/* AI Scientific Animation Showcase V2 — styles
   Palette: warm paper, moss green and copper; topic A blue, topic B rust (same as the videos). */
:root {
  --bg: #f3eed8;
  --bg2: #ece5cc;
  --paper: #fffdf7;
  --ink: #1f2a24;
  --ink2: #46554d;
  --ink3: #6d7a72;
  --line: #ddd4bf;
  --moss: #254d3a;
  --mossL: #e3ece5;
  --copper: #8b6914;
  --copperL: #f4ead0;
  --A: #1f5f8b;
  --B: #b4532a;
  --shadow: 0 1px 2px rgba(31, 42, 36, 0.05), 0 12px 32px rgba(31, 42, 36, 0.08);
  --shadow-hi: 0 2px 4px rgba(31, 42, 36, 0.06), 0 22px 48px rgba(31, 42, 36, 0.14);
  --serif: Cambria, Georgia, 'Noto Serif TC', 'PMingLiU', serif;
  --sans: 'Segoe UI', system-ui, -apple-system, 'Microsoft JhengHei', 'PingFang TC', 'Noto Sans TC', 'Helvetica Neue', Arial, sans-serif;
  --mono: Consolas, ui-monospace, 'SFMono-Regular', Menlo, 'Microsoft JhengHei', monospace;
  --r: 18px;
  --max: 1240px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 76px; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.7 var(--sans); -webkit-font-smoothing: antialiased; }
html:lang(en) body { line-height: 1.6; }
img { max-width: 100%; display: block; }
a { color: var(--moss); }
h1, h2, h3 { font-family: var(--serif); font-weight: 700; line-height: 1.2; margin: 0; letter-spacing: -0.005em; }
html:lang(zh-Hant-TW) h1, html:lang(zh-Hant-TW) h2, html:lang(zh-Hant-TW) h3 { font-family: var(--sans); letter-spacing: 0.01em; }
sub, sup { font-size: 0.68em; line-height: 0; }
.wrap { max-width: var(--max); margin: 0 auto; padding: 0 24px; }
.eyebrow { font: 700 13px/1.3 var(--sans); letter-spacing: 0.16em; text-transform: uppercase; color: var(--copper); margin: 0 0 14px; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 12px 22px; border-radius: 999px; border: 1.5px solid var(--moss); background: transparent; color: var(--moss); font: 600 15px/1 var(--sans); text-decoration: none; cursor: pointer; transition: background 0.15s, color 0.15s, transform 0.15s; }
.btn:hover { background: var(--mossL); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--moss); color: #fff; }
.btn.primary:hover { background: #1b3b2c; }
.btn.small { padding: 9px 16px; font-size: 14px; }
.btn.copied { background: var(--copper); border-color: var(--copper); color: #fff; }
.btn:focus-visible, button:focus-visible, summary:focus-visible, a:focus-visible, pre:focus-visible { outline: 3px solid var(--copper); outline-offset: 2px; }

/* ------------------------------------------------------------ top navigation (sticky) */
.topnav { position: sticky; top: 0; z-index: 30; background: rgba(243, 238, 216, 0.9); backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.topnav .wrap { display: flex; align-items: center; gap: 20px; height: 60px; }
.brand { font: 700 16px/1 var(--sans); color: var(--ink); text-decoration: none; white-space: nowrap; display: flex; align-items: center; gap: 10px; }
.brand .mark { width: 26px; height: 26px; border-radius: 8px; background: linear-gradient(135deg, var(--moss), var(--copper)); display: grid; place-items: center; color: #fff; font: 700 13px/1 var(--sans); }
.navlinks { display: flex; gap: 2px; margin-left: auto; overflow-x: auto; scrollbar-width: none; }
.navlinks::-webkit-scrollbar { display: none; }
.navlinks a { padding: 8px 12px; border-radius: 999px; color: var(--ink2); text-decoration: none; font: 600 14px/1 var(--sans); white-space: nowrap; }
.navlinks a:hover { background: var(--paper); color: var(--ink); }
.navlinks a.active { background: var(--moss); color: #fff; }
.lang { display: flex; align-items: center; gap: 2px; flex-shrink: 0; color: var(--ink3); font-size: 14px; }
.lang button { border: 0; background: transparent; padding: 7px 8px; border-radius: 8px; font: 600 14px/1 var(--sans); color: var(--ink3); cursor: pointer; }
.lang button:hover { color: var(--ink); background: var(--paper); }
.lang button[aria-pressed='true'] { color: var(--moss); text-decoration: underline; text-decoration-thickness: 2px; text-underline-offset: 5px; }

