/* ================= AI 学院 · 明亮温馨多彩设计系统 ================= */
:root {
  --bg: #fffaf3; --bg2: #fff3e6; --panel: #ffffff; --panel2: #fffdf9;
  --line: #f0e6da; --line2: #e6d8c8;
  --tx: #2b2a3a; --dim: #6b6880; --mute: #9b97ab;
  /* 主色（名字沿用，色值换成明亮温暖的） */
  --cy: #12b5cb; --mg: #f7577f; --yl: #f5a000; --gr: #20b97a; --pp: #7d5cf5; --rd: #ef4848; --or: #ff8a3d; --bl: #3d8bfd;
  --c: var(--cy);
  --font: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", "Source Han Sans SC", system-ui, sans-serif;
  --mono: "SF Mono", "JetBrains Mono", "Cascadia Code", Consolas, monospace;
  --r: 20px; --r-sm: 12px;
  --shadow: 0 6px 24px rgba(160, 110, 60, .10), 0 1px 3px rgba(160, 110, 60, .08);
  --shadow-lg: 0 18px 50px rgba(160, 110, 60, .16);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--tx); font-family: var(--font); font-size: 16px; line-height: 1.8;
  background-image:
    radial-gradient(700px 420px at 92% -5%, rgba(255, 196, 120, .30), transparent 70%),
    radial-gradient(640px 460px at -8% 18%, rgba(130, 214, 255, .22), transparent 70%),
    radial-gradient(600px 500px at 50% 110%, rgba(255, 170, 200, .18), transparent 70%),
    radial-gradient(#f3e3d0 1.2px, transparent 1.2px);
  background-size: auto, auto, auto, 26px 26px;
  background-attachment: fixed;
  min-height: 100vh; overflow-x: hidden;
}
a { color: var(--bl); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
::selection { background: #ffe08a; color: var(--tx); }
h1, h2, h3, h4 { line-height: 1.3; margin: 0 0 .5em; letter-spacing: .01em; }
.mono { font-family: var(--mono); }
.dim { color: var(--dim); }
.wrap { max-width: 1240px; margin: 0 auto; padding: 0 24px; }
.hidden { display: none !important; }

/* 章节颜色 */
.c-cyan { --c: var(--cy); --cbg: #e3f8fb; } .c-blue { --c: var(--bl); --cbg: #e6f0ff; } .c-green { --c: var(--gr); --cbg: #e2f7ee; }
.c-yellow { --c: var(--yl); --cbg: #fff3d6; } .c-orange { --c: var(--or); --cbg: #ffecdf; } .c-red { --c: var(--rd); --cbg: #fde7e7; }
.c-purple { --c: var(--pp); --cbg: #efeaff; } .c-magenta { --c: var(--mg); --cbg: #ffe7ee; }

/* ---------- 导航 ---------- */
.nav { position: sticky; top: 0; z-index: 50; backdrop-filter: blur(14px); background: rgba(255, 250, 243, .85); border-bottom: 1px solid var(--line); }
.nav .wrap { display: flex; align-items: center; gap: 28px; height: 66px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--tx); font-weight: 800; letter-spacing: .03em; white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand .logo { width: 36px; height: 36px; border-radius: 12px; display: grid; place-items: center; background: conic-gradient(from 200deg, #ff8a3d, #f7577f, #7d5cf5, #3d8bfd, #12b5cb, #20b97a, #f5a000, #ff8a3d); box-shadow: 0 4px 12px rgba(247, 87, 127, .3); }
.brand .logo i { width: 14px; height: 14px; border-radius: 50%; background: #fff; }
.brand small { display: block; font-size: 10px; color: var(--mute); letter-spacing: .25em; font-weight: 500; line-height: 1; }
.nav-links { display: flex; gap: 4px; flex: 1; }
.nav-links a { color: var(--dim); padding: 7px 14px; font-size: 15px; border-radius: 999px; font-weight: 600; }
.nav-links a:hover { color: var(--tx); background: #fff; text-decoration: none; }
.nav-links a.on { color: #fff; background: var(--tx); }
.nav-user { display: flex; gap: 10px; align-items: center; font-size: 14px; }
.nav-toggle { display: none; background: #fff; border: 1px solid var(--line2); color: var(--tx); width: 42px; height: 38px; font-size: 18px; border-radius: 10px; }
@media (max-width: 860px) {
  .nav-links { display: none; position: absolute; top: 66px; left: 0; right: 0; flex-direction: column; background: var(--bg); padding: 12px 24px; border-bottom: 1px solid var(--line); }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; margin-left: auto; }
  .nav-user .uname { display: none; }
}

