/* Ada AI Lab 首页 · 与 ada.adaailab.com 同一套视觉:Archivo + 单一红色 + 零圆角 + 2px 分割线 */
@font-face { font-family: 'Archivo'; font-style: normal; font-weight: 400 800; font-display: swap; src: url('/fonts/archivo.woff2') format('woff2'); }
:root {
  --bg: #f3f2f2; --paper: #ffffff; --ink: #141414; --muted: #6b6b6b; --line: #d9d7d3;
  --red: #ec3013; --red-d: #c4250d; --green: #2f8f4e; --cream: #fff4e6;
  --head: "Archivo", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --body: -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --max: 1120px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: var(--body); line-height: 1.6; -webkit-font-smoothing: antialiased; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3 { font-family: var(--head); letter-spacing: -0.01em; margin: 0; }
.skip { position: absolute; left: -999px; top: 0; background: var(--ink); color: #fff; padding: 8px 12px; }
.skip:focus { left: 12px; z-index: 99; }
.mark { font-family: var(--head); font-weight: 800; letter-spacing: 0.04em; color: var(--red); }
.kicker { font-family: var(--head); font-size: 12px; font-weight: 700; letter-spacing: 0.14em; text-transform: uppercase; color: var(--red); margin-bottom: 12px; }
.muted { color: var(--muted); }
.small { font-size: 13px; }

/* 顶栏 */
.top { max-width: var(--max); margin: 0 auto; padding: 22px 24px; display: flex; align-items: center; justify-content: space-between; gap: 16px; border-bottom: 2px solid var(--ink); }
.brand { display: flex; align-items: baseline; gap: 8px; font-family: var(--head); font-weight: 800; font-size: 20px; letter-spacing: 0.04em; }
.brand-t small { display: block; font-family: var(--body); font-size: 11px; font-weight: 500; letter-spacing: 0; color: var(--muted); margin-top: -2px; }
.nav { display: flex; align-items: center; gap: 22px; font-size: 14px; font-weight: 600; }
.nav a { padding: 6px 0; border-bottom: 2px solid transparent; }
.nav a:hover { border-color: var(--red); }
.nav-cta { color: var(--red); }

/* Hero */
.hero { max-width: var(--max); margin: 0 auto; padding: 56px 24px 40px; display: grid; grid-template-columns: 1.05fr 1fr; gap: 40px; align-items: center; }
.hero h1 { font-size: clamp(36px, 5.2vw, 60px); line-height: 1.12; font-weight: 800; }
.lede { font-size: 17px; color: #3a3a3a; margin: 20px 0 26px; max-width: 34em; }
.cta-row { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 26px; }
.btn { display: inline-block; padding: 14px 22px; font-family: var(--head); font-weight: 700; font-size: 15px; border: 2px solid var(--ink); transition: transform .12s, background .15s, color .15s; }
.btn:active { transform: scale(.97); }
.btn-primary { background: var(--red); border-color: var(--red); color: #fff; }
.btn-primary:hover { background: var(--red-d); border-color: var(--red-d); }
.btn-ghost { background: transparent; color: var(--ink); }
.btn-ghost:hover { background: var(--ink); color: #fff; }
.facts { list-style: none; margin: 30px 0 0; padding: 18px 0 0; display: flex; gap: 32px; border-top: 2px solid var(--line); }
.facts b { display: block; font-family: var(--head); font-size: 30px; font-weight: 800; line-height: 1; color: var(--red); }
.facts span { font-size: 13px; color: var(--muted); }
.hero-art { margin: 0; border: 2px solid var(--ink); background: var(--cream); }
.hero-art img { aspect-ratio: 3 / 2; object-fit: cover; }
.hero-art figcaption { font-size: 12px; color: var(--muted); padding: 8px 12px; border-top: 2px solid var(--ink); background: #fff; }

/* 通用区块 */
.sec { max-width: var(--max); margin: 0 auto; padding: 56px 24px 24px; }
.sec-head { border-top: 2px solid var(--ink); padding-top: 18px; margin-bottom: 26px; }
.sec-head h2 { font-size: clamp(26px, 3.4vw, 38px); font-weight: 800; }
.sec-head p { margin: 10px 0 0; max-width: 46em; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.grid4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }

/* 学习基地卡 */
.base { display: flex; flex-direction: column; gap: 12px; background: var(--paper); border: 2px solid var(--ink); padding: 24px; transition: transform .15s, box-shadow .15s; }
.base:hover { transform: translateY(-3px); box-shadow: 6px 6px 0 var(--ink); }
.base-nina { background: var(--cream); }
.base-top { display: flex; justify-content: space-between; align-items: center; }
.tag { font-family: var(--head); font-size: 12px; font-weight: 700; letter-spacing: .08em; color: var(--red); border: 2px solid var(--red); padding: 3px 8px; }
.arrow { font-family: var(--head); font-size: 22px; font-weight: 800; }
.base h3 { font-size: 28px; font-weight: 800; }
.base p { font-size: 16px; }
.base p { margin: 0; color: #3a3a3a; }
.chips { list-style: none; margin: 4px 0 0; padding: 0; display: flex; flex-wrap: wrap; gap: 8px; }
.chips li { font-size: 12px; font-weight: 600; padding: 4px 8px; background: var(--bg); border: 1px solid var(--line); }
.base-nina .chips li { background: #fff; }
.link { font-family: var(--head); font-size: 13px; font-weight: 700; color: var(--red); margin-top: auto; padding-top: 8px; }

/* 游戏卡 */
.game { display: flex; flex-direction: column; gap: 8px; background: var(--paper); border: 2px solid var(--ink); padding: 20px 18px; min-height: 240px; transition: transform .15s, box-shadow .15s; }
.game:hover { transform: translateY(-3px); box-shadow: 6px 6px 0 var(--red); }
.g-ico { font-size: 34px; line-height: 1; }
.game h3 { font-size: 18px; font-weight: 800; }
.game p { margin: 0; font-size: 14px; color: #3a3a3a; flex: 1; }
.g-meta { font-size: 12px; color: var(--muted); border-top: 2px solid var(--line); padding-top: 8px; }

/* 怎么学 */
.rules { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; border: 2px solid var(--ink); background: var(--paper); }
.rules li { padding: 22px 20px; border-right: 2px solid var(--ink); }
.rules li:last-child { border-right: 0; }
.rules .n { font-family: var(--head); font-size: 40px; font-weight: 800; color: var(--red); line-height: 1; display: block; margin-bottom: 10px; }
.rules h3 { font-size: 17px; font-weight: 800; margin-bottom: 6px; }
.rules p { margin: 0; font-size: 14px; color: #3a3a3a; }

/* 日志 */
.log { list-style: none; margin: 0; padding: 0; border-top: 2px solid var(--line); }
.log li { display: grid; grid-template-columns: 120px 1fr; gap: 16px; padding: 14px 0; border-bottom: 2px solid var(--line); }
.log time { font-family: var(--head); font-weight: 700; color: var(--red); font-size: 14px; }
.log b { display: block; font-size: 16px; margin-bottom: 2px; }
.log div { color: #3a3a3a; font-size: 14px; }
.log a, .sec .muted a { color: var(--red); font-weight: 700; }

/* 页脚 */
.foot { max-width: var(--max); margin: 40px auto 0; padding: 26px 24px 48px; border-top: 2px solid var(--ink); display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.foot-brand { font-family: var(--head); font-weight: 800; letter-spacing: .04em; }
.foot-links { display: flex; flex-wrap: wrap; gap: 18px; font-size: 14px; font-weight: 600; }
.foot-links a:hover { color: var(--red); }
.foot-note { font-size: 12px; color: var(--muted); }

/* 入场动效(尊重减少动态偏好) */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .5s ease, transform .5s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } html { scroll-behavior: auto; } }

/* 响应式 */
@media (max-width: 960px) {
  .hero { grid-template-columns: 1fr; padding-top: 36px; }
  .hero-art { order: -1; }
  .grid4 { grid-template-columns: 1fr 1fr; }
  .rules { grid-template-columns: 1fr 1fr; }
  .rules li:nth-child(2) { border-right: 0; }
  .rules li:nth-child(-n+2) { border-bottom: 2px solid var(--ink); }
}
@media (max-width: 640px) {
  .top { flex-direction: column; align-items: flex-start; padding: 16px 18px; }
  .nav { gap: 14px; flex-wrap: wrap; font-size: 13px; }
  .hero, .sec { padding-left: 18px; padding-right: 18px; }
  .hero h1 { font-size: 34px; }
  .lede { font-size: 15px; }
  .facts { gap: 20px; }
  .grid2, .grid4, .rules { grid-template-columns: 1fr; }
  .rules li { border-right: 0; border-bottom: 2px solid var(--ink); }
  .rules li:last-child { border-bottom: 0; }
  .log li { grid-template-columns: 1fr; gap: 4px; }
  .foot { grid-template-columns: 1fr; }
}