:root {
  --bg: #ffffff;
  --bg-alt: #f6f6f4;
  --text: #1a1a1a;
  --text-muted: #6b6b6b;
  --accent: #6c5ce7;
  --border: #e8e8e6;
  --card-bg: #ffffff;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
  --max-width: 720px;
}

[data-theme="dark"] {
  --bg: #111113;
  --bg-alt: #18181b;
  --text: #ededed;
  --text-muted: #9a9a9a;
  --accent: #8b7cf7;
  --border: #26262b;
  --card-bg: #18181b;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.35);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  transition: background 0.3s ease, color 0.3s ease;
}

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

/* Navigation */
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: background 0.3s ease;
}

[data-theme="dark"] .nav {
  background: rgba(17, 17, 19, 0.8);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text);
  text-decoration: none;
}

.links {
  display: flex;
  gap: 24px;
}

.links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.2s ease;
}

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

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  padding: 6px;
  display: flex;
  align-items: center;
  transition: color 0.2s ease;
}

.theme-toggle:hover {
  color: var(--accent);
}

.icon-moon {
  display: none;
}

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

[data-theme="dark"] .icon-moon {
  display: block;
}

/* Hero */
.hero {
  padding: 120px 0 96px;
  text-align: center;
}

.hero-title {
  font-size: clamp(2.4rem, 6vw, 4rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 20px;
}

.accent {
  color: var(--accent);
}

.hero-sub {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-muted);
  max-width: 520px;
  margin: 0 auto 40px;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(108, 92, 231, 0.35);
}

.btn-primary:hover {
  box-shadow: 0 6px 20px rgba(108, 92, 231, 0.45);
}

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

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Sections */
.section {
  padding: 96px 0;
}

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

.section-title {
  font-size: clamp(1.6rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.section-text {
  color: var(--text-muted);
  margin-bottom: 40px;
}

.about-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

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

.card h3 {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.card p {
  color: var(--text-muted);
  font-size: 0.92rem;
}

/* Contact */
.contact-list {
  display: grid;
  gap: 12px;
}

.contact-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 24px;
  border: 1px solid var(--border);
  border-radius: 12px;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.contact-item:hover {
  border-color: var(--accent);
  transform: translateX(4px);
}

.contact-label {
  font-weight: 600;
  font-size: 0.92rem;
}

.contact-value {
  color: var(--text-muted);
  font-size: 0.92rem;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
}

.footer p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Reveal animation */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 560px) {
  .hero {
    padding: 96px 0 72px;
  }

  .contact-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }
}