/* ---------- 按钮 ---------- */
.btn {
  --bc: var(--tx); display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 11px 24px; border: 0; cursor: pointer; font: 700 15px var(--font); letter-spacing: .02em;
  color: #fff; background: var(--bc); border-radius: 999px; text-decoration: none; white-space: nowrap;
  box-shadow: 0 4px 14px color-mix(in srgb, var(--bc) 30%, transparent);
  transition: transform .15s, box-shadow .15s, filter .15s;
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 8px 22px color-mix(in srgb, var(--bc) 38%, transparent); text-decoration: none; filter: brightness(1.05); }
.btn:active { transform: translateY(0); }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.btn.ghost { background: #fff; color: var(--bc); box-shadow: inset 0 0 0 2px color-mix(in srgb, var(--bc) 35%, transparent); }
.btn.ghost:hover { box-shadow: inset 0 0 0 2px var(--bc), 0 6px 16px color-mix(in srgb, var(--bc) 18%, transparent); }
.btn.mg { --bc: var(--mg); } .btn.yl { --bc: var(--yl); } .btn.gr { --bc: var(--gr); } .btn.rd { --bc: var(--rd); } .btn.dim { --bc: var(--dim); }
.btn.cy { --bc: var(--cy); } .btn.pp { --bc: var(--pp); } .btn.or { --bc: var(--or); }
.btn.sm { padding: 6px 14px; font-size: 13px; }
.btn.lg { padding: 15px 34px; font-size: 17px; }

/* ---------- 面板 / 卡片 ---------- */
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: var(--r); box-shadow: var(--shadow); position: relative; }
.card { padding: 26px; }
.tag { display: inline-block; font-size: 12px; font-weight: 700; padding: 3px 12px; border-radius: 999px; color: var(--c); background: var(--cbg, #f3f0ff); }
.kicker { font-size: 13px; font-weight: 800; color: var(--c); letter-spacing: .2em; text-transform: uppercase; margin-bottom: 10px; display: inline-flex; align-items: center; gap: 10px; }
.kicker::before { content: ""; width: 10px; height: 10px; border-radius: 50%; background: var(--c); box-shadow: 14px 0 0 color-mix(in srgb, var(--c) 45%, transparent), 28px 0 0 color-mix(in srgb, var(--c) 20%, transparent); margin-right: 30px; }
.section { padding: 90px 0; }
.section-title { font-size: clamp(28px, 4vw, 44px); font-weight: 900; }
.section-title em { font-style: normal; color: var(--c); background: linear-gradient(transparent 62%, color-mix(in srgb, var(--c) 22%, transparent) 62%); padding: 0 4px; }

/* 多彩渐变文字（替代原故障文字） */
.glitch { background: linear-gradient(90deg, #ff8a3d, #f7577f 35%, #7d5cf5 70%, #3d8bfd); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* ---------- 表单 ---------- */
.field { margin-bottom: 16px; }
.field label { display: block; font-size: 13px; color: var(--dim); margin-bottom: 6px; font-weight: 600; }
.input, select.input, textarea.input {
  width: 100%; padding: 11px 14px; background: #fff; color: var(--tx); border: 1.5px solid var(--line2); border-radius: var(--r-sm);
  font: 15px var(--font); outline: none; transition: border-color .15s, box-shadow .15s;
}
textarea.input { min-height: 90px; resize: vertical; line-height: 1.6; }
textarea.code { font: 12.5px/1.5 var(--mono); min-height: 160px; }
.input:focus { border-color: var(--bl); box-shadow: 0 0 0 4px rgba(61, 139, 253, .15); }
.input:disabled { background: #f7f3ee; }
.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.grow { flex: 1; }
.check { display: flex; align-items: flex-start; gap: 10px; padding: 8px 0; cursor: pointer; }
.check input { width: 18px; height: 18px; accent-color: var(--bl); margin-top: 4px; flex: none; }

