/* ===== CSS Variables ===== */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-amazon: #ff9900;
  --color-text: #1f2937;
  --color-text-muted: #6b7280;
  --color-border: #e5e7eb;
  --color-bg: #ffffff;
  --color-bg-subtle: #f9fafb;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Hiragino Kaku Gothic ProN', 'Noto Sans JP', sans-serif;
  --max-width: 1100px;
  --radius: 8px;
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--font-sans); color: var(--color-text); background: var(--color-bg); line-height: 1.7; }
img { max-width: 100%; height: auto; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== Layout ===== */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1rem; }

/* ===== Header ===== */
.site-header { background: var(--color-bg); border-bottom: 1px solid var(--color-border); padding: 0.75rem 0; position: sticky; top: 0; z-index: 100; }
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap; }
.site-logo { font-size: 1.1rem; font-weight: 700; color: var(--color-text); }
.site-nav { display: flex; gap: 1.5rem; flex-wrap: wrap; }
.site-nav a { font-size: 0.9rem; color: var(--color-text-muted); }
.site-nav a.active, .site-nav a:hover { color: var(--color-primary); }

/* ===== Main ===== */
.site-main { padding: 2rem 0 4rem; min-height: 60vh; }

/* ===== Footer ===== */
.site-footer { background: var(--color-bg-subtle); border-top: 1px solid var(--color-border); padding: 2rem 0; margin-top: 4rem; font-size: 0.85rem; color: var(--color-text-muted); }
.footer-nav { display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: 1rem; }
.affiliate-notice { margin-bottom: 0.5rem; }

/* ===== Breadcrumbs ===== */
.breadcrumbs { margin-bottom: 1.5rem; }
.breadcrumbs ol { display: flex; flex-wrap: wrap; gap: 0.25rem; list-style: none; font-size: 0.85rem; color: var(--color-text-muted); }
.breadcrumbs .sep { color: var(--color-border); }

/* ===== Hero ===== */
.hero { text-align: center; padding: 3rem 1rem; background: var(--color-bg-subtle); border-radius: var(--radius); margin-bottom: 3rem; }
.hero h1 { font-size: 2rem; margin-bottom: 0.75rem; }
.hero p { color: var(--color-text-muted); font-size: 1.1rem; }

/* ===== Category Grid ===== */
.categories { margin-bottom: 3rem; }
.categories h2 { font-size: 1.4rem; margin-bottom: 1rem; }
.category-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1rem; }
.category-card { display: block; padding: 1.5rem; border: 1px solid var(--color-border); border-radius: var(--radius); transition: border-color 0.2s; }
.category-card:hover { border-color: var(--color-primary); text-decoration: none; }
.category-card h3 { font-size: 1.1rem; margin-bottom: 0.5rem; color: var(--color-text); }
.category-card p { font-size: 0.9rem; color: var(--color-text-muted); }

/* ===== Item Grid ===== */
.item-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 1rem; margin-bottom: 1rem; }
.item-card { border: 1px solid var(--color-border); border-radius: var(--radius); overflow: hidden; display: flex; flex-direction: column; }
.item-card a { color: inherit; }
.item-card-img { aspect-ratio: 1; background: var(--color-bg-subtle); display: flex; align-items: center; justify-content: center; }
.item-card-img img { width: 100%; height: 100%; object-fit: contain; }
.no-image { color: var(--color-text-muted); font-size: 0.8rem; }
.item-card-body { padding: 0.75rem; flex: 1; }
.item-brand { font-size: 0.75rem; color: var(--color-text-muted); margin-bottom: 0.25rem; }
.item-name { font-size: 0.9rem; font-weight: 600; margin-bottom: 0.25rem; }
.item-price { font-size: 0.85rem; color: var(--color-text-muted); }

/* ===== Buttons ===== */
.btn { display: inline-block; padding: 0.6rem 1.2rem; border-radius: var(--radius); font-weight: 600; font-size: 0.9rem; text-align: center; transition: background 0.2s; }
.btn-amazon { background: var(--color-amazon); color: #fff; }
.btn-amazon:hover { background: #e88a00; text-decoration: none; color: #fff; }
.btn-more { background: var(--color-primary); color: #fff; margin-top: 1rem; }
.btn-more:hover { background: var(--color-primary-dark); text-decoration: none; color: #fff; }
.btn-large { padding: 0.875rem 2rem; font-size: 1rem; }

