/* 平台页面（AI 批改、AI 课件等）共用样式：和首页同一套视觉——宽屏、简洁、系统黑体、浅色底 */
:root{
  --bg:#fff;--soft:#f5f7fb;--ink:#111827;--sub:#4b5565;--mute:#6b7280;--line:#e5e8ef;
  --brand:#3d5afe;--brand-d:#2639c9;--brand-soft:#eef1ff;--brand-ink:#24319a;
  --warn:#8a5a00;--warn-soft:#fff4d6;--ok:#0b7a4f;--ok-bg:#16a06a;--ok-soft:#e6f6ee;--bad:#c2362f;--bad-soft:#fdecec;--grape:#5b3fd6;
  --sans:-apple-system,BlinkMacSystemFont,"Helvetica Neue","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.7 var(--sans);-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
::selection{background:var(--brand-soft);color:var(--ink)}
a:focus-visible,summary:focus-visible,button:focus-visible{outline:2px solid var(--brand);outline-offset:3px;border-radius:8px}
.wrap{max-width:1280px;margin:0 auto;padding:0 40px}
.st{display:inline-block;font-style:normal;font-size:12px;font-weight:700;border-radius:6px;padding:1px 8px;white-space:nowrap;vertical-align:2px}
.st.soon{background:var(--warn-soft);color:var(--warn)}
.st.live{background:var(--ok-soft);color:var(--ok)}
.demo{font-size:12px;font-weight:700;color:var(--warn);background:var(--warn-soft);border-radius:6px;padding:2px 9px;white-space:nowrap}

/* 顶栏 */
.top{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.9);backdrop-filter:saturate(1.6) blur(12px);border-bottom:1px solid var(--line)}
.top .wrap{display:flex;align-items:center;gap:40px;height:68px}
.logo{display:flex;align-items:center;gap:10px;font-size:20px;font-weight:700;letter-spacing:.5px}
.logo i{width:32px;height:32px;border-radius:9px;background:var(--brand);color:#fff;display:grid;place-items:center;font-style:normal;font-weight:800;font-size:17px}
.nav{display:flex;gap:32px;color:var(--sub);font-size:15px}
.nav a:hover,.nav a[aria-current="page"]{color:var(--brand)}
.nav a[aria-current="page"]{font-weight:600}
.acts{margin-left:auto;display:flex;gap:12px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;height:42px;padding:0 20px;border-radius:12px;font-size:15px;font-weight:600;border:1px solid var(--line);background:#fff;color:var(--ink);transition:border-color .15s,box-shadow .15s,background-color .15s;white-space:nowrap}
.btn:hover{border-color:#c9cfdb;box-shadow:0 6px 18px rgba(17,24,39,.08)}
.btn.pri{background:var(--brand);border-color:var(--brand);color:#fff;box-shadow:0 6px 16px rgba(61,90,254,.25)}
.btn.pri:hover{background:var(--brand-d)}
.btn.lg{height:56px;padding:0 34px;font-size:17px;border-radius:14px}

/* 面包屑 */
.crumbs{font-size:14px;color:var(--mute);padding-top:24px}
.crumbs a:hover{color:var(--brand)}

/* 首屏 */
.hero{padding:40px 0 0;text-align:center;background:linear-gradient(180deg,#f3f5ff 0,#fff 520px)}
.hero h1{font-size:60px;line-height:1.15;margin:48px auto 22px;font-weight:800;letter-spacing:.02em;text-wrap:balance}
.hero h1 em{font-style:normal;color:var(--brand)}
.lead{font-size:20px;color:var(--sub);margin:0 auto 38px;max-width:34em;text-wrap:pretty}
.cta{display:flex;gap:16px;justify-content:center;flex-wrap:wrap}
.note{font-size:14px;color:var(--sub);margin-top:18px}
.shot{max-width:1120px;margin:64px auto 0;text-align:left;background:#fff;border:1px solid var(--line);border-bottom:0;border-radius:24px 24px 0 0;box-shadow:0 -10px 60px rgba(31,43,107,.06),0 30px 80px rgba(31,43,107,.12);overflow:hidden}