/* ---------- 提示 ---------- */
#toast { position: fixed; right: 20px; bottom: 20px; z-index: 1000; display: flex; flex-direction: column; gap: 10px; }
.toast { background: #fff; border-left: 5px solid var(--bl); border-radius: 12px; padding: 12px 18px; min-width: 240px; max-width: 380px; box-shadow: var(--shadow-lg); animation: tin .25s; font-size: 14px; }
.toast.err { border-color: var(--rd); } .toast.ok { border-color: var(--gr); }
@keyframes tin { from { transform: translateY(20px); opacity: 0; } }
.notice { padding: 14px 18px; border: 2px dashed var(--line2); color: var(--dim); font-size: 14px; border-radius: var(--r-sm); background: #fff; }

/* ---------- 模态框 ---------- */
.modal-bg { position: fixed; inset: 0; background: rgba(60, 40, 30, .35); z-index: 200; display: grid; place-items: center; padding: 20px; backdrop-filter: blur(6px); }
.modal { width: min(760px, 100%); max-height: 90vh; overflow: auto; padding: 30px; border-top: 6px solid var(--c); }
.modal h3 { color: var(--c); }

/* ---------- 表格 ---------- */
.tbl { width: 100%; border-collapse: collapse; font-size: 14px; background: #fff; border-radius: var(--r-sm); overflow: hidden; }
.tbl th { text-align: left; font-size: 12px; font-weight: 700; color: var(--dim); padding: 12px 10px; border-bottom: 1.5px solid var(--line2); white-space: nowrap; background: #fffaf3; }
.tbl td { padding: 11px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
.tbl tr:hover td { background: #fffaf3; }
.st { font-size: 12px; font-weight: 700; padding: 2px 10px; border-radius: 999px; white-space: nowrap; background: #f3f0ec; }
.st.pending { color: #b97700; background: #fff3d6; } .st.active { color: #12935f; background: #e2f7ee; } .st.rejected, .st.disabled { color: var(--rd); background: #fde7e7; }
.st.owner { color: var(--mg); background: #ffe7ee; } .st.admin { color: var(--bl); background: #e6f0ff; } .st.student { color: var(--dim); }