/* ------------------------------------------------------------ 01 hero */
.hero { padding: 72px 0 64px; background: radial-gradient(1200px 520px at 70% 0%, #fbf8ec 0%, rgba(251, 248, 236, 0) 70%); }
.hero-grid { display: grid; grid-template-columns: 1.05fr 1fr; gap: 48px; align-items: center; }
.hero h1 { font-size: clamp(36px, 4.6vw, 58px); }
.hero .lede { font-size: clamp(18px, 1.8vw, 21px); color: var(--ink2); margin: 18px 0 22px; max-width: 600px; }
ul.notes { list-style: none; padding: 0; margin: 0 0 30px; display: grid; gap: 10px; max-width: 600px; }
ul.notes li { position: relative; padding-left: 30px; color: var(--ink); font-size: 16px; }
ul.notes li::before { content: ''; position: absolute; left: 0; top: 0.5em; width: 18px; height: 18px; border-radius: 50%; background: var(--mossL) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23254d3a' stroke-width='3'%3E%3Cpath d='M6 12l4 4 8-9'/%3E%3C/svg%3E") center / 12px no-repeat; transform: translateY(-2px); }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; }
.mosaic { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; transform: rotate(-1.2deg); }
.mosaic button { position: relative; padding: 0; border: 0; border-radius: 10px; overflow: hidden; cursor: pointer; aspect-ratio: 16 / 9; background: var(--bg2); box-shadow: var(--shadow); transition: transform 0.2s, box-shadow 0.2s; }
.mosaic button:hover { transform: translateY(-3px) scale(1.04); box-shadow: var(--shadow-hi); z-index: 2; }
.mosaic img { width: 100%; height: 100%; object-fit: cover; }
.mosaic .lbl { position: absolute; left: 6px; bottom: 6px; padding: 2px 6px; border-radius: 6px; font: 700 11px/1.2 var(--sans); color: #fff; }
.lbl.A, .tag.A { background: var(--A); }
.lbl.B, .tag.B { background: var(--B); }
.tag { display: inline-flex; align-items: center; justify-content: center; min-width: 46px; height: 28px; padding: 0 10px; border-radius: 8px; color: #fff; font: 700 13px/1 var(--sans); letter-spacing: 0.04em; }

/* ------------------------------------------------------------ sections */
section.block { padding: 72px 0; }
section.block.alt { background: var(--paper); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section-head { max-width: 820px; margin-bottom: 36px; }
.section-head h2 { font-size: clamp(28px, 3.2vw, 40px); }
.section-head p { color: var(--ink2); margin: 14px 0 0; }

/* ------------------------------------------------------------ 02 videos */
.topic + .topic { margin-top: 64px; }
.topic-head { margin-bottom: 26px; max-width: 900px; }
.topic-head .cat { font: 700 13px/1.3 var(--sans); letter-spacing: 0.1em; margin: 0 0 10px; }
.topic[data-topic='A'] .cat { color: var(--A); }
.topic[data-topic='B'] .cat { color: var(--B); }
.topic-head h3 { font-size: clamp(24px, 2.6vw, 32px); display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.topic-head p { margin: 10px 0 0; color: var(--ink2); }
.cards { display: grid; grid-template-columns: repeat(5, 1fr); gap: 18px; }
.card { display: flex; flex-direction: column; border-radius: var(--r); background: var(--paper); border: 1px solid var(--line); box-shadow: var(--shadow); overflow: hidden; transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s; }
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hi); }
.topic[data-topic='A'] .card:hover { border-color: #b7cde0; }
.topic[data-topic='B'] .card:hover { border-color: #e2bba8; }
.thumb { position: relative; display: block; width: 100%; padding: 0; border: 0; cursor: pointer; aspect-ratio: 16 / 9; background: var(--bg2); overflow: hidden; }
.thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.35s; }
.card:hover .thumb img { transform: scale(1.04); }
.thumb .play { position: absolute; inset: 0; margin: auto; width: 52px; height: 52px; border-radius: 50%; background: rgba(255, 253, 247, 0.92); display: grid; place-items: center; box-shadow: 0 8px 24px rgba(0, 0, 0, 0.18); transition: transform 0.2s; }
.thumb:hover .play { transform: scale(1.1); }
.thumb .play svg { margin-left: 3px; }
.thumb .dur, .thumb .ver { position: absolute; bottom: 8px; padding: 2px 7px; border-radius: 6px; font: 700 11.5px/1.3 var(--sans); color: #fff; background: rgba(20, 28, 24, 0.78); }
.thumb .dur { right: 8px; }
.thumb .ver { left: 8px; }
.topic[data-topic='A'] .thumb .ver { background: var(--A); }
.topic[data-topic='B'] .thumb .ver { background: var(--B); }
.thumb .pending { position: absolute; inset: 0; display: grid; place-items: center; font: 600 14px/1.3 var(--sans); color: var(--ink2); background: repeating-linear-gradient(135deg, var(--bg2) 0 12px, var(--bg) 12px 24px); }
.card .body { display: flex; flex-direction: column; gap: 8px; padding: 16px 16px 16px; flex: 1; }
.card h4 { margin: 0; font: 700 18px/1.3 var(--sans); }
.card .en { margin: -4px 0 0; font-size: 13px; color: var(--ink3); }
.card .style { align-self: flex-start; padding: 3px 10px; border-radius: 999px; background: var(--bg); border: 1px solid var(--line); font-size: 12.5px; font-weight: 600; color: var(--ink2); }
.card .desc { margin: 0; font-size: 14.5px; line-height: 1.65; color: var(--ink2); flex: 1; }
/* style keywords: reusable descriptors a visitor copies into the prompt's "style reference" field */
.kw { display: flex; flex-wrap: wrap; gap: 5px; }
.kw span { padding: 2px 8px; border-radius: 6px; background: var(--copperL); border: 1px solid #e6d6ab; font-size: 12px; line-height: 1.5; color: #5b4510; }
.kw-copy { align-self: flex-start; margin-top: 2px; padding: 6px 12px; border-radius: 999px; border: 1.5px solid var(--copper); background: transparent; color: var(--copper); font: 700 12.5px/1.2 var(--sans); cursor: pointer; transition: background 0.15s, color 0.15s; }
.kw-copy:hover { background: var(--copperL); }
.kw-copy.copied { background: var(--copper); color: #fff; }

