/* BTC Heatmap - Dark Crypto Theme v2 */
:root {
    --bg-primary: #0a0e17;
    --bg-secondary: #111827;
    --bg-card: #1a1f2e;
    --accent: #00ff88;
    --accent-dim: #00cc6a;
    --text-primary: #e5e7eb;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    --border: #1f2937;
    --gradient-1: linear-gradient(135deg, #00ff88 0%, #00b4d8 100%);
    --shadow: 0 4px 20px rgba(0,255,136,0.1);
    --radius: 12px;
    --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: var(--font-main);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header */
.header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    position: sticky; top: 0; z-index: 100;
}
.header-inner {
    display: flex; align-items: center; justify-content: space-between;
    padding: 15px 20px; max-width: 1200px; margin: 0 auto;
}
.logo { font-size: 1.5rem; font-weight: 800; text-decoration: none; color: var(--text-primary); }
.logo span { background: var(--gradient-1); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }

/* Lang Switcher */
.lang-switcher { position: relative; }
.lang-btn {
    background: var(--bg-card); color: var(--text-primary);
    border: 1px solid var(--border); padding: 8px 16px; border-radius: 8px;
    cursor: pointer; font-size: 0.875rem; display: flex; align-items: center; gap: 6px;
}
.lang-btn:hover { border-color: var(--accent); }
.lang-dropdown {
    display: none; position: absolute; top: 100%; right: 0; margin-top: 4px;
    background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px;
    min-width: 180px; z-index: 200; max-height: 300px; overflow-y: auto;
}
.lang-switcher:hover .lang-dropdown { display: block; }
.lang-dropdown a {
    display: block; padding: 10px 16px; color: var(--text-secondary);
    text-decoration: none; font-size: 0.875rem; border-bottom: 1px solid var(--border);
}
.lang-dropdown a:last-child { border-bottom: none; }
.lang-dropdown a:hover { background: var(--bg-secondary); color: var(--accent); }

/* Nav */
.nav { display: flex; gap: 8px; }
.nav a {
    color: var(--text-secondary); text-decoration: none;
    padding: 8px 16px; border-radius: 8px; font-size: 0.9rem; transition: all 0.2s;
}
.nav a:hover, .nav a.active { background: var(--bg-card); color: var(--accent); }
.mobile-menu-btn { display: none; background: none; border: none; color: var(--text-primary); font-size: 1.5rem; cursor: pointer; }

/* Hero */
.hero {
    text-align: center; padding: 80px 20px;
    background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}
.hero h1 { font-size: clamp(2rem, 5vw, 3.5rem); font-weight: 800; margin-bottom: 20px; }
.hero h1 span { background: var(--gradient-1); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero p { font-size: clamp(1rem, 2vw, 1.25rem); color: var(--text-secondary); max-width: 700px; margin: 0 auto 30px; }
.hero-cta {
    display: inline-block; background: var(--gradient-1); color: #000;
    padding: 14px 36px; border-radius: var(--radius); font-weight: 700; font-size: 1.1rem;
    text-decoration: none; transition: all 0.2s;
}
.hero-cta:hover { transform: translateY(-2px); box-shadow: 0 8px 30px rgba(0,255,136,0.3); }

/* Features */
.features { padding: 60px 0; }
.features h2 { text-align: center; font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: 40px; }
.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 24px; }
.feature-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: 16px; padding: 30px; transition: all 0.3s;
}
.feature-card:hover { border-color: var(--accent); transform: translateY(-4px); box-shadow: var(--shadow); }
.feature-card .icon { font-size: 2.5rem; margin-bottom: 16px; }
.feature-card h3 { font-size: 1.2rem; font-weight: 700; margin-bottom: 10px; }
.feature-card p { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.7; }

/* Stats */
.stats { padding: 40px 0; }
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; }
.stat-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 24px; text-align: center;
}
.stat-card .number { font-size: 2rem; font-weight: 800; background: var(--gradient-1); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.stat-card .label { color: var(--text-secondary); font-size: 0.9rem; margin-top: 4px; }