/* ===== Article ===== */
.article-header, .learn-header, .usecase-header, .page-header { margin-bottom: 2rem; }
.article-header h1, .learn-header h1, .usecase-header h1, .page-header h1 { font-size: 1.75rem; line-height: 1.4; margin-bottom: 0.5rem; }
.updated-at { font-size: 0.85rem; color: var(--color-text-muted); display: block; margin-bottom: 0.5rem; }
.affiliate-disclosure { font-size: 0.8rem; color: var(--color-text-muted); padding: 0.5rem; background: var(--color-bg-subtle); border-left: 3px solid var(--color-border); margin-bottom: 1rem; }

.article-body h2 { font-size: 1.3rem; margin: 2rem 0 0.75rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--color-border); }
.article-body h3 { font-size: 1.1rem; margin: 1.5rem 0 0.5rem; }
.article-body p { margin-bottom: 1rem; }
.article-body ul, .article-body ol { margin: 0.5rem 0 1rem 1.5rem; }
.article-body li { margin-bottom: 0.25rem; }
.article-body table { width: 100%; border-collapse: collapse; margin: 1rem 0; }
.article-body th, .article-body td { padding: 0.6rem 0.75rem; border: 1px solid var(--color-border); text-align: left; }
.article-body th { background: var(--color-bg-subtle); font-weight: 600; }

/* ===== Item Page ===== */
.item-page .item-header { margin-bottom: 1.5rem; }
.item-brand-label { font-size: 0.85rem; color: var(--color-text-muted); margin-bottom: 0.25rem; }
.item-price-range { font-size: 1rem; color: var(--color-primary); font-weight: 600; margin-top: 0.25rem; }
.cta-top, .cta-bottom { margin: 1.5rem 0; padding: 1.5rem; background: var(--color-bg-subtle); border-radius: var(--radius); text-align: center; }
.item-main-image { margin: 1.5rem 0; max-width: 400px; }
.spec-table { width: 100%; border-collapse: collapse; margin: 0.5rem 0; }
.spec-table th { background: var(--color-bg-subtle); padding: 0.5rem 0.75rem; border: 1px solid var(--color-border); text-align: left; width: 40%; }
.spec-table td { padding: 0.5rem 0.75rem; border: 1px solid var(--color-border); }
.item-features ul, .item-suitable ul { list-style: disc; margin-left: 1.5rem; }
.item-features li, .item-suitable li { margin-bottom: 0.25rem; }

/* ===== Article List ===== */
.article-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1rem; }
.article-card { border: 1px solid var(--color-border); border-radius: var(--radius); overflow: hidden; }
.article-card a { display: block; padding: 1rem; color: inherit; }
.article-card h3 { font-size: 1rem; margin-bottom: 0.4rem; }
.article-card p { font-size: 0.85rem; color: var(--color-text-muted); margin-bottom: 0.4rem; }
.article-card time { font-size: 0.75rem; color: var(--color-text-muted); }
.article-card:hover { border-color: var(--color-primary); }

/* ===== Sections ===== */
.featured-items, .recent-articles, .article-section, .item-section, .related-items, .cta-section, .related-articles, .related-items-section { margin-top: 3rem; }
.featured-items h2, .recent-articles h2, .article-section h2, .item-section h2, .related-items h2, .cta-section h2, .related-articles h2, .related-items-section h2 { font-size: 1.3rem; margin-bottom: 1rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--color-border); }

/* ===== Responsive ===== */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.5rem; }
  .site-nav { gap: 0.75rem; }
  .item-grid { grid-template-columns: repeat(2, 1fr); }
  .article-list { grid-template-columns: 1fr; }
}

/* ===== Related Articles Cards ===== */
.related-articles .article-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1rem; margin-top: 1rem; }
.related-articles .article-card { border: 1px solid var(--color-border); border-radius: var(--radius); padding: 1rem; transition: all 0.2s; }
.related-articles .article-card:hover { border-color: var(--color-primary); box-shadow: 0 2px 8px rgba(0,0,0,0.1); }
.related-articles .article-card h3 { font-size: 1rem; margin-bottom: 0.5rem; line-height: 1.4; }
.related-articles .article-card h3 a { color: var(--color-text); }
.related-articles .article-card h3 a:hover { color: var(--color-primary); text-decoration: none; }
.related-articles .article-card p { font-size: 0.85rem; color: var(--color-text-muted); margin-bottom: 0.5rem; line-height: 1.5; }
.related-articles .article-card time { font-size: 0.75rem; color: var(--color-text-muted); display: block; }