:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #1f2430;
  --muted: #6b7280;
  --primary: #4f6ef7;
  --primary-dark: #3d55d9;
  --border: #e5e7eb;
  --radius: 14px;
  --shadow: 0 6px 24px rgba(31, 36, 48, 0.06);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "Inter", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: min(960px, 92%);
  margin: 0 auto;
}

/* Header */
.site-header {
  padding: 2.5rem 0 1.5rem;
  text-align: center;
}
.site-header h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.site-header .subtitle {
  color: var(--muted);
  margin-top: 0.4rem;
  font-size: 0.95rem;
}

/* Tabs */
.tabs {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin: 1rem auto 1.5rem;
}
.tab-btn {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--muted);
  padding: 0.5rem 1.4rem;
  border-radius: 999px;
  cursor: pointer;
  font-size: 0.95rem;
  transition: all 0.2s;
}
.tab-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

/* Cards */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.card h2 {
  font-size: 1.1rem;
  margin-bottom: 1rem;
}

textarea#grade {
  width: 100%;
  min-height: 180px;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.8rem;
  font-family: "JetBrains Mono", Consolas, monospace;
  font-size: 0.9rem;
  resize: vertical;
}
textarea#grade:focus { outline: 2px solid var(--primary); border-color: transparent; }

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1rem;
}
select, input[type="text"] {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.55rem 0.8rem;
  font-size: 0.9rem;
  background: #fff;
}
select:focus, input[type="text"]:focus { outline: 2px solid var(--primary); border-color: transparent; }

.btn {
  border: none;
  background: var(--primary);
  color: #fff;
  padding: 0.6rem 1.6rem;
  border-radius: 10px;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 0.2s;
}
.btn:hover { background: var(--primary-dark); }

.hint { color: var(--muted); font-size: 0.82rem; margin-top: 0.5rem; }

.dropzone {
  margin-top: 1rem;
  border: 2px dashed var(--border);
  border-radius: 10px;
  padding: 0.8rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  transition: border-color 0.2s;
}
.dropzone.hover { border-color: var(--primary); color: var(--primary); }

/* Results */
.results {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
}
.result-item {
  background: var(--bg);
  border-radius: 10px;
  padding: 1rem;
  text-align: center;
}
.result-item .label { color: var(--muted); font-size: 0.82rem; }
.result-item .value {
  font-size: 1.4rem;
  font-weight: 700;
  font-family: "JetBrains Mono", Consolas, monospace;
  margin-top: 0.2rem;
}

/* Result table */
.detail-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  margin-top: 0.5rem;
}
.detail-table th, .detail-table td {
  border-bottom: 1px solid var(--border);
  padding: 0.45rem 0.6rem;
  text-align: center;
}
.detail-table th { color: var(--muted); font-weight: 600; background: var(--bg); }

/* Algorithm carousel */
.carousel {
  max-width: 520px;
  margin: 0 auto;
}
.car-viewport {
  overflow: hidden;
  border-radius: var(--radius);
}
.car-track {
  display: flex;
  transition: transform 0.35s ease;
}
.alg-card {
  flex: 0 0 100%;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.25rem 1.5rem;
  opacity: 0.4;
  transition: opacity 0.35s;
}
.alg-card.active { opacity: 1; }
.alg-card h3 {
  font-size: 1rem;
  margin-bottom: 0.7rem;
  text-align: center;
  color: var(--primary-dark);
}
.alg-card table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}
.alg-card th, .alg-card td {
  border-bottom: 1px solid var(--border);
  padding: 0.4rem 0.5rem;
  text-align: center;
}
.alg-card th { color: var(--muted); background: var(--bg); }

.car-nav {
  margin-top: 0.9rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  flex-wrap: wrap;
}
.car-arrow {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  font-size: 1.2rem;
  line-height: 1;
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  z-index: 2;
}
.car-arrow:hover { background: var(--primary); border-color: var(--primary); color: #fff; }

@media (min-width: 720px) {
  .carousel { position: relative; }
  .car-arrow {
    position: absolute;
    top: 45%;
    margin-top: -1rem;
  }
  .car-arrow:first-of-type { left: 0.4rem; }
  .car-arrow:last-of-type { right: 0.4rem; }
}

.car-dots {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  justify-content: center;
}
.car-dot {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--muted);
  padding: 0.3rem 0.8rem;
  border-radius: 999px;
  font-size: 0.78rem;
  cursor: pointer;
  transition: all 0.2s;
}
.car-dot.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  font-weight: 600;
}

.alg-card .desc {
  color: var(--muted);
  font-size: 0.78rem;
  margin-bottom: 0.6rem;
  text-align: center;
}

.alg-card .desc {
  color: var(--muted);
  font-size: 0.78rem;
  margin-bottom: 0.6rem;
  text-align: center;
}
.alg-card h3 {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.alg-card .tag {
  font-size: 0.65rem;
  padding: 0.1rem 0.5rem;
  border-radius: 999px;
  font-weight: 600;
}
.alg-card .tag-official { background: #e3f7e8; color: #1a7f37; }
.alg-card .tag-conv { background: #fdf3d8; color: #9a6700; }
.alg-card h3 .src {
  font-size: 0.68rem;
  color: var(--primary);
  text-decoration: none;
}
.alg-card h3 .src:hover { text-decoration: underline; }

/* Reform list */
.reform-list {
  list-style: none;
}
.reform-list li {
  padding: 0.8rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.88rem;
}
.reform-list li:last-child { border-bottom: none; }
.reform-list strong { color: var(--primary-dark); }
.reform-list a {
  color: var(--primary);
  text-decoration: none;
  font-size: 0.8rem;
  margin-right: 0.6rem;
}
.reform-list a:hover { text-decoration: underline; }

.note { color: var(--muted); font-size: 0.85rem; margin-top: 1rem; }

/* Footer */
.site-footer {
  margin-top: auto;
  padding: 1.5rem 0 2rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.82rem;
  border-top: 1px solid var(--border);
}
.site-footer a { color: var(--muted); text-decoration: none; }
.site-footer a:hover { color: var(--primary); }
.beian {
  margin-top: 0.4rem;
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.hidden { display: none; }