:root {
    --primary: #f26d21;
    --bg-dark: #121212;
    --bg-card: #1e1e1e;
    --text-main: #f5f5f5;
    --text-muted: #aaaaaa;
    --border-color: #333;
}
body {
    margin: 0;
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Meiryo', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    overflow-x: hidden;
}
/* ヘッダー（上部固定） */
header {
    background-color: rgba(0, 0, 0, 0.95);
    padding: 1rem 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid var(--primary);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(5px);
}
.logo { font-size: 1.5rem; font-weight: bold; color: #fff; text-decoration: none; letter-spacing: 1px; }
.logo span { color: var(--primary); }
.nav-links a { color: #fff; text-decoration: none; margin-left: 1.5rem; font-size: 0.9rem; }
.hamburger { color: #fff; font-size: 1.5rem; cursor: pointer; display: none; }

/* サイドメニュー（PC時は左固定、SP時はハンバーガー） */
.overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.7); z-index: 1001; display: none; opacity: 0; transition: 0.3s; }
.overlay.active { display: block; opacity: 1; }

/* Desktop: 左サイドバー固定 (Headerの下から100vh) */
.side-menu { 
    position: fixed; 
    top: 66px; /* Headerの高さ分 */
    left: 0; 
    width: 280px; 
    height: calc(100vh - 66px); 
    background-color: #121212; 
    z-index: 900; 
    display: flex; 
    flex-direction: column; 
    border-right: 1px solid var(--border-color);
}
.main-wrapper {
    margin-left: 280px; /* サイドバーの幅だけ右にずらす */
}
.mobile-only-btn { display: none; }
.menu-header { display: none; /* PCではMENUヘッダー不要 */ }

.menu-content { padding: 20px; overflow-y: auto; flex: 1; padding-bottom: 100px; }
.menu-section { margin-bottom: 30px; }
.menu-section h3 { color: var(--text-muted); font-size: 0.9rem; margin-bottom: 15px; border-bottom: 1px solid var(--border-color); padding-bottom: 5px; }
.menu-link { display: block; color: var(--text-main); text-decoration: none; padding: 10px 0; border-bottom: 1px solid #2a2a2a; transition: 0.2s; }
.menu-link:hover { color: var(--primary); padding-left: 5px; }

/* アコーディオンUI（絞り込み用） */
.accordion, .sub-accordion { background: none; color: #fff; cursor: pointer; padding: 15px 0; width: 100%; text-align: left; border: none; border-bottom: 1px solid #2a2a2a; outline: none; font-size: 1rem; display: flex; justify-content: space-between; align-items: center; font-weight: bold; }
.sub-accordion { font-size: 0.9rem; font-weight: normal; color: #ddd; padding: 12px 10px; border-bottom: 1px dashed #333; }
.accordion.active, .sub-accordion.active, .accordion:hover, .sub-accordion:hover { color: var(--primary); }
.panel, .sub-panel { padding: 0 10px; display: none; background-color: #151515; overflow: hidden; }
.panel.show, .sub-panel.show { display: block; }
.filter-group { margin: 15px 0; }
.filter-group h4 { margin: 0 0 10px 0; font-size: 0.8rem; color: var(--primary); }
.sub-panel label { display: block; padding: 8px 0; font-size: 0.85rem; color: #ccc; cursor: pointer; }
.sub-panel label:hover { color: #fff; }
.sub-panel input[type="checkbox"] { margin-right: 8px; accent-color: var(--primary); }
.badge { background: #333; color: #aaa; font-size: 0.6rem; padding: 3px 6px; border-radius: 4px; vertical-align: middle; margin-left: 5px; }
.filter-action { position: absolute; bottom: 0; left: 0; width: 100%; padding: 20px; background: #111; border-top: 1px solid var(--border-color); box-sizing: border-box; }
.btn-primary { width: 100%; background: var(--primary); color: #fff; border: none; padding: 15px; font-size: 1rem; font-weight: bold; border-radius: 4px; cursor: pointer; }
.btn-primary:hover { background: #e05e19; }

