:root {
    --gradient-start: #667eea;
    --gradient-end: #764ba2;
    --text-primary: #333;
    --text-secondary: #495057;
    --text-light: #6c757d;
    --card-bg: #ffffff;
    --table-header-bg: #f8f9fa;
    --table-border: #dee2e6;
    --table-row-border: #e9ecef;
    --table-hover-bg: #f8f9fa;
    --rank-gold: #FFD700;
    --rank-silver: #C0C0C0;
    --rank-bronze: #CD7F32;
    --score-color: #667eea;
    --error-color: #dc3545;
    --heading-color: #ffffff;
    --tab-bg: rgba(255, 255, 255, 0.2);
    --tab-border: rgba(255, 255, 255, 0.3);
    --tab-text: #ffffff;
    --tab-hover-bg: rgba(255, 255, 255, 0.3);
    --tab-active-bg: #ffffff;
    --tab-active-text: #667eea;
    --tab-active-border: #ffffff;
}

@media (prefers-color-scheme: dark) {
    :root {
        --gradient-start: #4a5fd6;
        --gradient-end: #5e3a7a;
        --text-primary: #e4e4e7;
        --text-secondary: #a1a1aa;
        --text-light: #71717a;
        --card-bg: #1f2937;
        --table-header-bg: #111827;
        --table-border: #374151;
        --table-row-border: #374151;
        --table-hover-bg: #374151;
        --rank-gold: #fbbf24;
        --rank-silver: #d1d5db;
        --rank-bronze: #fb923c;
        --score-color: #818cf8;
        --error-color: #f87171;
        --heading-color: #f3f4f6;
        --tab-bg: rgba(31, 41, 55, 0.6);
        --tab-border: rgba(75, 85, 99, 0.5);
        --tab-text: #e5e7eb;
        --tab-hover-bg: rgba(55, 65, 81, 0.8);
        --tab-active-bg: #374151;
        --tab-active-text: #818cf8;
        --tab-active-border: #6366f1;
    }
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--gradient-start) 0%, var(--gradient-end) 100%);
    min-height: 100vh;
    padding: 20px;
    color: var(--text-primary);
}

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

h1 {
    text-align: center;
    color: var(--heading-color);
    margin-bottom: 30px;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.tabs {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.tab {
    background: var(--tab-bg);
    border: 2px solid var(--tab-border);
    color: var(--tab-text);
    padding: 12px 30px;
    cursor: pointer;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: bold;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.tab:hover {
    background: var(--tab-hover-bg);
    transform: translateY(-2px);
}

.tab.active {
    background: var(--tab-active-bg);
    color: var(--tab-active-text);
    border-color: var(--tab-active-border);
}

.leaderboard-card {
    background: var(--card-bg);
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    overflow: hidden;
}

.leaderboard-header {
    background: linear-gradient(135deg, var(--gradient-start) 0%, var(--gradient-end) 100%);
    color: white;
    padding: 20px;
    text-align: center;
}

.leaderboard-header h2 {
    font-size: 1.8em;
    margin-bottom: 5px;
}

.leaderboard-header p {
    opacity: 0.9;
    font-size: 0.95em;
}

.leaderboard-table {
    width: 100%;
    border-collapse: collapse;
}

.leaderboard-table thead {
    background: var(--table-header-bg);
    border-bottom: 2px solid var(--table-border);
}

.leaderboard-table th {
    padding: 15px;
    text-align: left;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    font-size: 0.85em;
    letter-spacing: 0.5px;
}

.leaderboard-table th:first-child {
    width: 80px;
    text-align: center;
}

.leaderboard-table th:nth-child(4) {
    text-align: right;
}

.stat {
    color: var(--text-secondary);
}

.leaderboard-table tbody tr {
    border-bottom: 1px solid var(--table-row-border);
    transition: background-color 0.2s ease;
}

.leaderboard-table tbody tr:hover {
    background-color: var(--table-hover-bg);
}

.leaderboard-table td {
    padding: 15px;
}

.rank {
    text-align: center;
    font-weight: bold;
    font-size: 1.2em;
}

.rank-1 { color: var(--rank-gold); }
.rank-2 { color: var(--rank-silver); }
.rank-3 { color: var(--rank-bronze); }

.username {
    font-weight: 500;
    color: var(--text-primary);
}

.score {
    text-align: right;
    font-weight: bold;
    color: var(--score-color);
    font-size: 1.1em;
}

.loading {
    text-align: center;
    padding: 40px;
    color: var(--text-light);
    font-size: 1.1em;
}

.error {
    text-align: center;
    padding: 40px;
    color: var(--error-color);
    font-size: 1.1em;
}

.empty {
    text-align: center;
    padding: 40px;
    color: var(--text-light);
    font-size: 1.1em;
}

.medal {
    display: inline-block;
    margin-right: 5px;
    font-size: 1.3em;
}

@media (max-width: 768px) {
    h1 {
        font-size: 1.8em;
    }

    .tabs {
        gap: 5px;
    }

    .tab {
        padding: 10px 20px;
        font-size: 1em;
    }

    .leaderboard-table th,
    .leaderboard-table td {
        padding: 10px 8px;
        font-size: 0.9em;
    }

    .leaderboard-header h2 {
        font-size: 1.4em;
    }
}