/* ---------- SVG 插图系统（亮色版） ---------- */
.ill svg { width: 100%; height: auto; display: block; overflow: visible; }
.ill svg :is(rect, circle, path, line, polyline, polygon, ellipse) { fill: none; stroke: #8a8699; stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round; }
.ill svg text { fill: var(--tx); font-family: var(--font); font-size: 14px; stroke: none; font-weight: 600; }
.ill svg .mid { text-anchor: middle; }
.ill svg .t-s { font-size: 12px; font-weight: 500; } .ill svg .t-l { font-size: 19px; font-weight: 800; }
.ill svg .mono { font-family: var(--mono); }
.ill svg .c { stroke: var(--cy); } .ill svg .m { stroke: var(--mg); } .ill svg .y { stroke: var(--yl); } .ill svg .g { stroke: var(--gr); }
.ill svg .p { stroke: var(--pp); } .ill svg .r { stroke: var(--rd); } .ill svg .o { stroke: var(--or); } .ill svg .w { stroke: #a9a4b8; }
.ill svg :is(rect, circle, path, ellipse, text):is(.fc, .fm, .fy, .fg, .fp, .fr, .fo, .fw) { stroke: none; }
.ill svg .fc { fill: var(--cy); } .ill svg .fm { fill: var(--mg); } .ill svg .fy { fill: var(--yl); } .ill svg .fg { fill: var(--gr); }
.ill svg .fp { fill: var(--pp); } .ill svg .fr { fill: var(--rd); } .ill svg .fo { fill: var(--or); } .ill svg .fw { fill: #8a8699; }
.ill svg .bc { fill: #dff7fa; } .ill svg .bm { fill: #ffe6ee; } .ill svg .by { fill: #fff2cc; }
.ill svg .bg { fill: #ddf6ea; } .ill svg .bp { fill: #ece6ff; } .ill svg .br { fill: #fde4e4; } .ill svg .bo { fill: #ffe9da; }
.ill svg .thin { stroke-width: 1.4; } .ill svg .thick { stroke-width: 4.5; }
.ill svg .dots { stroke-width: 7; }
.ill svg .dash { stroke-dasharray: 6 6; }
.ill svg .flow { stroke-dasharray: 8 6; animation: flow 1.2s linear infinite; }
.ill svg .glow { filter: drop-shadow(0 3px 6px rgba(120, 90, 60, .18)); }
.ill svg .pulse { animation: pulse 2s ease-in-out infinite; }
.ill svg .blink { animation: blink 1s steps(1) infinite; }
.ill svg .spin { transform-box: fill-box; transform-origin: center; animation: spin 6s linear infinite; }
.ill svg .cursor { animation: cursor 5s ease-in-out infinite; }
@keyframes flow { to { stroke-dashoffset: -28; } }
@keyframes pulse { 50% { opacity: .4; } }
@keyframes blink { 50% { opacity: 0; } }
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes cursor { 0%, 10% { transform: translate(120px, 70px); } 40%, 50% { transform: translate(200px, 120px); } 75%, 100% { transform: translate(290px, 156px); } }
@keyframes floaty { 50% { transform: translateY(-8px); } }
@media (prefers-reduced-motion: reduce) { .ill svg * { animation: none !important; } }

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--line); padding: 36px 0; color: var(--mute); font-size: 13px; margin-top: 60px; background: #fff7ee; }
.footer .wrap { display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; }

/* ---------- 通用栅格 ---------- */
.grid { display: grid; gap: 20px; }
.g2 { grid-template-columns: repeat(2, 1fr); } .g3 { grid-template-columns: repeat(3, 1fr); } .g4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 960px) { .g3, .g4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 620px) { .g2, .g3, .g4 { grid-template-columns: 1fr; } .wrap { padding: 0 16px; } .section { padding: 60px 0; } }

.loading { padding: 60px; text-align: center; color: var(--dim); font-weight: 700; letter-spacing: .2em; }
.loading::after { content: " ●"; animation: blink 1s steps(1) infinite; color: var(--mg); }

/* ---------- 互动演示 ---------- */
.demo { margin-top: 22px; border-radius: var(--r); background: linear-gradient(135deg, #fffaf0, #fff); border: 2px dashed color-mix(in srgb, var(--c) 40%, transparent); padding: 20px 22px; }
.demo-h { display: flex; align-items: center; gap: 10px; font-weight: 800; color: var(--c); margin-bottom: 12px; }
.demo-h::before { content: "🎮"; }
.demo-h small { color: var(--mute); font-weight: 500; margin-left: auto; font-size: 12px; }
.chip { display: inline-block; padding: 4px 10px; margin: 3px; border-radius: 8px; font-weight: 700; font-size: 15px; transition: transform .2s; }
.bars { display: grid; gap: 6px; }
.bar-row { display: grid; grid-template-columns: 72px 1fr 54px; align-items: center; gap: 10px; font-size: 14px; }
.bar-row .b { height: 18px; border-radius: 9px; background: #f2ece4; overflow: hidden; }
.bar-row .b i { display: block; height: 100%; border-radius: 9px; transition: width .35s; }
.bar-row.pick { font-weight: 800; }
input[type=range] { accent-color: var(--c); width: 100%; }
.step-flow { display: flex; gap: 8px; flex-wrap: wrap; align-items: stretch; }
.step-flow .s { flex: 1; min-width: 110px; padding: 10px 12px; border-radius: 14px; background: #fff; border: 2px solid var(--line2); font-size: 13.5px; transition: all .3s; opacity: .45; }
.step-flow .s b { display: block; font-size: 14px; }
.step-flow .s.on { opacity: 1; border-color: var(--c); box-shadow: 0 6px 18px color-mix(in srgb, var(--c) 22%, transparent); transform: translateY(-3px); }
.step-flow .s.done { opacity: .9; }

