/* ============================================================
   Skills Hub 官网 — 极简科技风
   支持深色/浅色双主题
   ============================================================ */

/* -------- CSS Variables / Themes -------- */
:root {
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Inter", system-ui, sans-serif;
  --font-display: "SF Pro Display", "Inter", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", ui-monospace, monospace;
  --radius: 14px;
  --radius-sm: 8px;
  --radius-full: 999px;
  --transition: 0.25s cubic-bezier(.4,0,.2,1);
  --transition-slow: 0.5s cubic-bezier(.4,0,.2,1);
}

[data-theme="dark"] {
  --bg: #0a0a0b;
  --bg-alt: #111113;
  --surface: #18181b;
  --surface2: #1f1f23;
  --border: rgba(255,255,255,0.08);
  --border2: rgba(255,255,255,0.12);
  --fg: #f4f4f5;
  --fg-secondary: #a1a1aa;
  --fg-tertiary: #71717a;
  --accent: #22c55e;
  --accent-hover: #16a34a;
  --accent-soft: rgba(34,197,94,0.1);
  --gradient-from: #22c55e;
  --gradient-to: #06b6d4;
  --glow: rgba(34,197,94,0.15);
  --nav-bg: rgba(10,10,11,0.8);
  --card-hover: #222227;
  --cta-bg: linear-gradient(135deg, rgba(34,197,94,0.08) 0%, rgba(6,182,212,0.08) 100%);
}

[data-theme="light"] {
  --bg: #fafafa;
  --bg-alt: #f4f4f5;
  --surface: #ffffff;
  --surface2: #f4f4f5;
  --border: rgba(0,0,0,0.08);
  --border2: rgba(0,0,0,0.12);
  --fg: #18181b;
  --fg-secondary: #52525b;
  --fg-tertiary: #a1a1aa;
  --accent: #16a34a;
  --accent-hover: #15803d;
  --accent-soft: rgba(22,163,74,0.08);
  --gradient-from: #16a34a;
  --gradient-to: #0891b2;
  --glow: rgba(22,163,74,0.1);
  --nav-bg: rgba(250,250,250,0.85);
  --card-hover: #fafafa;
  --cta-bg: linear-gradient(135deg, rgba(22,163,74,0.06) 0%, rgba(8,145,178,0.06) 100%);
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  transition: background var(--transition-slow), color var(--transition-slow);
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; height: auto; display: block; }
button { font: inherit; cursor: pointer; border: 0; background: none; color: inherit; }

.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* -------- Nav -------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: 64px;
  background: var(--nav-bg);
  backdrop-filter: blur(16px) saturate(1.5);
  -webkit-backdrop-filter: blur(16px) saturate(1.5);
  border-bottom: 1px solid var(--border);
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font: 600 17px/1 var(--font-display);
  color: var(--fg);
  flex-shrink: 0;
}

.nav-logo {
  width: 28px;
  height: 28px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 8px 16px;
  font-size: 14px;
  font-weight: 500;
  color: var(--fg-secondary);
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}

.nav-link:hover {
  color: var(--fg);
  background: var(--surface);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

.nav-gh {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 500;
  color: var(--fg-secondary);
  transition: color var(--transition), background var(--transition);
  border: 1px solid var(--border);
}

/* Language toggle */
.lang-toggle {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 12px;
  border-radius: var(--radius-full);
  color: var(--fg-secondary);
  transition: color var(--transition), background var(--transition), border-color var(--transition);
  border: 1px solid var(--border);
  font-size: 13px;
  font-weight: 500;
}

.lang-toggle:hover {
  color: var(--fg);
  background: var(--surface);
  border-color: var(--border2);
}

.lang-toggle svg {
  width: 16px;
  height: 16px;
  opacity: 0.7;
}

.lang-toggle:hover svg {
  opacity: 1;
}

.lang-label {
  min-width: 44px;
  text-align: left;
}

.nav-gh:hover {
  color: var(--fg);
  background: var(--surface);
  border-color: var(--border2);
}

.nav-gh svg {
  width: 18px;
  height: 18px;
}

.theme-toggle {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border-radius: var(--radius-sm);
  color: var(--fg-secondary);
  transition: color var(--transition), background var(--transition);
  border: 1px solid var(--border);
}

