:root {
  --color-bg: #ffffff;
  --color-bg-muted: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e5e7eb;
  --color-text: #111827;
  --color-text-secondary: #6b7280;
  --color-primary: #4f46e5;
  --color-primary-dark: #4338ca;
  --color-primary-soft: #eef2ff;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-card: 0 1px 3px rgba(17, 24, 39, 0.05), 0 1px 2px rgba(17, 24, 39, 0.04);
  --shadow-card-hover: 0 10px 25px -5px rgba(17, 24, 39, 0.08), 0 8px 10px -6px rgba(17, 24, 39, 0.04);
  --max-width: 1080px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Inter", Roboto,
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

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

.nav-brand {
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: 0.02em;
}

.nav-brand::after {
  content: ".";
  color: var(--color-primary);
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  transition: color 0.2s ease;
}

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

.nav-tag {
  display: inline-block;
  padding: 2px 10px;
  border: 1px solid var(--color-primary);
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--color-primary) !important;
}

.nav-tag:hover {
  background: var(--color-primary);
  color: #fff !important;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

/* ---------- Hero ---------- */
.hero {
  padding: 120px 0 110px;
  background:
    radial-gradient(60% 60% at 80% 10%, rgba(79, 70, 229, 0.06), transparent 70%),
    var(--color-bg);
}

.hero-inner {
  max-width: 720px;
}

.hero-eyebrow {
  font-size: 1.05rem;
  color: var(--color-primary);
  margin-bottom: 16px;
}

.hero-name {
  font-size: clamp(3rem, 8vw, 4.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.hero-name .dot {
  color: var(--color-primary);
}

.tvdz-tag {
  display: inline-block;
  margin-top: 18px;
  padding: 4px 14px;
  border: 1px solid var(--color-primary);
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--color-primary);
  transition: all 0.2s ease;
}

.tvdz-tag:hover {
  background: var(--color-primary);
  color: #fff;
  transform: translateY(-1px);
}

.hero-subtitle {
  margin-top: 20px;
  font-size: 1.4rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  min-height: 2.4rem;
  border-right: 2px solid var(--color-primary);
  display: inline-block;
  white-space: nowrap;
  overflow: hidden;
  padding-right: 2px;
}

.hero-desc {
  margin-top: 24px;
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  max-width: 560px;
}

.hero-actions {
  margin-top: 40px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 0.98rem;
  font-weight: 600;
  transition: all 0.2s ease;
}

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

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 6px 18px -6px rgba(79, 70, 229, 0.5);
}

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

.btn-ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-1px);
}

.btn-lg {
  padding: 14px 36px;
  font-size: 1.05rem;
}

/* ---------- Sections ---------- */
.section {
  padding: 110px 0;
}

.section-muted {
  background: var(--color-bg-muted);
  text-align: center;
}

.section-eyebrow {
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.section-title {
  margin-top: 12px;
  font-size: clamp(1.9rem, 4vw, 2.5rem);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.section-subtitle {
  margin-top: 14px;
  color: var(--color-text-secondary);
  font-size: 1.05rem;
}

/* ---------- Skill Cards ---------- */
.skill-grid {
  margin-top: 56px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.skill-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  box-shadow: var(--shadow-card);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
}

.skill-card-head {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 14px;
}

.skill-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-soft);
  color: var(--color-primary);
}

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

.skill-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
}

.skill-desc {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 20px;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-tags li {
  font-size: 0.83rem;
  color: var(--color-text);
  background: var(--color-bg-muted);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 5px 12px;
}

/* ---------- Contact ---------- */
.social-links {
  margin-top: 40px;
  display: flex;
  justify-content: center;
  gap: 18px;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: all 0.2s ease;
}

.social-links a:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.social-links svg {
  width: 22px;
  height: 22px;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 32px 0;
  text-align: center;
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.footer-note {
  margin-top: 6px;
  font-size: 0.82rem;
  opacity: 0.75;
}

/* ---------- Reveal animation ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

.skill-card:nth-child(2) {
  transition-delay: 0.08s;
}

.skill-card:nth-child(3) {
  transition-delay: 0.16s;
}

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  .hero {
    padding: 90px 0 80px;
  }

  .nav-links {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 8px 24px;
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.25s ease, transform 0.25s ease;
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links a {
    display: block;
    padding: 14px 0;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav-toggle.open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

  .nav-toggle.open span:nth-child(2) {
    opacity: 0;
  }

  .nav-toggle.open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  .hero-subtitle {
    font-size: 1.2rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}