/* =========================================================
   Theme tokens
   テーマ追加は [data-theme="..."] を増やすだけ。
   ========================================================= */
:root {
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI",
    "Hiragino Kaku Gothic ProN", "Yu Gothic UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", "Consolas", "Liberation Mono", monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;

  --container-max: 720px;

  --transition: 160ms ease;
}

/* Light theme (default) */
:root,
[data-theme="light"] {
  --bg: #fafafa;
  --bg-elev: #ffffff;
  --fg: #1a1a1a;
  --fg-muted: #5a5a5a;
  --border: #e4e4e4;
  --accent: #2563eb;
  --accent-fg: #ffffff;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 2px 6px rgba(0, 0, 0, 0.04);
}

/* Dark theme */
[data-theme="dark"] {
  --bg: #111214;
  --bg-elev: #1a1c1f;
  --fg: #e8e8e8;
  --fg-muted: #9aa0a6;
  --border: #2a2d31;
  --accent: #7aa2ff;
  --accent-fg: #0b1020;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 2px 8px rgba(0, 0, 0, 0.35);
}

/* =========================================================
   Reset / base
   ========================================================= */
*, *::before, *::after { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

html {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  transition: background var(--transition), color var(--transition);
}

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

h1, h2, h3 { line-height: 1.25; margin: 0 0 var(--space-4); }
h1 { font-size: 1.875rem; }
h2 { font-size: 1.375rem; }
h3 { font-size: 1.05rem; }

p { margin: 0 0 var(--space-4); }

code, pre { font-family: var(--font-mono); }

/* =========================================================
   Layout
   ========================================================= */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

main.container {
  flex: 1;
  padding-top: var(--space-8);
  padding-bottom: var(--space-12);
}

/* =========================================================
   Header
   ========================================================= */
.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: saturate(180%) blur(6px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.site-title {
  color: var(--fg);
  font-weight: 600;
  letter-spacing: 0.02em;
}
.site-title:hover { text-decoration: none; color: var(--accent); }

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.site-nav a {
  color: var(--fg-muted);
  font-size: 0.9rem;
}
.site-nav a:hover { color: var(--fg); text-decoration: none; }

.theme-toggle {
  background: transparent;
  color: var(--fg-muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.25rem 0.6rem;
  font-size: 0.8rem;
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition), background var(--transition);
}
.theme-toggle:hover {
  color: var(--fg);
  border-color: var(--fg-muted);
}

/* =========================================================
   Intro
   ========================================================= */
.intro {
  margin-bottom: var(--space-12);
}
.intro p {
  color: var(--fg-muted);
  max-width: 60ch;
}

.section-title {
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: var(--space-4);
}

/* =========================================================
   Project grid
   ========================================================= */
.project-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-4);
}

.project-card {
  display: block;
  padding: var(--space-6);
  background: var(--bg-elev);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow);
  transition: transform var(--transition), border-color var(--transition);
}
.project-card:hover {
  text-decoration: none;
  transform: translateY(-1px);
  border-color: var(--fg-muted);
}

.project-name {
  margin: 0 0 var(--space-2);
  color: var(--fg);
}
.project-desc {
  margin: 0 0 var(--space-3);
  color: var(--fg-muted);
  font-size: 0.95rem;
}
.project-meta {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--fg-muted);
}

/* =========================================================
   Project detail page
   ========================================================= */
.back-link {
  display: inline-block;
  margin-bottom: var(--space-6);
  font-size: 0.9rem;
  color: var(--fg-muted);
}
.back-link:hover { color: var(--fg); text-decoration: none; }

.project-detail h1 { margin-bottom: var(--space-2); }
.project-tagline {
  color: var(--fg-muted);
  margin-bottom: var(--space-8);
}

.project-section {
  margin-bottom: var(--space-8);
}

.link-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}
.link-list a {
  display: inline-block;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
}
.link-list a:hover {
  text-decoration: none;
  border-color: var(--accent);
}

/* =========================================================
   Footer
   ========================================================= */
.site-footer {
  border-top: 1px solid var(--border);
  padding: var(--space-6) 0;
  color: var(--fg-muted);
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-3);
}
.footer-nav { display: flex; gap: var(--space-4); }
.footer-nav a { color: var(--fg-muted); font-size: 0.85rem; }
.footer-nav a:hover { color: var(--fg); text-decoration: none; }

/* =========================================================
   Responsive
   ========================================================= */
@media (max-width: 480px) {
  h1 { font-size: 1.5rem; }
  .header-inner { height: 52px; }
  .theme-toggle-label { display: none; }
  .theme-toggle::before { content: "◐"; }
}