/* ---------- Logo ---------- */
.brand .logo-img { width: 42px; height: 42px; display: block; filter: drop-shadow(0 3px 8px rgba(91, 75, 255, .25)); transition: transform .4s; }
.brand:hover .logo-img { transform: rotate(-12deg) scale(1.05); }

/* ---------- 搜索 ---------- */
.search-btn { display: flex; align-items: center; gap: 8px; background: #fff; border: 1.5px solid var(--line2); border-radius: 999px; padding: 7px 10px 7px 14px; color: var(--mute); font: 14px var(--font); cursor: pointer; min-width: 230px; transition: border-color .15s, box-shadow .15s; }
.search-btn:hover { border-color: var(--bl); box-shadow: 0 0 0 4px rgba(61, 139, 253, .12); }
.search-btn .sb-t { flex: 1; text-align: left; }
kbd { font: 600 11px var(--mono); background: #f4efe8; border: 1px solid var(--line2); border-bottom-width: 2px; border-radius: 6px; padding: 1px 6px; color: var(--dim); }
.search-bg { place-items: start center; padding-top: 10vh; }
.search-box { width: min(720px, 100%); padding: 0; overflow: hidden; border-top: 0; }
.search-in { display: flex; align-items: center; gap: 12px; padding: 16px 20px; border-bottom: 1.5px solid var(--line); font-size: 20px; }
.search-in input { flex: 1; border: 0; outline: none; font: 17px var(--font); background: none; color: var(--tx); }
.search-res { max-height: 62vh; overflow: auto; padding: 8px 10px 14px; }
.search-tip { padding: 14px 12px; }
.search-tip .chip { cursor: pointer; border: 1.5px solid var(--line2); background: #fff; font-size: 14px; }
.search-tip .chip:hover { border-color: var(--bl); color: var(--bl); }
.sg { font-size: 12px; font-weight: 800; color: var(--mute); letter-spacing: .1em; padding: 12px 12px 6px; }
.si { display: flex; gap: 12px; align-items: flex-start; padding: 10px 12px; border-radius: 12px; color: var(--tx); }
.si:hover, .si.on { background: var(--cbg, #fff3e6); text-decoration: none; }
.si b { font-size: 15.5px; }
.si em { font-style: normal; font-size: 12px; color: var(--c, var(--mute)); margin-left: 6px; }
.si small { display: block; color: var(--dim); font-size: 13px; line-height: 1.6; margin-top: 2px; }
.si small i { font-style: normal; color: var(--mute); }
.si-no { flex: none; min-width: 40px; text-align: center; font: 800 12px var(--mono); color: #fff; background: var(--c, var(--or)); border-radius: 8px; padding: 3px 6px; margin-top: 2px; }
.si-ic { flex: none; width: 40px; text-align: center; font-weight: 800; color: var(--or); margin-top: 1px; }
mark { background: #ffe08a; color: inherit; border-radius: 3px; padding: 0 1px; }
@media (max-width: 1100px) { .search-btn .sb-t, .search-btn kbd { display: none; } .search-btn { min-width: 0; padding: 7px 12px; } }