/* 区块 */
section{padding:120px 0}
section.alt{background:var(--soft)}
.sec-hd{text-align:center;max-width:38em;margin:0 auto 60px}
.sec-hd h2{font-size:42px;line-height:1.25;margin:0 0 16px;font-weight:800;text-wrap:balance}
.sec-hd p{font-size:18px;color:var(--sub);margin:0}

/* 带上边线的条目网格（不用卡片） */
.cols{display:grid;gap:40px 36px;max-width:1120px;margin:0 auto}
.cols.c2{grid-template-columns:repeat(2,minmax(0,1fr))}
.cols.c3{grid-template-columns:repeat(3,minmax(0,1fr))}
.cols.c4{grid-template-columns:repeat(4,minmax(0,1fr))}
.item{border-top:2px solid var(--ink);padding-top:20px;min-width:0}
.item h3{font-size:21px;margin:0 0 8px;line-height:1.4}
.item p{margin:0 0 12px;color:var(--sub)}
.item .ex{background:var(--soft);border-radius:12px;padding:12px 14px;font-size:14px;color:var(--sub)}
section.alt .item .ex{background:#fff}
.item .ex b{color:var(--ink);font-weight:600}

/* 流程 */
.steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));max-width:1120px;margin:0 auto;list-style:none;padding:0;counter-reset:s}
.steps li{padding:0 28px;position:relative}
.steps li:first-child{padding-left:0}
.steps li + li::before{content:"";position:absolute;left:-12px;top:12px;width:20px;height:2px;background:#c9cfdb}
.steps li + li::after{content:"";position:absolute;left:1px;top:8px;width:7px;height:7px;border-top:2px solid #c9cfdb;border-right:2px solid #c9cfdb;transform:rotate(45deg)}
.steps b{display:block;font-size:19px;margin-bottom:6px}
.steps span{color:var(--sub);font-size:15px}

/* 左文右图 */
.split{display:grid;grid-template-columns:5fr 7fr;gap:72px;align-items:center}
.split.rev{grid-template-columns:7fr 5fr}
.split h2{font-size:42px;line-height:1.25;margin:0 0 20px;font-weight:800}
.split > div > p{font-size:18px;color:var(--sub);margin:0 0 28px}
.feat{list-style:none;margin:0;padding:0;display:grid;gap:18px}
.feat li{padding-left:22px;position:relative}
.feat li::before{content:"";position:absolute;left:0;top:10px;width:10px;height:10px;border-radius:50%;border:3px solid var(--brand)}
.feat b{display:block;font-size:18px}
.feat span{color:var(--sub);font-size:15px}

/* 示意面板 */
.panel{background:#fff;border:1px solid var(--line);border-radius:20px;box-shadow:0 30px 80px rgba(31,43,107,.12);overflow:hidden;min-width:0}
.panel .hd{display:flex;align-items:center;gap:12px;padding:20px 26px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.panel .hd b{font-size:18px}
.panel .hd .m{color:var(--mute);font-size:14px}
.panel .hd .demo{margin-left:auto}
.panel .sum{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));border-bottom:1px solid var(--line)}
.panel .sum div{padding:16px 26px;border-left:1px solid var(--line)}
.panel .sum div:first-child{border-left:0}
.panel .sum b{display:block;font-size:24px;line-height:1.3}
.panel .sum span{font-size:13px;color:var(--mute)}
.panel table{width:100%;border-collapse:collapse;font-size:14px}
.panel th{font-weight:500;color:var(--mute);text-align:left;padding:12px 26px;background:#fafbfd;font-size:13px}
.panel td{padding:12px 26px;border-top:1px solid var(--line);font-variant-numeric:tabular-nums;vertical-align:top}
.panel td.n,.panel th.n{text-align:right}
.panel .why{color:var(--sub)}
.panel .foot{padding:14px 26px;border-top:1px solid var(--line);background:var(--brand-soft);color:var(--brand-ink);font-size:14px}
.ok{color:var(--ok);font-weight:700}
.no{color:var(--bad);font-weight:700}
.unsure{color:var(--warn);font-weight:700}
.frac{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;font-size:12px;line-height:1.1;margin:0 2px}
.frac i{font-style:normal;border-top:1px solid currentColor;padding-top:1px}

