:root {
    --bt-bg: #09090b;
    --bt-card: #18181b;
    --bt-card-hover: #27272a;
    --bt-border: #3f3f46;
    --bt-text: #f4f4f5;
    --bt-muted: #a1a1aa;
    --bt-cyan: #06b6d4;
    --bt-cyan-dark: #0891b2;
    --bt-purple: #a855f7;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, "Pretendard", "Segoe UI", sans-serif; background: var(--bt-bg); color: var(--bt-text); line-height: 1.6; overflow-x: hidden; }
a { text-decoration: none; color: inherit; }

/* Header */
.bt-header { background: rgba(9, 9, 11, 0.8); backdrop-filter: blur(12px); border-bottom: 1px solid var(--bt-border); position: sticky; top: 0; z-index: 100; }
.bt-header-inner { max-width: 1280px; margin: 0 auto; padding: 16px 24px; display: flex; justify-content: space-between; align-items: center; }
.bt-logo { display: flex; align-items: center; gap: 8px; font-weight: 900; font-size: 1.3rem; letter-spacing: 1px; color: #fff; }
.bt-logo-icon { width: 12px; height: 12px; background: var(--bt-cyan); border-radius: 50%; box-shadow: 0 0 10px var(--bt-cyan); }
.bt-nav { display: flex; gap: 24px; font-size: 0.95rem; font-weight: 600; color: var(--bt-muted); }
.bt-nav a:hover { color: var(--bt-cyan); }

.bt-container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }

/* Hero Minimalist */
.bt-hero { padding: 60px 0 40px 0; max-width: 900px; }
.bt-badge { display: inline-block; border: 1px solid var(--bt-cyan); color: var(--bt-cyan); padding: 4px 12px; border-radius: 20px; font-size: 0.75rem; font-weight: 800; margin-bottom: 16px; letter-spacing: 1px; background: rgba(6, 182, 212, 0.1); }
.bt-hero h1 { font-size: 2.4rem; font-weight: 900; line-height: 1.3; margin-bottom: 16px; letter-spacing: -1px; color: #fff; }
.bt-hero p { font-size: 1.05rem; color: var(--bt-muted); line-height: 1.6; max-width: 700px; }

/* 🌟 BENTO BOX GRID LAYOUT (1~4위 동등 부각 4등분 그리드) 🌟 */
.bt-bento-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin-bottom: 60px; }
.bt-bento-tile { background: var(--bt-card); border: 1px solid var(--bt-border); border-radius: 24px; padding: 24px; transition: transform 0.2s, background 0.2s, border-color 0.2s; position: relative; overflow: hidden; display: flex; flex-direction: column; cursor: pointer; }
.bt-bento-tile:hover { transform: translateY(-4px); background: var(--bt-card-hover); border-color: var(--bt-cyan); box-shadow: 0 8px 24px rgba(6, 182, 212, 0.1); }

/* Tile Span Rules */
/* 1위~4위는 모두 가로 2칸 와이드 타일로 동등하게 4등분 배치 */
.bento-prime { grid-column: span 2; grid-row: span 1; padding: 30px; background: linear-gradient(145deg, #18181b 0%, #1e1e24 100%); border: 1px solid #3f3f46; }
/* 5위 이하는 1칸 정방형 미니 타일 */
.bento-square { grid-column: span 1; grid-row: span 1; justify-content: space-between; }

/* Tile Inner Elements */
.bt-tile-rank { font-size: 3.5rem; font-weight: 900; color: rgba(255,255,255,0.05); position: absolute; top: -10px; right: 10px; line-height: 1; }
.bento-prime .bt-tile-rank { font-size: 6rem; right: -10px; top: -20px; color: rgba(6, 182, 212, 0.05); }

.bt-tile-header { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 16px; position: relative; z-index: 2; }
.bt-tile-logo { background: #fff; padding: 8px; border-radius: 8px; display: inline-flex; align-items: center; justify-content: center; }
.bento-square .bt-tile-logo { width: 60px; height: 30px; }
.bento-prime .bt-tile-logo { width: 100px; height: 45px; margin-bottom: 5px; }
.bt-tile-logo img { max-width: 100%; max-height: 100%; object-fit: contain; }

.bt-tile-rating { background: rgba(168, 85, 247, 0.15); color: #c084fc; font-size: 0.8rem; font-weight: 800; padding: 4px 10px; border-radius: 12px; }

.bt-tile-name { font-size: 1.25rem; font-weight: 900; color: #fff; margin-bottom: 6px; position: relative; z-index: 2; }
.bento-prime .bt-tile-name { font-size: 1.6rem; margin-bottom: 10px; color: var(--bt-cyan); } /* 1~4위 이름 강조 */

.bt-tile-desc { font-size: 0.9rem; color: var(--bt-muted); margin-bottom: 16px; line-height: 1.5; position: relative; z-index: 2; flex: 1; }
.bento-prime .bt-tile-desc { font-size: 1rem; }
.bento-square .bt-tile-desc { display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; font-size: 0.85rem; margin-bottom: 12px; } 