/* ------------------------------------------------------------ 03 why */
.uses { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.use { padding: 24px 22px; border-radius: var(--r); background: var(--bg); border: 1px solid var(--line); display: flex; flex-direction: column; gap: 10px; }
.use .ic { width: 42px; height: 42px; border-radius: 12px; display: grid; place-items: center; background: var(--paper); border: 1px solid var(--line); }
.use h3 { font-size: 19px; }
.use p { margin: 0; font-size: 15px; color: var(--ink2); flex: 1; }
.use .ex { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; font-size: 13px; color: var(--ink3); }
.use .ex button { border: 0; padding: 4px 9px; border-radius: 7px; color: #fff; font: 700 12px/1.2 var(--sans); cursor: pointer; }
.use .ex button.A { background: var(--A); }
.use .ex button.B { background: var(--B); }
.use .ex button:hover { filter: brightness(1.12); }

/* ------------------------------------------------------------ 04 prompt */
.prompt-grid { display: grid; grid-template-columns: 1.55fr 1fr; gap: 26px; align-items: start; }
.prompt-main { min-width: 0; }
.ver { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px; margin-bottom: 14px; }
.ver-toggle { display: inline-flex; padding: 4px; border-radius: 999px; background: var(--paper); border: 1px solid var(--line); }
.ver-toggle button { border: 0; background: transparent; padding: 10px 18px; border-radius: 999px; font: 700 15px/1 var(--sans); color: var(--ink2); cursor: pointer; }
.ver-toggle button:hover { color: var(--ink); }
.ver-toggle button[aria-checked='true'] { background: var(--moss); color: #fff; }
.ver-desc { margin: 0; flex: 1; min-width: 240px; font-size: 15px; color: var(--ink2); }
.prompt-card { border-radius: var(--r); background: #1d2721; box-shadow: var(--shadow-hi); overflow: hidden; }
.prompt-bar { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between; padding: 14px 16px 14px 22px; border-bottom: 1px solid #33423a; }
.prompt-name { font: 700 14px/1.3 var(--sans); letter-spacing: 0.06em; color: #d9d2bd; }
.prompt-actions { display: flex; gap: 10px; align-items: center; }
.prompt-card .btn.small { border-color: #6f8f7d; color: #dfe6e1; }
.prompt-card .btn.small:hover { background: #26352d; }
.prompt-card .btn.primary { background: #e9c46a; border-color: #e9c46a; color: #1d2721; }
.prompt-card .btn.primary:hover { background: #f1d389; }
.prompt-card .btn.copied { background: #9fd3b0; border-color: #9fd3b0; color: #1d2721; }
pre.prompt { margin: 0; max-height: 620px; overflow: auto; padding: 20px 24px 26px; color: #ece6d4; font: 14px/1.75 var(--mono); white-space: pre-wrap; word-break: break-word; }
pre.prompt mark { background: rgba(233, 196, 106, 0.18); color: #f3d98f; border-radius: 4px; padding: 0 2px; }
.prompt-side { display: grid; gap: 20px; }
.prompt-side h3 { font-size: 19px; margin-bottom: 10px; }
ol.how { margin: 0; padding-left: 22px; display: grid; gap: 10px; color: var(--ink2); font-size: 15.5px; }
ol.how b { color: var(--ink); }
.note { padding: 20px 22px; border-radius: var(--r); background: var(--copperL); border: 1px solid #e3d3a6; }
.note p { margin: 0; font-size: 15px; color: var(--ink); }
.note.first { background: var(--paper); border-color: var(--line); }
.note.first p { color: var(--ink2); margin-bottom: 8px; }
.note.first ul { margin: 0; padding-left: 20px; display: grid; gap: 6px; font-size: 14.5px; color: var(--ink2); }
.note.first b { color: var(--ink); }

