:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f6f7f9;
  --color-text: #1a1d23;
  --color-text-muted: #5b6270;
  --color-border: #e4e6ea;
  --color-accent: #2f6feb;
  --color-accent-contrast: #ffffff;
  --max-width: 1080px;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 8px 24px rgba(0, 0, 0, 0.04);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Microsoft JhengHei", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}

section[id] {
  scroll-margin-top: 72px;
}

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

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Header / Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--color-border);
}

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

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

.site-nav {
  display: flex;
  align-items: center;
  gap: 24px;
}

.site-nav a {
  color: var(--color-text);
  font-size: 0.95rem;
}

.lang-toggle {
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  border-radius: 999px;
  padding: 6px 14px;
  font-size: 0.85rem;
  cursor: pointer;
}

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

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
}

/* Hero */
.hero {
  padding: 96px 0 72px;
  text-align: center;
}

.avatar-placeholder {
  width: 96px;
  height: 96px;
  margin: 0 auto 24px;
  border-radius: 50%;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
}

.hero-greeting {
  margin: 0 0 8px;
  color: var(--color-text-muted);
  font-size: 1rem;
}

.hero-name {
  margin: 0 0 16px;
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
}

.hero-tagline {
  max-width: 560px;
  margin: 0 auto 32px;
  color: var(--color-text-muted);
  font-size: 1.05rem;
}

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

.btn {
  display: inline-block;
  padding: 12px 24px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  border: 1px solid transparent;
}

.btn:hover { text-decoration: none; }

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

.btn-primary:hover { opacity: 0.9; }

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

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

/* Sections */
.section {
  padding: 72px 0;
}

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

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 0 0 8px;
}

.section-subtitle {
  color: var(--color-text-muted);
  margin: 0 0 32px;
}

.about-body {
  max-width: 680px;
  color: var(--color-text-muted);
}

.skills-title {
  margin-top: 32px;
  font-size: 1.1rem;
}

.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  list-style: none;
  padding: 0;
  margin: 12px 0 0;
}

.skills-list li {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 6px 16px;
  font-size: 0.9rem;
}

/* Projects */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.project-thumb {
  height: 140px;
  border-radius: 8px;
  margin-bottom: 16px;
  background: linear-gradient(135deg, var(--color-bg-alt), var(--color-border));
}

.project-tag {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--color-accent);
  background: rgba(47, 111, 235, 0.1);
  border-radius: 999px;
  padding: 3px 10px;
  margin-bottom: 10px;
}

.project-card h3 {
  margin: 0 0 8px;
  font-size: 1.15rem;
}

.project-card p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin: 0 0 12px;
}

.project-link {
  font-size: 0.9rem;
  font-weight: 600;
}

/* Resume */
.resume-inner {
  text-align: center;
}

.resume-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
  margin: 24px 0 12px;
}

.resume-note {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* Contact */
.contact-inner {
  max-width: 640px;
}

.contact-list {
  display: grid;
  gap: 20px;
  margin: 24px 0;
}

.contact-list dt {
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.contact-list dd {
  margin: 4px 0 0;
}

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

.contact-note {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* Footer */
.site-footer {
  padding: 32px 0;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--color-border);
}

/* Mobile */
@media (max-width: 720px) {
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    align-items: flex-start;
    padding: 16px 24px 24px;
    gap: 16px;
    display: none;
  }

  .site-nav.open {
    display: flex;
  }

  .hero {
    padding: 72px 0 56px;
  }
}