/* 常见问题 */
.faq{max-width:820px;margin:0 auto}
details{border-bottom:1px solid var(--line);padding:22px 0}
summary{cursor:pointer;font-weight:600;font-size:18px;list-style:none;display:flex;justify-content:space-between;gap:16px}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";color:var(--mute);font-weight:400;font-size:24px;line-height:1}
details[open] summary::after{content:"−"}
details p{color:var(--sub);margin:12px 0 0}

/* 相关页面 */
.next{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px;max-width:1120px;margin:0 auto}
.next a{display:block;border:1px solid var(--line);border-radius:18px;padding:24px 26px;background:#fff;transition:border-color .15s,box-shadow .15s}
.next a:hover{border-color:#c9cfdb;box-shadow:0 10px 30px rgba(17,24,39,.08)}
.next b{display:block;font-size:19px;margin-bottom:4px}
.next span{color:var(--sub);font-size:15px}

.final{text-align:center;background:var(--brand);color:#fff;border-radius:28px;padding:88px 24px}
.final h2{font-size:44px;margin:0 0 14px;font-weight:800}
.final p{margin:0 0 34px;font-size:18px;color:#fff}
.final .btn{background:#fff;color:var(--brand-d);border-color:#fff}
footer{border-top:1px solid var(--line);padding:40px 0;color:var(--mute);font-size:14px}
footer .wrap{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap}
footer a{display:inline-block;padding:6px 0;margin-left:24px}
footer a:hover{color:var(--brand)}

@media (max-width:1024px){
  .wrap{padding:0 24px}
  .nav{display:none}
  .hero h1{font-size:44px}
  section{padding:84px 0}
  .sec-hd h2,.split h2{font-size:32px}
  .cols.c3,.cols.c4{grid-template-columns:repeat(2,minmax(0,1fr))}
  .steps{grid-template-columns:repeat(2,minmax(0,1fr));gap:32px 0}
  .steps li:nth-child(3){padding-left:0}
  .steps li:nth-child(3)::before,.steps li:nth-child(3)::after{display:none}
  .split,.split.rev{grid-template-columns:minmax(0,1fr);gap:48px}
  .next{grid-template-columns:minmax(0,1fr)}
}
@media (max-width:560px){
  .wrap{padding:0 16px}
  .acts{gap:8px}
  .acts .btn{height:38px;padding:0 14px;font-size:14px;border-radius:10px}
  .hero h1{font-size:32px;letter-spacing:0}
  .lead{font-size:16px}
  .btn.lg{height:50px;padding:0 24px;font-size:16px}
  .shot{margin-top:48px;border-radius:18px 18px 0 0}
  .cols.c2,.cols.c3,.cols.c4{grid-template-columns:minmax(0,1fr);gap:32px}
  .steps{grid-template-columns:minmax(0,1fr)}
  .steps li{padding:0}
  .steps li + li::before,.steps li + li::after{display:none}
  .panel .hd,.panel th,.panel td,.panel .foot{padding-left:16px;padding-right:16px}
  .panel .sum div{padding:12px 16px}
  .panel .hide-m{display:none}
  .final{padding:56px 20px;border-radius:20px}
  .final h2{font-size:28px}
  footer a{margin:0 16px 0 0}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .btn,.next a{transition:none}
}