/* ------------------------------------------------------------ 05 guide */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-bottom: 22px; }
.step { padding: 22px 22px 24px; border-radius: var(--r); background: var(--bg); border: 1px solid var(--line); }
.step .n { width: 34px; height: 34px; border-radius: 50%; background: var(--moss); color: #fff; display: grid; place-items: center; font: 700 15px/1 var(--sans); margin-bottom: 12px; }
.step h3 { font-size: 19px; margin-bottom: 6px; }
.step p { margin: 0; font-size: 15px; color: var(--ink2); }
details.adv { border-radius: var(--r); border: 1px solid var(--line); background: var(--bg); padding: 16px 22px; }
details.adv summary { cursor: pointer; font-weight: 700; color: var(--moss); }
details.adv div { margin-top: 12px; color: var(--ink2); font-size: 15px; }
details.adv div p { margin: 0 0 10px; }
details.adv code { font-family: var(--mono); font-size: 0.92em; background: var(--paper); border: 1px solid var(--line); border-radius: 5px; padding: 1px 5px; }

/* ------------------------------------------------------------ footer */
footer { padding: 36px 0 52px; color: var(--ink3); font-size: 14px; }
footer .wrap { display: flex; flex-wrap: wrap; gap: 10px 28px; justify-content: space-between; }
footer p { margin: 0; }

/* ------------------------------------------------------------ player */
dialog.player { width: min(1180px, 94vw); max-height: 94vh; padding: 0; border: 0; border-radius: 20px; background: #121a16; color: #ece6d4; box-shadow: 0 30px 90px rgba(0, 0, 0, 0.45); overflow: auto; }
dialog.player::backdrop { background: rgba(14, 20, 17, 0.72); backdrop-filter: blur(3px); }
.player video { width: 100%; display: block; aspect-ratio: 16 / 9; background: #000; }
.player .info { padding: 18px 24px 22px; }
.player h3 { color: #fff; font: 700 22px/1.3 var(--sans); }
.player .sub { color: #b9c2bc; margin: 6px 0 0; font-size: 15px; }
.player-kw { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; margin-top: 14px; }
.player-kw .kw span { background: #1b2620; border-color: #36443d; color: #e7dcb8; font-size: 13px; }
.player-kw .kw-copy { margin: 0; border-color: #e9c46a; color: #e9c46a; }
.player-kw .kw-copy:hover { background: #26352d; }
.player-kw .kw-copy.copied { background: #e9c46a; color: #121a16; }
.player .close { position: sticky; top: 10px; float: right; margin: 10px 10px -52px 0; z-index: 2; width: 42px; height: 42px; border-radius: 50%; border: 0; background: rgba(255, 255, 255, 0.92); color: #121a16; font-size: 22px; cursor: pointer; }

.toast { position: fixed; left: 50%; bottom: 26px; transform: translateX(-50%) translateY(20px); padding: 12px 20px; border-radius: 999px; background: var(--ink); color: #fff; font: 600 14px/1.2 var(--sans); opacity: 0; pointer-events: none; transition: opacity 0.2s, transform 0.2s; z-index: 60; }
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ------------------------------------------------------------ responsive */
@media (max-width: 1180px) {
  .cards { grid-template-columns: repeat(3, 1fr); }
  .uses { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 900px) {
  .hero-grid, .prompt-grid { grid-template-columns: 1fr; }
  .mosaic { transform: none; }
  .cards { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: 1fr; }
  .topnav .brand .full { display: none; }
}
@media (max-width: 600px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px; }
  .topnav .wrap { gap: 10px; }
  .navlinks { display: none; }
  .lang { margin-left: auto; }
  .hero { padding: 40px 0 48px; }
  section.block { padding: 52px 0; }
  .cards, .uses { grid-template-columns: 1fr; }
  .mosaic { gap: 5px; }
  pre.prompt { font-size: 13px; padding: 16px 16px 20px; }
  .prompt-bar { padding: 12px 14px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}