/* ===== テーマ変数 ===== */
:root {
  --bg: #f4f4f6;
  --bg2: #ffffff;
  --text: #1a1a2e;
  --text-muted: #666;
  --border: rgba(0,0,0,0.1);
  --card-bg: #ffffff;
  --card-shadow: 0 2px 16px rgba(0,0,0,0.08);
  --nav-bg: #ffffff;
  --nav-border: rgba(0,0,0,0.08);
  --drawer-bg: #f8f8fa;
  --code-bg: #f0f0f2;
  --link: #5b6af0;
  --btn: #5b6af0;
  --placeholder-bg: #e0e0e4;
}

[data-theme="dark"] {
  --bg: #111318;
  --bg2: #1a1d26;
  --text: #e8e8f0;
  --text-muted: #888;
  --border: rgba(255,255,255,0.08);
  --card-bg: #1e2130;
  --card-shadow: 0 2px 16px rgba(0,0,0,0.4);
  --nav-bg: #15171f;
  --nav-border: rgba(255,255,255,0.07);
  --drawer-bg: #13151e;
  --code-bg: #252836;
  --link: #7c8fff;
  --btn: #5b6af0;
  --placeholder-bg: #252836;
}

@media (prefers-color-scheme: dark) {
  [data-theme="auto"] {
    --bg: #111318;
    --bg2: #1a1d26;
    --text: #e8e8f0;
    --text-muted: #888;
    --border: rgba(255,255,255,0.08);
    --card-bg: #1e2130;
    --card-shadow: 0 2px 16px rgba(0,0,0,0.4);
    --nav-bg: #15171f;
    --nav-border: rgba(255,255,255,0.07);
    --drawer-bg: #13151e;
    --code-bg: #252836;
    --link: #7c8fff;
    --btn: #5b6af0;
    --placeholder-bg: #252836;
  }
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans JP', sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background 0.2s, color 0.2s;
}

/* ===== ドロワー ===== */
.drawer-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.35);
  z-index: 150;
}
.drawer-overlay.open { display: block; }

.drawer {
  position: fixed;
  top: 0;
  left: -280px;
  width: 260px;
  height: 100vh;
  background: var(--drawer-bg);
  border-right: 1px solid var(--border);
  transition: left 0.25s ease;
  z-index: 200;
  padding: 1.5rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  overflow-y: auto;
}
.drawer.open { left: 0; }

.drawer h2 {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin: 1rem 0 0.5rem 0;
  padding: 0 0.5rem;
}
.drawer h2:first-child { margin-top: 0; }

.drawer a {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 0.5rem;
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  border-radius: 6px;
  opacity: 0.85;
  transition: background 0.15s;
}
.drawer a:hover { background: var(--border); opacity: 1; }

.drawer-divider {
  border-top: 1px solid var(--border);
  margin: 0.75rem 0;
}

.theme-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 0.5rem;
  color: var(--text);
  background: none;
  border: none;
  font-size: 0.9rem;
  border-radius: 6px;
  opacity: 0.75;
  cursor: pointer;
  width: 100%;
  text-align: left;
  transition: background 0.15s, opacity 0.15s;
}
.theme-btn:hover { background: var(--border); opacity: 1; }
.theme-btn.active { opacity: 1; font-weight: 600; }

/* ===== ナビバー ===== */
.topbar {
  background: var(--nav-bg);
  border-bottom: 1px solid var(--nav-border);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0 1.5rem;
  height: 56px;
  position: sticky;
  top: 0;
  z-index: 100;
  flex-shrink: 0;
}

.site-logo {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  text-decoration: none;
}

.hamburger {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.4rem;
  display: flex;
  flex-direction: column;
  gap: 5px;
  opacity: 0.6;
  flex-shrink: 0;
}
.hamburger:hover { opacity: 1; }
.hamburger span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
}

/* ===== メインコンテンツ ===== */
.main-content {
  flex: 1;
  max-width: 860px;
  width: 100%;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

.page-header h1 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
}
.page-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* ===== ガイドセクション ===== */
/* テキスト左・画像右の横並び。画像を左にしたい場合は .guide-section.reverse を使う */
.guide-section {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 2rem;
  box-shadow: var(--card-shadow);
}
.guide-section.reverse {
  flex-direction: row-reverse;
}

.guide-text {
  flex: 1;
}
.guide-text h2 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}
.guide-steps {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
}
.guide-steps p::before {
  content: "・";
  opacity: 0.5;
}

code {
  background: var(--code-bg);
  padding: 0.1em 0.4em;
  border-radius: 4px;
  font-size: 0.85em;
  color: var(--link);
}

.guide-image {
  flex: 1;
  position: relative;
}
.guide-image img {
  width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border);
  display: block;
}
.image-placeholder {
  display: none;
  width: 100%;
  aspect-ratio: 16/9;
  background: var(--placeholder-bg);
  border-radius: 8px;
  border: 1px dashed var(--border);
  align-items: center;
  justify-content: center;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.8;
}
.guide-image.no-image img { display: none; }
.guide-image.no-image .image-placeholder { display: flex; }

/* ===== フッター ===== */
.site-footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.72rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  opacity: 0.6;
}
.site-footer a { color: inherit; }

/* ===== モバイル ===== */
@media (max-width: 640px) {
  .guide-section {
    flex-direction: column !important;
    padding: 1.25rem;
  }
  .main-content { padding: 1.5rem 1rem; }
}