass .topbar.is-scrolled { background: var(--g-surface-strong); box-shadow: inset 0 -1px 0 var(--g-edge), 0 8px 30px -18px rgba(20,35,58,.45); }
html.pd-glass .pd-search-link, html.pd-glass .pd-theme { border-radius: 99px; }
html.pd-glass .pd-theme { background: var(--g-surface); }
html.pd-glass .topbar nav .btn-small { box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--pd-cobalt) 70%, transparent); }

/* ---------- buttons, chips, inputs ---------- */
html.pd-glass .btn { border-radius: 12px; position: relative; overflow: hidden; border-color: transparent;
  background: linear-gradient(180deg, color-mix(in srgb, var(--pd-cobalt) 88%, #FFFFFF), var(--pd-cobalt));
  box-shadow: inset 0 1px 0 rgba(255,255,255,.28), 0 8px 20px -10px color-mix(in srgb, var(--pd-cobalt) 80%, transparent); }
html.pd-glass .btn:hover { background: linear-gradient(180deg, var(--pd-cobalt), var(--pd-cobalt-strong)); box-shadow: inset 0 1px 0 rgba(255,255,255,.28), 0 12px 26px -10px color-mix(in srgb, var(--pd-cobalt) 90%, transparent); }
html.pd-glass .btn-ghost, html.pd-glass .btn.btn-ghost { background: var(--g-surface); color: var(--pd-ink); border: 1px solid var(--g-line);
  box-shadow: inset 0 1px 0 var(--g-edge), var(--g-shadow); -webkit-backdrop-filter: blur(var(--g-blur)); backdrop-filter: blur(var(--g-blur)); }
html.pd-glass .btn-ghost:hover, html.pd-glass .btn.btn-ghost:hover { background: var(--g-surface-strong); color: var(--pd-cobalt); border-color: color-mix(in srgb, var(--pd-cobalt) 40%, var(--g-line)); }
html.pd-glass .btn-small { border-radius: 99px; }
html.pd-glass .pd-chip { border-radius: 99px; border-color: var(--g-line); }
html.pd-glass .pd-chip[aria-pressed="true"] { background: var(--pd-ink); border-color: var(--pd-ink); box-shadow: inset 0 1px 0 rgba(255,255,255,.18), 0 8px 18px -10px rgba(20,35,58,.6); }
html.pd-glass input:not([type="checkbox"]):not([type="radio"]), html.pd-glass select, html.pd-glass textarea { border-radius: 12px; }
html.pd-glass input:focus-visible, html.pd-glass select:focus-visible, html.pd-glass textarea:focus-visible { outline: 0; border-color: color-mix(in srgb, var(--pd-cobalt) 60%, transparent);
  box-shadow: inset 0 1px 0 var(--g-edge), 0 0 0 4px color-mix(in srgb, var(--pd-cobalt) 18%, transparent), var(--g-shadow); }
html.pd-glass .pd-study { background: color-mix(in srgb, var(--subject, var(--pd-cobalt)) 12%, transparent); box-shadow: inset 0 1px 0 var(--g-edge); }
html.pd-glass .pd-board-bar { background: color-mix(in srgb, var(--pd-ink) 8%, transparent); }

/* Ripple (added by the script on press) */
html.pd-glass .pd-ripple { position: absolute; left: var(--x); top: var(--y); width: 12px; height: 12px; margin: -6px 0 0 -6px; border-radius: 50%; pointer-events: none; z-index: 2;
  background: color-mix(in srgb, currentColor 22%, transparent); transform: scale(0); opacity: .9; animation: pd-ripple .55s ease-out forwards; }
@keyframes pd-ripple { to { transform: scale(var(--s, 30)); opacity: 0; } }
html.pd-glass .rating-button, html.pd-glass .pd-toggle button, html.pd-glass .study-controls .btn, html.pd-glass .pd-chip, html.pd-glass .topic-btn { position: relative; overflow: hidden; }

/* ---------- segmented controls: a thumb that slides to the chosen option ---------- */
html.pd-glass .pd-toggle { position: relative; border-radius: 99px; padding: 4px; background: color-mix(in srgb, var(--pd-ink) 7%, transparent); box-shadow: inset 0 1px 2px rgba(20,35,58,.12); border: 1px solid var(--g-line); }
html.pd-glass .pd-toggle .pd-thumb { position: absolute; top: 4px; left: 0; height: calc(100% - 8px); width: 0; border-radius: 99px; z-index: 0; pointer-events: none;
  background: var(--pd-ink); box-shadow: inset 0 1px 0 rgba(255,255,255,.18), 0 4px 12px -4px rgba(20,35,58,.5);
  transition: transform .4s cubic-bezier(.25,1.35,.4,1), width .4s cubic-bezier(.25,1.35,.4,1); }
html.pd-glass[data-theme="dark"] .pd-toggle .pd-thumb { background: #E9A23B; }
@media (prefers-color-scheme: dark) { html.pd-glass:not([data-theme="light"]) .pd-toggle .pd-thumb { background: #E9A23B; } }
html.pd-glass .pd-toggle button { position: relative; z-index: 1; transition: color .25s ease; }
html.pd-glass .pd-toggle:has(.pd-thumb) button[aria-pressed="true"] { background: transparent; box-shadow: none; }
html.pd-glass .pd-toggle:has(.pd-thumb) button:hover:not([aria-pressed="true"]):not(:disabled) { background: color-mix(in srgb, var(--pd-ink) 6%, transparent); }

