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

:root {
  --primary: #2563eb;
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

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

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
}

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

a:hover {
  text-decoration: underline;
}

/* Header */
.header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 32px;
}

.nav-links a {
  color: var(--text-secondary);
  font-weight: 500;
}

.nav-links a:hover {
  color: var(--primary);
  text-decoration: none;
}

/* Hero */
.hero {
  background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
  color: white;
  padding: 80px 0;
  text-align: center;
}

.hero.small {
  padding: 60px 0;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 16px;
}

.subtitle {
  font-size: 1.25rem;
  color: #94a3b8;
  margin-bottom: 16px;
}

.slogan {
  font-size: 1.125rem;
  color: #cbd5e1;
  max-width: 600px;
  margin: 0 auto;
}

/* Section */
.section {
  padding: 60px 0;
}

.section h2 {
  font-size: 1.875rem;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--primary);
}

.section p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 720px;
}

/* Tech Grid */
.tech-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.tech-item {
  background: var(--bg-secondary);
  padding: 24px;
  border-radius: 8px;
}

.tech-item h3 {
  color: var(--primary);
  margin-bottom: 8px;
}

/* Projects */
.projects-preview {
  margin-top: 24px;
}

.btn {
  display: inline-block;
  background: var(--primary);
  color: white;
  padding: 12px 24px;
  border-radius: 6px;
  font-weight: 500;
  transition: background 0.2s;
}

.btn:hover {
  background: #1d4ed8;
  text-decoration: none;
}

.project-card {
  background: var(--bg-secondary);
  padding: 24px;
  border-radius: 8px;
  margin-bottom: 24px;
}

.project-card h3 {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

.project-desc {
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.project-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.project-tags span {
  background: #dbeafe;
  color: #1e40af;
  padding: 4px 12px;
  border-radius: 16px;
  font-size: 0.875rem;
}

.project-links {
  display: flex;
  gap: 16px;
}

/* Contact */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
}

.contact-card {
  background: var(--bg-secondary);
  padding: 24px;
  border-radius: 8px;
  text-align: center;
}

.contact-card h3 {
  color: var(--primary);
  margin-bottom: 12px;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
  color: var(--text-secondary);
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
}

.beian {
  margin-top: 8px;
}

.beian a {
  color: var(--text-secondary);
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }
  
  .nav-links {
    gap: 16px;
  }
}