/* === KCode · 通问AI官网 V2 === */
/* 设计原则：克制专业 · 留白优先 · 排版即内容 */

:root {
  --color-brand: #1a56db;
  --color-brand-dark: #1040b0;
  --color-text: #1a1a2e;
  --color-text-secondary: #4a5568;
  --color-bg: #fafbfc;
  --color-white: #ffffff;
  --color-border: #e2e8f0;
  --color-accent: #f0f4ff;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;
  --max-width: 960px;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
}

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

html {
  scroll-behavior: smooth;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.75;
}

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

/* === Nav === */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  padding: 14px 0;
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}
.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-brand);
  text-decoration: none;
  letter-spacing: -0.01em;
}
.nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
}
.nav-links a {
  text-decoration: none;
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  transition: color 0.15s;
}
.nav-links a:hover { color: var(--color-brand); }

/* === Hero === */
.hero {
  padding: 80px 0 64px;
  text-align: center;
}
.hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin-bottom: 16px;
  color: var(--color-text);
}
.hero .subtitle {
  font-size: 1.15rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  margin: 0 auto 32px;
  line-height: 1.7;
}
.hero .cta-group {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-block;
  padding: 12px 32px;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.15s;
  cursor: pointer;
  border: none;
}
.btn-primary {
  background: var(--color-brand);
  color: #fff;
}
.btn-primary:hover { background: var(--color-brand-dark); }
.btn-outline {
  border: 2px solid var(--color-border);
  color: var(--color-text);
  background: transparent;
}
.btn-outline:hover { border-color: var(--color-brand); color: var(--color-brand); }

/* === Section === */
.section {
  padding: 72px 0;
}
.section-alt {
  background: var(--color-white);
}
.section-label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-brand);
  margin-bottom: 8px;
}
.section h2 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 12px;
}
.section h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin: 32px 0 8px;
}
.section .lead {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  margin-bottom: 40px;
  max-width: 720px;
}

/* === Cards === */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
  margin: 32px 0;
}
.card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 24px;
  box-shadow: var(--shadow);
}
.card h4 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 8px;
}
.card p {
  font-size: 0.92rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
}
.card .card-num {
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-brand);
  opacity: 0.15;
  line-height: 1;
  margin-bottom: 8px;
}

/* === Photo Placeholder === */
.photo-placeholder {
  background: var(--color-accent);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  text-align: center;
  padding: 24px;
}
.photo-placeholder .icon {
  font-size: 2rem;
  margin-bottom: 8px;
  opacity: 0.4;
}
.photo-placeholder.small { min-height: 120px; }
.photo-placeholder.large { min-height: 320px; }

/* === Table === */
.table-wrap {
  overflow-x: auto;
  margin: 24px 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}
th {
  font-weight: 700;
  background: var(--color-accent);
  white-space: nowrap;
}
tr:hover td { background: #f8fafc; }

/* === FAQ === */
.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 20px 0;
}
.faq-item .q {
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 8px;
  color: var(--color-text);
}
.faq-item .a {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* === Quote === */
.quote-block {
  background: var(--color-accent);
  border-left: 4px solid var(--color-brand);
  padding: 20px 24px;
  margin: 24px 0;
  border-radius: 0 var(--radius) var(--radius) 0;
}
.quote-block .text {
  font-size: 1.05rem;
  font-style: italic;
  margin-bottom: 8px;
}
.quote-block .author {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 600;
}

/* === Instructor === */
.instructor-duo {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  margin: 32px 0;
}
.instructor-card {
  text-align: center;
}
.instructor-card .photo {
  margin-bottom: 20px;
}
.instructor-card h4 {
  font-size: 1.2rem;
}
.instructor-card .role {
  font-size: 0.9rem;
  color: var(--color-brand);
  font-weight: 600;
  margin: 4px 0 12px;
}
.instructor-card .bio {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  text-align: left;
  line-height: 1.7;
}
.instructor-card .tagline {
  font-size: 0.85rem;
  font-weight: 700;
  margin-top: 12px;
  padding: 8px 16px;
  background: var(--color-accent);
  border-radius: 20px;
  display: inline-block;
}

/* === Stats === */
.stat-row {
  display: flex;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
  margin: 32px 0;
}
.stat-item {
  text-align: center;
}
.stat-item .num {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--color-brand);
  line-height: 1.2;
}
.stat-item .label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-top: 4px;
}

/* === Footer === */
.footer {
  background: var(--color-text);
  color: rgba(255,255,255,0.7);
  padding: 48px 0 32px;
  font-size: 0.85rem;
  line-height: 1.8;
}
.footer a { color: rgba(255,255,255,0.85); }
.footer .footer-brand {
  color: #fff;
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 8px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
}
.footer .meta {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: 0.8rem;
}

/* === Responsive === */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.8rem; }
  .instructor-duo { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .nav-links { display: none; }
  .stat-row { gap: 24px; }
}