/* ---------- study page ---------- */
html.pd-glass .study-nav { padding: 12px; }
html.pd-glass .topic-btn { border-radius: 12px; background: var(--g-surface); border: 1px solid var(--g-line); border-left: 4px solid var(--subject, var(--pd-cobalt)); box-shadow: inset 0 1px 0 var(--g-edge); }
html.pd-glass .topic-btn.active { background: var(--subject, var(--pd-cobalt)); border-color: var(--subject, var(--pd-cobalt)); box-shadow: inset 0 1px 0 rgba(255,255,255,.2), 0 8px 18px -10px color-mix(in srgb, var(--subject, var(--pd-cobalt)) 80%, transparent); }
html.pd-glass .rating-button { border-radius: 14px; border: 1px solid color-mix(in srgb, currentColor 30%, transparent); background: var(--g-surface); box-shadow: inset 0 1px 0 var(--g-edge), var(--g-shadow);
  -webkit-backdrop-filter: blur(var(--g-blur)); backdrop-filter: blur(var(--g-blur)); }
html.pd-glass .rating-1 { background: linear-gradient(180deg, color-mix(in srgb, #9e343c 14%, transparent), transparent), var(--g-surface); }
html.pd-glass .rating-2 { background: linear-gradient(180deg, color-mix(in srgb, #805a12 14%, transparent), transparent), var(--g-surface); }
html.pd-glass .rating-3 { background: linear-gradient(180deg, color-mix(in srgb, #216952 14%, transparent), transparent), var(--g-surface); }
html.pd-glass .rating-4 { background: linear-gradient(180deg, color-mix(in srgb, #285b96 14%, transparent), transparent), var(--g-surface); }
html.pd-glass .rating-button:hover:not(:disabled) { box-shadow: inset 0 1px 0 var(--g-edge), 0 0 0 1px currentColor, var(--g-shadow-lift); }
html.pd-glass .frame-stack iframe { border-radius: 16px; }
html.pd-glass .practice-option { border-radius: 12px; background: var(--g-surface); border: 1px solid var(--g-line); box-shadow: inset 0 1px 0 var(--g-edge); }
html.pd-glass .study-more summary { border-radius: 99px; }
@media (max-width: 600px) {
  /* Floating glass bar at the bottom, like an iOS tab bar. */
  html.pd-glass .study-controls, html.pd-glass #study-ratings:not([hidden]) { margin: 6px 8px 0; padding: 10px 10px calc(10px + env(safe-area-inset-bottom)); bottom: 8px; border-radius: 22px;
    background: var(--g-surface-strong); border: 1px solid var(--g-line); box-shadow: inset 0 1px 0 var(--g-edge), 0 14px 36px -12px rgba(20,35,58,.45);
    -webkit-backdrop-filter: blur(22px) saturate(1.8); backdrop-filter: blur(22px) saturate(1.8); }
  html.pd-glass .study-main:has(#study-ratings:not([hidden])) .study-controls { background: none; border: 0; box-shadow: none; }
  html.pd-glass .study-controls .btn { border-radius: 14px; }
}
html.pd-glass .study-top { background: transparent; }
@media (min-width: 901px) { html.pd-glass .study-page .study-top { background: var(--g-surface); -webkit-backdrop-filter: blur(var(--g-blur)); backdrop-filter: blur(var(--g-blur)); border-radius: 0 0 16px 16px; padding-left: 16px; padding-right: 16px; margin-left: -16px; margin-right: -16px; box-shadow: inset 0 -1px 0 var(--g-edge); } }

/* ---------- home ---------- */
html.pd-glass .pd-hero-copy h1 i { background: linear-gradient(100deg, var(--pd-cobalt), var(--pd-cobalt-strong)); -webkit-background-clip: text; background-clip: text; color: transparent; }
html.pd-glass .pd-chart { border-radius: 22px; }
html.pd-glass .pd-stat strong { background: linear-gradient(180deg, var(--pd-ink), color-mix(in srgb, var(--pd-ink) 70%, var(--pd-cobalt))); -webkit-background-clip: text; background-clip: text; color: transparent; }
html.pd-glass .pd-footer { border-radius: 28px 28px 0 0; }

/* ---------- tools page filter row on phones keeps its fade mask; chips are glass ---------- */
html.pd-glass .pd-filter { padding-top: 4px; }