/* ---------- 视频 ---------- */
.vplayer { width: 100%; display: block; border-radius: 16px; background: #1d1b2a; aspect-ratio: 16 / 9; }
.vframe { position: relative; aspect-ratio: 16 / 9; border-radius: 16px; overflow: hidden; background: #1d1b2a; }
.vframe iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.vthumb { position: relative; aspect-ratio: 16 / 9; overflow: hidden; background: linear-gradient(135deg, #b2f2d4, #a5e8f3 50%, #ffc9de); display: grid; place-items: center; }
.vthumb > img, .vthumb > video, .vthumb .vprev { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.vthumb .vprev { z-index: 1; }
.vt-ph { font: 900 54px var(--font); color: rgba(255, 255, 255, .9); }
.vplay { position: absolute; z-index: 2; width: 64px; height: 64px; border-radius: 50%; background: rgba(255, 255, 255, .92); color: var(--mg); display: grid; place-items: center; font-size: 24px; padding-left: 5px; box-shadow: 0 8px 24px rgba(0, 0, 0, .18); transition: transform .2s, opacity .2s; }
.vthumb:hover .vplay { transform: scale(1.12); }
.vthumb[data-preview]:hover .vplay { opacity: 0; }
.vdur { position: absolute; z-index: 2; right: 10px; bottom: 10px; background: rgba(20, 18, 30, .78); color: #fff; font: 700 12px var(--mono); padding: 2px 8px; border-radius: 6px; }
.vnone { position: absolute; z-index: 2; left: 10px; bottom: 10px; background: rgba(255, 255, 255, .85); color: var(--dim); font-size: 12px; font-weight: 700; padding: 2px 10px; border-radius: 999px; }
.upbar { height: 10px; border-radius: 5px; background: #f2ece4; overflow: hidden; margin-top: 8px; }
.upbar i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, #ff8a3d, #f7577f, #7d5cf5); transition: width .2s; }

/* ---------- 富文本（讲义深入讲解 / 教学视频正文） ---------- */
.rich h3 { font-size: 20px; margin: 22px 0 10px; }
.rich h4 { font-size: 17px; margin: 18px 0 8px; }
.rich p { margin: 0 0 12px; }
.rich ul { margin: 0 0 14px; padding-left: 22px; } .rich li { margin: 4px 0; } .rich li::marker { color: var(--c); }
.rich .hl { padding: 12px 16px; border-radius: 12px; background: var(--cbg, #fff3e6); border-left: 4px solid var(--c); font-weight: 600; margin: 8px 0 14px; }
.rich figure { margin: 14px 0 18px; } .rich figure img { max-width: 100%; border-radius: 14px; display: block; box-shadow: var(--shadow); }
.rich figcaption { font-size: 13px; color: var(--mute); text-align: center; margin-top: 6px; }
.rich ol { margin: 0 0 14px; padding-left: 24px; } .rich ol li::marker { color: var(--c); font-weight: 800; }
.rich hr { border: 0; height: 2px; background: linear-gradient(90deg, transparent, var(--c), transparent); opacity: .35; margin: 26px 0; }
.rich b { color: var(--tx); font-weight: 800; } .rich a { color: var(--c); text-decoration: underline; text-underline-offset: 3px; }
.rich code { font: 13.5px var(--mono); background: #f5efe7; padding: 1px 6px; border-radius: 6px; }
.rich pre.code { font: 13.5px/1.6 var(--mono); background: #221f30; color: #f3eee8; padding: 16px 18px; border-radius: 14px; overflow: auto; white-space: pre; margin: 8px 0 16px; }
.deep .db h3 { font-size: 18px; margin: 16px 0 8px; } .deep .db figure img { max-width: 100%; border-radius: 12px; }

/* ---------- 导航：链接变多后的适配 ---------- */
.nav .wrap { gap: 18px; }
.nav-links a { white-space: nowrap; padding: 7px 12px; }
@media (max-width: 1400px) { .search-btn .sb-t, .search-btn kbd { display: none; } .search-btn { min-width: 0; padding: 7px 12px; } .nav-user .uname { display: none; } }
@media (max-width: 1080px) {
  .nav-links { display: none; position: absolute; top: 66px; left: 0; right: 0; flex-direction: column; background: var(--bg); padding: 12px 24px; border-bottom: 1px solid var(--line); }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; margin-left: auto; }
}