.theme-toggle:hover {
  color: var(--fg);
  background: var(--surface);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }
[data-theme="light"] .sun-icon { display: none; }
[data-theme="light"] .moon-icon { display: block; }

.nav-mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
}

.nav-mobile-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--fg);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

/* -------- Hero -------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 96px 0 64px;
  overflow: hidden;
}

.hero-bg-glow {
  position: absolute;
  top: -20%;
  right: -10%;
  width: 60%;
  height: 80%;
  background: radial-gradient(ellipse at center, var(--glow) 0%, transparent 70%);
  pointer-events: none;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  position: relative;
}

.hero-text {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  padding: 6px 14px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  border-radius: var(--radius-full);
  width: fit-content;
}

.hero-title {
  font: 700 clamp(36px, 5vw, 56px)/1.1 var(--font-display);
  letter-spacing: -0.03em;
}

.gradient-text {
  background: linear-gradient(135deg, var(--gradient-from), var(--gradient-to));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-sub {
  font-size: clamp(16px, 1.3vw, 18px);
  color: var(--fg-secondary);
  max-width: 520px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.hero-metrics {
  display: flex;
  gap: 32px;
  margin-top: 8px;
}

.metric {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.metric-value {
  font: 700 20px/1 var(--font-display);
  color: var(--fg);
}

.metric-label {
  font-size: 13px;
  color: var(--fg-tertiary);
}

/* Screenshot */
.hero-visual {
  position: relative;
}

.hero-screenshot-wrap {
  position: relative;
}

.screenshot-frame {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 24px rgba(0,0,0,0.12), 0 1px 4px rgba(0,0,0,0.06);
  transition: box-shadow var(--transition);
}

.frame-dots {
  display: flex;
  gap: 8px;
  padding: 14px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.frame-dots span {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.frame-dots span:nth-child(1) { background: #ff5f57; }
.frame-dots span:nth-child(2) { background: #febc2e; }
.frame-dots span:nth-child(3) { background: #28c840; }

.hero-screenshot {
  width: 100%;
  height: auto;
  display: block;
}

.screenshot-glow {
  position: absolute;
  inset: -40px;
  background: radial-gradient(ellipse at center, var(--glow) 0%, transparent 60%);
  pointer-events: none;
  z-index: -1;
}

/* -------- Sections -------- */
.section {
  padding: 100px 0;
}

.section-alt {
  background: var(--bg-alt);
}

.section-header {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 56px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.section-badge {
  display: inline-flex;
  padding: 6px 14px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.section-title {
  font: 700 clamp(28px, 3.5vw, 40px)/1.2 var(--font-display);
  letter-spacing: -0.02em;
}

.section-desc {
  font-size: 17px;
  color: var(--fg-secondary);
  line-height: 1.7;
}

/* -------- Agents Grid -------- */
.agents-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.agent-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 28px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
  cursor: default;
}

.agent-card:hover {
  transform: translateY(-4px);
  border-color: var(--border2);
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
}

.agent-icon-wrap {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: var(--agent-bg, var(--accent-soft));
}

.agent-icon-wrap svg {
  width: 100%;
  height: 100%;
}

.agent-name {
  font: 600 14px/1 var(--font-display);
}

.agent-more {
  justify-content: center;
  background: transparent;
  border: 1px dashed var(--border);
}

.agent-more:hover {
  border-color: var(--border2);
  background: var(--surface);
}

.agent-more-text {
  font-size: 14px;
  font-weight: 500;
  color: var(--fg-tertiary);
}

/* -------- Features -------- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.feature-card {
  padding: 32px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.feature-card:hover {
  border-color: var(--border2);
  box-shadow: 0 4px 20px rgba(0,0,0,0.06);
  background: var(--card-hover);
}

.feature-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  margin-bottom: 16px;
  background: var(--accent-soft);
  color: var(--accent);
}

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

.feature-title {
  font: 600 18px/1.3 var(--font-display);
  margin-bottom: 8px;
}

.feature-desc {
  font-size: 15px;
  color: var(--fg-secondary);
  line-height: 1.7;
}

/* -------- Showcase -------- */
.showcase-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-bottom: 48px;
}

.showcase-card {
  text-align: center;
  padding: 36px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.showcase-icon {
  width: 48px;
  height: 48px;
  margin: 0 auto 16px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--accent-soft);
  color: var(--accent);
}

