/* 应子学习 · 主站样式：沿用门户页的浅色卡片风格，手机优先，向上适配 */

:root {
  --brand: #2563b8;
  --brand-dark: #1b4a8f;
  --accent: #0f9b8e;
  --bg: #eef2f9;
  --panel: #ffffff;
  --ink: #1b2130;
  --ink-2: #55617a;
  --ink-3: #8e9ab3;
  --line: #dfe5f1;
  --soft: #eaf1fb;
  --shadow: 0 6px 22px rgba(27, 58, 107, .08);
  --radius: 14px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.72;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--brand); text-decoration: none; }

.wrap {
  max-width: 1040px;
  margin: 0 auto;
  padding: 18px 16px 8px;
}

/* ---------------- 顶部 ---------------- */
.top {
  display: flex; align-items: center; gap: 14px;
  margin-bottom: 22px;
}
.brand { display: flex; align-items: center; gap: 12px; color: inherit; }
.mark {
  width: 44px; height: 44px; flex: 0 0 44px; border-radius: 13px;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff; font-size: 21px; font-weight: 600;
  display: grid; place-items: center;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.3; }
.brand-text strong { font-size: 18px; letter-spacing: .3px; }
.brand-text small { font-size: 12px; color: var(--ink-3); }
.top-right { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.nav-links { display: none; gap: 16px; font-size: 14px; }
.nav-links a { color: var(--ink-2); }
.nav-links a:hover { color: var(--brand); }
.clock { display: none; font-size: 13px; color: var(--ink-3); font-variant-numeric: tabular-nums; }
.icon-btn {
  width: 38px; height: 38px; border: 1px solid var(--line); border-radius: 11px;
  background: var(--panel); color: var(--ink-2); cursor: pointer;
  display: grid; place-items: center;
}
.icon-btn:hover { border-color: var(--brand); color: var(--brand); }
.icon-btn svg { width: 19px; height: 19px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 38px; padding: 8px 16px;
  border: 1px solid var(--line); border-radius: 10px;
  background: var(--panel); color: var(--ink-2);
  font-size: 14px; cursor: pointer; transition: .18s;
}
.btn:hover { transform: translateY(-1px); border-color: var(--brand); color: var(--brand); }
.btn.primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn.primary:hover { background: var(--brand-dark); color: #fff; }
.btn.lg { min-height: 46px; padding: 10px 24px; font-size: 15px; }

/* ---------------- 首屏 ---------------- */
.hero {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
  padding: 26px 22px;
  text-align: center;
}
.hero-icon {
  width: 58px; height: 58px; margin: 0 auto 14px; border-radius: 17px;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff; font-size: 28px; font-weight: 600;
  display: grid; place-items: center;
}
.hero h1 { margin: 0 0 10px; font-size: 24px; line-height: 1.4; }
.hero > p { margin: 0 auto 18px; max-width: 620px; color: var(--ink-2); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-bottom: 18px; }
.hero-points { display: flex; flex-wrap: wrap; gap: 8px 10px; justify-content: center; }
.hero-points span {
  font-size: 12.5px; color: var(--ink-2);
  background: var(--soft); border-radius: 20px; padding: 4px 12px;
}

/* ---------------- 区块与卡片 ---------------- */
.section { margin-top: 30px; }
.section-head { margin-bottom: 14px; }
.section-head h2 { margin: 0 0 4px; font-size: 19px; }
.section-head p { margin: 0; color: var(--ink-2); font-size: 13.5px; }

.cards { display: grid; grid-template-columns: 1fr; gap: 14px; }
.card {
  display: flex; flex-direction: column; gap: 10px;
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px; box-shadow: var(--shadow); transition: .18s;
  color: inherit;
}
a.card:hover { transform: translateY(-2px); border-color: var(--brand); }
.card-head { display: flex; align-items: center; gap: 12px; }
.card-icon {
  width: 42px; height: 42px; flex: 0 0 42px; border-radius: 12px;
  background: var(--soft); color: var(--brand);
  display: grid; place-items: center;
}
.card-icon svg { width: 22px; height: 22px; }
.card-title { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.card-title h3 { margin: 0; font-size: 16.5px; }
.badge { font-size: 11.5px; padding: 1px 9px; border-radius: 20px; background: #e9f7f1; color: #1a8f6a; }
.card > p { margin: 0; font-size: 13.5px; color: var(--ink-2); }
.tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: auto; }
.tag {
  font-size: 11.5px; padding: 2px 9px; border-radius: 20px;
  background: #f2f6fd; border: 1px solid var(--line); color: var(--ink-2);
}
.card-enter { font-size: 12.5px; color: var(--brand); }

/* ---------------- 页脚 ---------------- */
.foot {
  max-width: 1040px; margin: 26px auto 0;
  padding: 20px 16px calc(22px + env(safe-area-inset-bottom));
  color: var(--ink-3); font-size: 12.5px;
}

/* ---------------- 平板与桌面 ---------------- */
@media (min-width: 700px) {
  .wrap { padding: 30px 26px 8px; }
  .nav-links { display: flex; }
  .clock { display: inline; }
  .hero { padding: 40px 34px; }
  .hero h1 { font-size: 28px; }
  .cards { grid-template-columns: 1fr 1fr; gap: 16px; }
  .section { margin-top: 38px; }
}

/* ---------------- 夜间护眼主题 ---------------- */
[data-theme="dark"] {
  --brand: #5b93e0;
  --brand-dark: #85b1ec;
  --accent: #3fc0b0;
  --bg: #0f1319;
  --panel: #171c24;
  --ink: #e6ebf3;
  --ink-2: #a9b4c6;
  --ink-3: #7b8798;
  --line: #262d38;
  --soft: #1c2942;
  --shadow: 0 6px 24px rgba(0, 0, 0, .45);
}
[data-theme="dark"] .mark { color: #0f1319; }
[data-theme="dark"] .btn { background: #1b212a; }
[data-theme="dark"] .btn.primary { background: #3b7ad0; border-color: #3b7ad0; color: #fff; }
[data-theme="dark"] .badge { background: #16302a; color: #4fc79c; }
[data-theme="dark"] .tag { background: #1b212a; }