:root {
  --bg: #ffffff;
  --bg-alt: #f5f6f8;
  --text: #1a1d21;
  --text-muted: #55606b;
  --accent: #2f6fed;
  --accent-text: #ffffff;
  --border: #e2e5e9;
  --card-bg: #ffffff;
  --tag-bg: #eef2ff;
  --tag-text: #2f4fb0;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161a;
    --bg-alt: #1b1e23;
    --text: #edeff2;
    --text-muted: #a3acb8;
    --accent: #5b8dff;
    --accent-text: #0c1220;
    --border: #2a2e35;
    --card-bg: #1b1e23;
    --tag-bg: #202a45;
    --tag-text: #a9c0ff;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Hiragino Sans", "Yu Gothic UI", "Segoe UI", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}

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

.site-header {
  position: sticky;
  top: 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  z-index: 10;
}

.nav {
  max-width: 960px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-weight: 700;
  letter-spacing: 0.02em;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.4rem;
  color: var(--text);
  cursor: pointer;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

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

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

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.hero {
  padding: 5rem 0 4rem;
  text-align: center;
}

.hero h1 {
  font-size: 2.2rem;
  margin-bottom: 0.75rem;
}

.hero-name {
  display: block;
  font-size: 1.1rem;
  font-weight: 400;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

.hero-tagline {
  max-width: 40rem;
  margin: 0 auto 2rem;
  color: var(--text-muted);
  font-size: 1.05rem;
}

.hero-links {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 0.7rem 1.4rem;
  border-radius: 8px;
  font-weight: 600;
  border: 1px solid transparent;
}

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

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

.section {
  padding: 3.5rem 0;
  border-top: 1px solid var(--border);
}

.section h2 {
  font-size: 1.6rem;
  margin-bottom: 1.5rem;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.tag {
  background: var(--tag-bg);
  color: var(--tag-text);
  padding: 0.35rem 0.8rem;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
}

.tag--sm {
  font-size: 0.8rem;
  padding: 0.25rem 0.65rem;
}

.project-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
  margin-bottom: 1.75rem;
}

.project-card--featured {
  border-color: var(--accent);
}

.project-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.project-header h3 {
  margin: 0;
  font-size: 1.25rem;
}

.project-badge {
  background: var(--accent);
  color: var(--accent-text);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.15rem 0.6rem;
  border-radius: 999px;
}

.project-summary {
  color: var(--text-muted);
}

.project-points {
  margin: 1rem 0;
  padding-left: 1.2rem;
}

.project-points li {
  margin-bottom: 0.4rem;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
}

.project-link {
  font-weight: 600;
}

.site-footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--text-muted);
  font-size: 0.9rem;
}

@media (max-width: 640px) {
  .nav-toggle {
    display: block;
  }

  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    display: none;
    padding: 0.5rem 1.5rem 1rem;
  }

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

  .nav-links li {
    padding: 0.6rem 0;
  }

  .hero {
    padding: 3rem 0 2.5rem;
  }

  .hero h1 {
    font-size: 1.7rem;
  }
}