.showcase-icon svg {
  width: 24px;
  height: 24px;
}

.showcase-card h4 {
  font: 600 16px/1.3 var(--font-display);
  margin-bottom: 6px;
}

.showcase-card p {
  font-size: 14px;
  color: var(--fg-secondary);
  line-height: 1.6;
}

.screenshot-large {
  max-width: 900px;
  margin: 0 auto;
}

/* -------- Tech Stack -------- */
.tech-stack {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

.tech-items {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

.tech-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--fg-secondary);
}

.tech-item svg {
  width: 18px;
  height: 18px;
  opacity: 0.5;
}

.tech-badge {
  padding: 4px 12px;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: var(--radius-full);
  font-size: 12px;
  font-weight: 600;
}

/* -------- Download -------- */
.download-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  max-width: 700px;
  margin: 0 auto;
}

.download-card {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.download-card:hover {
  transform: translateY(-3px);
  border-color: var(--border2);
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
}

.download-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--accent-soft);
  color: var(--accent);
  flex-shrink: 0;
}

.download-icon svg {
  width: 24px;
  height: 24px;
}

.download-info h3 {
  font: 600 15px/1.3 var(--font-display);
  margin-bottom: 4px;
}

.download-desc {
  font-size: 13px;
  color: var(--fg-tertiary);
}

.source-card {
  grid-column: 1 / -1;
}

.download-note {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 14px 20px;
  margin-top: 20px;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--fg-tertiary);
  line-height: 1.5;
}

.download-note svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: var(--accent);
}

/* -------- CTA -------- */
.cta-section {
  padding-bottom: 0;
}

.cta-card {
  text-align: center;
  padding: 80px 40px;
  background: var(--cta-bg);
  border: 1px solid var(--border);
  border-radius: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.cta-title {
  font: 700 clamp(28px, 3vw, 38px)/1.2 var(--font-display);
  letter-spacing: -0.02em;
}

.cta-desc {
  font-size: 17px;
  color: var(--fg-secondary);
  max-width: 480px;
}

/* -------- Footer -------- */
.footer {
  padding: 60px 0 40px;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font: 600 16px/1 var(--font-display);
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
}

.footer-col h4 {
  font: 600 13px/1 var(--font-display);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--fg-tertiary);
  margin-bottom: 16px;
}

.footer-col a,
.footer-col span {
  display: block;
  font-size: 14px;
  color: var(--fg-secondary);
  margin-bottom: 8px;
  transition: color var(--transition);
}

.footer-col a:hover {
  color: var(--fg);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  font-size: 13px;
  color: var(--fg-tertiary);
}

/* -------- Buttons -------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: scale(1.02);
}

.btn-outline {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--fg);
}

.btn-outline:hover {
  border-color: var(--border2);
  background: var(--surface);
}

.btn-lg {
  padding: 14px 32px;
  font-size: 16px;
}

/* -------- Animations -------- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

.fade-in {
  animation: fadeInUp 0.6s ease forwards;
}

/* -------- Responsive -------- */
@media (max-width: 968px) {
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
  }
  .hero-text { align-items: center; }
  .hero-sub { max-width: 100%; }
  .hero-metrics { justify-content: center; }
  .hero-actions { justify-content: center; }
  .hero-visual { order: -1; }
  .agents-grid { grid-template-columns: repeat(4, 1fr); }
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-mobile-toggle { display: flex; }

  .agents-grid { grid-template-columns: repeat(2, 1fr); }
  .features-grid { grid-template-columns: 1fr; }
  .showcase-grid { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: 1fr; }

  .footer-links { grid-template-columns: 1fr; gap: 24px; }
  .footer-bottom { flex-direction: column; gap: 4px; }

  .section { padding: 60px 0; }
}

@media (max-width: 480px) {
  .hero-metrics { gap: 20px; }
  .hero-metrics .metric:not(:first-child) { display: none; }
}

/* Mobile nav open state */
.nav-open .nav-links {
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 64px;
  left: 0;
  right: 0;
  background: var(--nav-bg);
  backdrop-filter: blur(20px);
  padding: 16px;
  border-bottom: 1px solid var(--border);
  gap: 4px;
}