.bt-tile-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 16px; position: relative; z-index: 2; }
.bt-tag { background: #27272a; color: #d4d4d8; font-size: 0.75rem; padding: 4px 10px; border-radius: 6px; font-weight: 600; }
.bento-square .bt-tile-tags { display: none; } 

.bt-tile-footer { margin-top: auto; position: relative; z-index: 2; }
.bt-benefit-text { font-size: 1.05rem; font-weight: 900; color: var(--bt-cyan); display: block; margin-bottom: 10px; }
.bento-prime .bt-benefit-text { font-size: 1.15rem; margin-bottom: 16px; color: #fff; background: rgba(6, 182, 212, 0.2); padding: 6px 12px; border-radius: 8px; display: inline-block; }
.bento-square .bt-benefit-text { font-size: 0.95rem; margin-bottom: 8px; }

.bt-arrow-link { display: inline-flex; align-items: center; gap: 8px; color: #fff; font-size: 0.9rem; font-weight: 800; transition: color 0.2s; }
.bt-bento-tile:hover .bt-arrow-link { color: var(--bt-cyan); }
.bt-arrow-link::after { content: "→"; font-size: 1.1rem; transition: transform 0.2s; }
.bt-bento-tile:hover .bt-arrow-link::after { transform: translateX(5px); }

/* Text Content Block */
.bt-doc-block { background: var(--bt-card); border: 1px solid var(--bt-border); border-radius: 24px; padding: 40px; margin-bottom: 60px; }
.bt-doc-block h2 { font-size: 1.5rem; font-weight: 900; color: #fff; margin-bottom: 20px; }
.bt-doc-block h3 { font-size: 1.1rem; font-weight: 800; color: var(--bt-cyan); margin: 30px 0 12px 0; }
.bt-doc-block p { font-size: 1rem; color: var(--bt-muted); line-height: 1.8; margin-bottom: 16px; }
.bt-doc-block ul { padding-left: 20px; margin-bottom: 16px; }
.bt-doc-block li { font-size: 0.95rem; color: var(--bt-muted); line-height: 1.8; margin-bottom: 8px; }

/* Posts Masonry-like Grid */
.bt-sec-title { font-size: 1.5rem; font-weight: 900; color: #fff; margin-bottom: 24px; }
.bt-post-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-bottom: 60px; }
.bt-post-card { background: var(--bt-card); border: 1px solid var(--bt-border); border-radius: 16px; padding: 24px; display: flex; flex-direction: column; transition: border-color 0.2s; }
.bt-post-card:hover { border-color: var(--bt-purple); }
.bt-post-cat { color: var(--bt-purple); font-size: 0.75rem; font-weight: 800; margin-bottom: 10px; text-transform: uppercase; }
.bt-post-title { font-size: 1.1rem; font-weight: 800; color: #fff; margin-bottom: 10px; line-height: 1.4; }
.bt-post-summary { font-size: 0.9rem; color: var(--bt-muted); line-height: 1.6; margin-bottom: 20px; flex: 1; }
.bt-post-meta { font-size: 0.8rem; color: #52525b; border-top: 1px solid #27272a; padding-top: 12px; display: flex; justify-content: space-between; }

/* Footer */
.bt-footer { border-top: 1px solid var(--bt-border); padding: 60px 0 40px 0; margin-top: 40px; background: #000; }
.bt-footer-top { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 40px; margin-bottom: 40px; }
.bt-footer-brand p { color: var(--bt-muted); font-size: 0.9rem; max-width: 400px; line-height: 1.6; }
.bt-footer-links { display: flex; gap: 24px; flex-wrap: wrap; }
.bt-footer-links a { color: var(--bt-muted); font-size: 0.9rem; font-weight: 600; }
.bt-footer-links a:hover { color: #fff; }
.bt-legal-warn { background: rgba(239, 68, 68, 0.1); border: 1px solid rgba(239, 68, 68, 0.2); padding: 16px 20px; border-radius: 12px; color: #fca5a5; font-size: 0.85rem; line-height: 1.6; margin-bottom: 30px; }
.bt-footer-bottom { display: flex; justify-content: space-between; color: #52525b; font-size: 0.85rem; border-top: 1px solid #27272a; padding-top: 20px; flex-wrap: wrap; gap: 10px; }

/* Responsive Media Queries */
@media (max-width: 1024px) {
    .bt-bento-grid { grid-template-columns: repeat(2, 1fr); }
    .bento-prime { grid-column: span 2; }
    .bento-square { grid-column: span 1; }
    .bt-post-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
    .bt-nav { display: none; }
    .bt-hero { padding: 30px 0 20px 0; }
    .bt-hero h1 { font-size: 1.6rem; margin-bottom: 10px; }
    .bt-hero p { font-size: 0.9rem; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
    
    .bt-bento-grid { grid-template-columns: 1fr; gap: 16px; margin-bottom: 40px; }
    /* 모바일에서는 모두 1열 구조로 변환 */
    .bento-prime, .bento-square { grid-column: span 1; grid-row: auto; padding: 20px; }
    .bento-prime .bt-tile-name { font-size: 1.3rem; }
    .bento-prime .bt-tile-desc { font-size: 0.9rem; }
    
    .bt-post-grid { grid-template-columns: 1fr; }
    .bt-doc-block { padding: 24px; }
}