:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --surface-2: #eef2f7;
  --text: #15233b;
  --text-soft: #5a6b85;
  --border: #dde4ee;
  --primary: #1f5fd6;
  --primary-ink: #ffffff;
  --primary-soft: #e7f0ff;
  --accent: #0f9d7a;
  --warn: #c2410c;
  --warn-soft: #fff1e8;
  --radius: 14px;
  --shadow: 0 6px 22px rgba(20, 40, 80, 0.08);
  --maxw: 1120px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0e1422;
    --surface: #16203a;
    --surface-2: #1d2944;
    --text: #e8eefb;
    --text-soft: #a3b2cf;
    --border: #2a3858;
    --primary: #5b93ff;
    --primary-ink: #0e1422;
    --primary-soft: #1b2c52;
    --accent: #34d6a8;
    --warn: #ff9b6b;
    --warn-soft: #3a2418;
    --shadow: 0 8px 26px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Roboto, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px;
}

a { color: var(--primary); }

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--primary);
  color: var(--primary-ink);
  padding: 10px 16px;
  border-radius: 0 0 8px 0;
  z-index: 50;
}
.skip-link:focus { left: 0; }

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark {
  width: 38px; height: 38px;
  display: grid; place-items: center;
  background: var(--primary);
  color: var(--primary-ink);
  font-weight: 800;
  border-radius: 10px;
  font-size: 18px;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.brand-title { font-weight: 700; font-size: 16px; }
.brand-sub { font-size: 12px; color: var(--text-soft); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  cursor: pointer;
}
.nav-toggle span { width: 20px; height: 2px; background: var(--text); display: block; }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--primary-soft), var(--bg) 70%);
  padding: 48px 0 36px;
}
.hero h1 {
  font-size: clamp(26px, 5vw, 40px);
  margin: 0 0 12px;
  letter-spacing: -0.5px;
}
.hero-lead { margin: 0 0 24px; color: var(--text-soft); max-width: 720px; font-size: clamp(15px, 2.4vw, 17px); }
.hero-lead strong { color: var(--text); }

.stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 0 0 24px;
  padding: 0;
}
.stats li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
}
.stat-num { display: block; font-size: clamp(20px, 4vw, 28px); font-weight: 800; color: var(--primary); }
.stat-label { display: block; font-size: 13px; color: var(--text-soft); margin-top: 2px; }

.search-bar { display: flex; gap: 10px; max-width: 640px; }
.search-bar input {
  flex: 1;
  padding: 13px 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  font-size: 15px;
}
.search-bar input:focus-visible { outline: 3px solid var(--primary); outline-offset: 1px; }

.btn-primary {
  border: none;
  background: var(--primary);
  color: var(--primary-ink);
  padding: 13px 22px;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}
.btn-primary:hover { filter: brightness(1.05); }
.btn-primary:focus-visible { outline: 3px solid var(--text); outline-offset: 2px; }

/* ---------- Board / Filters ---------- */
.board { padding: 28px 20px 56px; }
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: flex-end;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
}
.filter-group { display: flex; flex-direction: column; gap: 6px; }
.filter-group label { font-size: 13px; color: var(--text-soft); font-weight: 600; }
.filter-group select {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-2);
  color: var(--text);
  font-size: 14px;
  min-width: 150px;
}
.filter-group select:focus-visible { outline: 3px solid var(--primary); outline-offset: 1px; }

.btn-ghost {
  margin-left: auto;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-soft);
  padding: 10px 16px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 14px;
}
.btn-ghost:hover { color: var(--text); border-color: var(--text-soft); }

.result-count { color: var(--text-soft); font-size: 14px; margin: 20px 0 14px; }

/* ---------- Cards ---------- */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: transform .15s ease, box-shadow .15s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.card:focus-within { box-shadow: var(--shadow); }

.card-top { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.school {
  font-weight: 700;
  font-size: 15px;
  background: var(--primary-soft);
  color: var(--primary);
  padding: 4px 10px;
  border-radius: 999px;
}
.badge-verified {
  font-size: 12px;
  color: var(--accent);
  border: 1px solid color-mix(in srgb, var(--accent) 40%, var(--border));
  padding: 2px 8px;
  border-radius: 999px;
  white-space: nowrap;
}
.position { font-size: 17px; font-weight: 600; margin: 0; }
.meta { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  font-size: 12px;
  color: var(--text-soft);
  background: var(--surface-2);
  border: 1px solid var(--border);
  padding: 3px 9px;
  border-radius: 8px;
}
.chip.type { color: var(--text); }
.chip.edu { color: var(--text); }
.deadline {
  font-size: 13px;
  color: var(--text-soft);
}
.deadline.soon {
  color: var(--warn);
  background: var(--warn-soft);
  padding: 3px 9px;
  border-radius: 8px;
  font-weight: 600;
  align-self: flex-start;
}
.card-foot { margin-top: auto; padding-top: 6px; }
.card-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  font-size: 14px;
  text-decoration: none;
  border: 1px solid var(--border);
  padding: 9px 14px;
  border-radius: 10px;
}
.card-link:hover { background: var(--primary-soft); border-color: var(--primary); }
.card-link:focus-visible { outline: 3px solid var(--primary); outline-offset: 2px; }

.empty-state {
  text-align: center;
  color: var(--text-soft);
  padding: 48px 0;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--surface);
  padding: 28px 0 36px;
  margin-top: 24px;
}
.foot-note { color: var(--text-soft); font-size: 13px; margin: 0 0 10px; }
.foot-note code { background: var(--surface-2); padding: 1px 6px; border-radius: 6px; }
.foot-meta { color: var(--text-soft); font-size: 12px; margin: 0; }

/* ---------- 响应式 ---------- */
@media (max-width: 720px) {
  .nav-toggle { display: flex; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .filter-bar { display: none; flex-direction: column; align-items: stretch; }
  .filter-bar.open { display: flex; }
  .filter-group select { min-width: 0; width: 100%; }
  .btn-ghost { margin-left: 0; }
  .search-bar { flex-direction: column; }
  .search-bar .btn-primary { width: 100%; }
  .cards { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}