/* ヒーロー＆メイン */
.hero { background: linear-gradient(rgba(0,0,0,0.7), rgba(0,0,0,0.7)), url('https://images.unsplash.com/photo-1558981403-c5f9899a28bc?q=80&w=1920&auto=format&fit=crop') center/cover; padding: 100px 5%; text-align: center; }
.hero h1 { font-size: 2.5rem; margin-bottom: 10px; }
.hero p { font-size: 1.1rem; color: var(--text-muted); margin-bottom: 30px; }
.search-box { background: rgba(255,255,255,0.1); padding: 20px; border-radius: 8px; max-width: 600px; margin: 0 auto; backdrop-filter: blur(10px); display: flex; gap: 10px; }
.search-box input { flex: 1; padding: 12px; border: none; border-radius: 4px; font-size: 1rem; }
.search-box button { background-color: var(--primary); color: #fff; border: none; padding: 12px 24px; border-radius: 4px; font-size: 1rem; font-weight: bold; cursor: pointer; }
.btn-outline-light { background: transparent; border: 1px solid rgba(255,255,255,0.3); color: #fff; padding: 8px 20px; border-radius: 20px; cursor: pointer; transition: 0.3s; }
.btn-outline-light:hover { background: rgba(255,255,255,0.1); border-color: #fff; }

/* グリッド等 */
.container { padding: 50px 5%; max-width: 1200px; margin: 0 auto; }
.section-title { border-left: 4px solid var(--primary); padding-left: 10px; font-size: 1.5rem; margin-bottom: 30px; }

/* SEO Links Block */
.seo-links { display: flex; flex-wrap: wrap; gap: 30px; margin-top: 20px; background: var(--bg-card); padding: 30px; border-radius: 8px; }
.seo-link-group { flex: 1; min-width: 200px; }
.seo-link-group h4 { color: var(--primary); margin-top: 0; margin-bottom: 15px; font-size: 1.1rem; border-bottom: 1px solid var(--border-color); padding-bottom: 10px; }
.seo-link-group a { display: block; color: var(--text-muted); text-decoration: none; margin-bottom: 12px; font-size: 0.95rem; transition: 0.2s; }
.seo-link-group a i { font-size: 0.8rem; margin-right: 5px; color: #555; }
.seo-link-group a:hover { color: #fff; padding-left: 5px; }
.seo-link-group a:hover i { color: var(--primary); }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; }
.card { background-color: var(--bg-card); border-radius: 8px; overflow: hidden; transition: transform 0.2s; }
.card:hover { transform: translateY(-5px); box-shadow: 0 5px 15px rgba(0,0,0,0.5); }
.card img { width: 100%; height: 200px; object-fit: cover; }
.card-body { padding: 15px; }
.bike-title { font-size: 1.2rem; font-weight: bold; margin: 0 0 10px 0; }
.bike-price { color: var(--primary); font-size: 1.4rem; font-weight: bold; margin-bottom: 10px; }
.bike-details { color: var(--text-muted); font-size: 0.85rem; margin-bottom: 10px; display: flex; justify-content: space-between;}
.shop-name { font-size: 0.8rem; background: #333; padding: 5px; border-radius: 4px; display: inline-block; color: #ccc;}
footer { background-color: #050505; padding: 40px 5%; margin-top: 50px; text-align: center; border-top: 1px solid var(--border-color); }
.b2b-box { background-color: #1a1a1a; padding: 30px; border-radius: 8px; max-width: 800px; margin: 0 auto 30px; border: 1px solid var(--border-color); }
.b2b-box h3 { color: var(--primary); margin-top: 0;}
.btn-outline { display: inline-block; padding: 10px 20px; border: 1px solid var(--text-muted); color: var(--text-main); text-decoration: none; border-radius: 4px; margin: 5px; font-size: 0.9rem; transition: 0.2s;}
.btn-outline:hover { background: #333; }
.copyright { color: #666; font-size: 0.8rem; }

/* スマホ時 (Mobile) */
@media (max-width: 768px) {
    .nav-links { display: none; }
    .hamburger { display: block; }
    .hero h1 { font-size: 1.8rem; }
    .search-box { flex-direction: column; }
    .seo-links { flex-direction: column; gap: 20px; }
    
    /* SP用ハンバーガーメニューの挙動 */
    .main-wrapper { margin-left: 0; }
    .mobile-only-btn { display: block; }
    .side-menu { 
        position: fixed; 
        top: 0; 
        left: -350px; /* 左からスライドイン */
        width: 85%; 
        max-width: 350px; 
        height: 100vh; 
        background-color: #1a1a1a; 
        z-index: 1002; 
        transition: left 0.3s ease; 
        border-right: none;
        box-shadow: 5px 0 15px rgba(0,0,0,0.5);
    }
    .side-menu.active { left: 0; }
    .menu-header { 
        display: flex; 
        padding: 20px; 
        justify-content: space-between; 
        align-items: center; 
        border-bottom: 1px solid var(--border-color); 
        background: #111; 
    }
    .close-btn { font-size: 1.5rem; cursor: pointer; color: var(--text-muted); transition: 0.2s; }
}