/* =========================================
   ISSE - 智能化软件系统与工程
   ========================================= */

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

:root {
  --clr-primary: #0f172a;
  --clr-primary-mid: #1e3a5f;
  --clr-primary-light: #3b82f6;
  --clr-accent: #06b6d4;
  --clr-accent-warm: #8b5cf6;
  --clr-bg: #f8fafc;
  --clr-white: #ffffff;
  --clr-text: #1e293b;
  --clr-text-light: #64748b;
  --clr-border: #e2e8f0;
  --clr-surface: #ffffff;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --max-width: 1080px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont,
    "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--clr-text);
  background: var(--clr-bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

a {
  color: var(--clr-primary-light);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--clr-accent);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  padding: 100px 24px 80px;
  text-align: center;
  color: var(--clr-white);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 40%, #3b82f6 100%);
  z-index: 0;
}

.hero-bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(6, 182, 212, 0.15) 0%, transparent 60%),
    radial-gradient(ellipse at 80% 20%, rgba(139, 92, 246, 0.12) 0%, transparent 50%);
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin-bottom: 12px;
}

.hero .subtitle {
  font-size: 1.1rem;
  opacity: 0.7;
  font-weight: 400;
  margin-bottom: 8px;
}

.hero .meta {
  font-size: 1rem;
  opacity: 0.55;
}

/* ---------- Nav ---------- */
.nav-bar {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--clr-border);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: box-shadow var(--transition);
}

.nav-bar.stuck {
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.06);
}

.nav-inner {
  display: flex;
  gap: 36px;
  padding: 16px 24px;
  overflow-x: auto;
}

.nav-bar a {
  color: var(--clr-text-light);
  font-size: 0.88rem;
  font-weight: 500;
  white-space: nowrap;
  padding-bottom: 4px;
  border-bottom: 2px solid transparent;
  transition: all var(--transition);
}

.nav-bar a:hover,
.nav-bar a.active {
  color: var(--clr-primary);
  border-bottom-color: var(--clr-primary-light);
}

/* ---------- Sections ---------- */
section {
  padding: 64px 0 48px;
}

h2 {
  font-size: 1.65rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--clr-primary);
  letter-spacing: -0.01em;
}

.section-lead {

  margin-bottom: 32px;
  color: var(--clr-text-light);
  font-size: 1rem;
  line-height: 1.8;
  text-align: justify;
}

/* ---------- Card Grid ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.card-grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 32px 28px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.card-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: linear-gradient(135deg, #eff6ff, #dbeafe);
  color: var(--clr-primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}

.card-icon svg {
  width: 22px;
  height: 22px;
}

.card h3 {
  font-size: 1.08rem;
  font-weight: 600;
  color: var(--clr-primary);
  margin-bottom: 10px;
}

.card p {
  font-size: 0.9rem;
  color: var(--clr-text-light);
  line-height: 1.75;
  text-align: justify;
}

/* ---------- Chapter List ---------- */
.chapter-list {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--clr-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.chapter-item {
  display: flex;
  gap: 24px;
  padding: 20px 24px;
  background: var(--clr-surface);
  align-items: center;
  transition: background var(--transition);
}

.chapter-item:hover {
  background: #f1f5f9;
}

.chapter-num {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-mid));
  color: var(--clr-white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.chapter-body {
  flex: 1;
  min-width: 0;
}

.chapter-body h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--clr-primary);
  margin-bottom: 4px;
}

.chapter-body p {
  font-size: 0.88rem;
  color: var(--clr-text-light);
  line-height: 1.7;
  margin-bottom: 8px;
}

.practice-tag {
  display: inline-block;
  padding: 3px 10px;
  margin-bottom: 10px;
  background: linear-gradient(135deg, #dbeafe, #eff6ff);
  color: var(--clr-primary-light);
  border-radius: 4px;
  font-size: 0.78rem;
  font-weight: 500;
}

.chapter-links {
  display: flex;
  gap: 8px;
}

.res-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 14px;
  border: 1px solid var(--clr-border);
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--clr-text-light);
  background: var(--clr-bg);
  transition: all var(--transition);
}

.res-link:hover {
  background: var(--clr-primary-light);
  border-color: var(--clr-primary-light);
  color: var(--clr-white);
}

.res-link-locked {
  opacity: 0.5;
  cursor: not-allowed;
}

.res-link-locked:hover {
  background: var(--clr-bg);
  border-color: var(--clr-border);
  color: var(--clr-text-light);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--clr-primary);
  color: var(--clr-white);
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 0.9rem;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 1000;
  box-shadow: var(--shadow-lg);
}

.toast.show {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

/* ---------- Tool Grid ---------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 16px;
}

.tool-item {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 24px 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 8px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.tool-item:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: transparent;
}

.tool-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, #f0fdf4, #dcfce7);
  color: #16a34a;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 4px;
}

.tool-icon svg {
  width: 20px;
  height: 20px;
}

.tool-item strong {
  font-size: 0.95rem;
  color: var(--clr-primary);
}

.tool-item span {
  font-size: 0.8rem;
  color: var(--clr-text-light);
}

/* ---------- Awards ---------- */
.award-list {
  list-style: none;
  max-width: 780px;
}

.award-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--clr-border);
  font-size: 0.92rem;
  color: var(--clr-text-light);
  line-height: 1.7;
}

.award-list li:last-child {
  border-bottom: none;
}

.award-list li strong {
  color: var(--clr-text);
}

.award-year-tag {
  display: inline-block;
  padding: 1px 8px;
  margin-right: 8px;
  background: #fef3c7;
  color: #92400e;
  border-radius: 4px;
  font-size: 0.78rem;
  font-weight: 600;
  vertical-align: middle;
}

/* ---------- Footer ---------- */
footer {
  background: var(--clr-primary);
  color: rgba(255, 255, 255, 0.5);
  text-align: center;
  padding: 32px 24px;
  font-size: 0.84rem;
  margin-top: 24px;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .hero {
    padding: 64px 16px 48px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .nav-inner {
    gap: 24px;
    padding: 14px 16px;
  }

  section {
    padding: 40px 0 32px;
  }

  h2 {
    font-size: 1.4rem;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .card-grid-3 {
    grid-template-columns: 1fr;
  }

  .chapter-item {
    padding: 16px;
    gap: 16px;
  }

  .chapter-num {
    width: 36px;
    height: 36px;
    font-size: 0.78rem;
  }

  .tool-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .awards-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.6rem;
  }

  .tool-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
}