/* Article Cards (Home + Category) */
.articles { padding: 60px 0; }
.articles h2 { text-align: center; font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: 40px; }
.articles-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); gap: 24px; }
.article-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: 16px; padding: 28px; transition: all 0.3s; display: flex; flex-direction: column;
}
.article-card:hover { border-color: var(--accent); transform: translateY(-4px); box-shadow: var(--shadow); }
.article-card .tag {
    display: inline-block; background: rgba(0,255,136,0.1); color: var(--accent);
    padding: 4px 12px; border-radius: 20px; font-size: 0.75rem; font-weight: 600; margin-bottom: 12px; align-self: flex-start;
}
.article-card h3 { font-size: 1.15rem; margin-bottom: 10px; flex: 1; }
.article-card h3 a { color: var(--text-primary); text-decoration: none; line-height: 1.4; display: block; }
.article-card h3 a:hover { color: var(--accent); }
.article-card p { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.7; }
.article-card .meta { color: var(--text-muted); font-size: 0.8rem; margin-top: 12px; }
.article-card .read-more {
    display: inline-block; color: var(--accent); text-decoration: none;
    font-weight: 600; font-size: 0.9rem; margin-top: 12px; transition: all 0.2s;
}
.article-card .read-more:hover { padding-left: 4px; }

/* === ARTICLE DETAIL PAGE === */
.article-content {
    padding: 40px 0;
}
.article-content .container {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 40px;
    align-items: start;
}
.article-content article {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 40px;
}
.article-content article h1 {
    font-size: clamp(1.6rem, 3vw, 2.2rem);
    font-weight: 800;
    line-height: 1.3;
    margin-bottom: 16px;
}
.article-content article .meta {
    color: var(--text-muted);
    font-size: 0.85rem;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 24px;
}
.article-content article p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: 20px;
}
.article-content article h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin: 32px 0 16px;
    color: var(--text-primary);
    padding-left: 12px;
    border-left: 3px solid var(--accent);
}
.article-content article h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin: 24px 0 12px;
    color: var(--text-primary);
}
.article-content article ul, .article-content article ol {
    margin: 0 0 20px 24px;
    color: var(--text-secondary);
    line-height: 1.8;
}
.article-content article li { margin-bottom: 6px; }
.article-content article blockquote {
    border-left: 4px solid var(--accent);
    padding: 16px 20px;
    margin: 20px 0;
    background: rgba(0,255,136,0.05);
    border-radius: 0 12px 12px 0;
    color: var(--text-secondary);
    font-style: italic;
}
.article-content article a {
    color: var(--accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}
.article-content article a:hover { color: #fff; }

/* Sidebar */
.article-content .sidebar {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 24px;
    position: sticky;
    top: 80px;
}
.article-content .sidebar h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
    color: var(--accent);
}
.article-content .sidebar ul { list-style: none; }
.article-content .sidebar li { margin-bottom: 8px; }
.article-content .sidebar li a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    line-height: 1.4;
    display: block;
    padding: 8px 12px;
    border-radius: 8px;
    transition: all 0.2s;
}
.article-content .sidebar li a:hover {
    background: rgba(0,255,136,0.08);
    color: var(--accent);
    padding-left: 16px;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 40px 20px; text-align: center; color: var(--text-muted); font-size: 0.9rem;
}
.footer a { color: var(--accent); text-decoration: none; }
.footer-links { display: flex; justify-content: center; gap: 20px; margin-bottom: 16px; flex-wrap: wrap; }
.footer-links a { color: var(--text-secondary); font-size: 0.9rem; }
.footer-links a:hover { color: var(--accent); }

/* Responsive */
@media (max-width: 900px) {
    .article-content .container {
        grid-template-columns: 1fr;
    }
    .article-content .sidebar {
        position: static;
    }
    .article-content .sidebar h3 { display: none; }
    .article-content .sidebar ul {
        display: flex;
        flex-wrap: wrap;
        gap: 6px;
    }
    .article-content .sidebar li { margin: 0; }
    .article-content .sidebar li a {
        font-size: 0.8rem;
        padding: 4px 10px;
        border-radius: 20px;
        background: rgba(0,255,136,0.08);
    }
}

@media (max-width: 768px) {
    .mobile-menu-btn { display: block; }
    .nav { display: none; flex-direction: column; position: absolute; top: 100%; left: 0; right: 0; background: var(--bg-secondary); border-bottom: 1px solid var(--border); padding: 10px; }
    .nav.show { display: flex; }
    .hero { padding: 50px 20px; }
    .features-grid, .articles-grid { grid-template-columns: 1fr; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .article-content article { padding: 24px; }
}

@media (max-width: 480px) {
    .stats-grid { grid-template-columns: 1fr; }
    .hero h1 { font-size: 1.6rem; }
    .article-content article { padding: 20px; }
    .article-content article p { font-size: 0.95rem; }
}