.arena-hero {
    padding: 100px 0 60px;
    background: linear-gradient(135deg, rgba(10, 10, 20, 0.95), rgba(20, 10, 30, 0.95));
    position: relative;
    overflow: hidden;
}

.arena-hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        radial-gradient(circle at 20% 50%, rgba(255, 0, 85, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 50%, rgba(0, 255, 255, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.arena-title {
    font-size: 3rem;
    font-weight: 900;
    text-align: center;
    margin-bottom: 8px;
    background: linear-gradient(135deg, #ff0055, #00ffff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-transform: uppercase;
    letter-spacing: 3px;
}

.arena-subtitle {
    font-size: 1.05rem;
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.8;
    margin: 0;
    text-indent: 2em;
}

.highlight-call {
    color: #ff2e4c;
    font-weight: 700;
}

/* ======= Hero 内容左右布局 ======= */
.hero-content-row {
    display: flex;
    gap: 30px;
    align-items: stretch;
}

.hero-text-col {
    flex: 1;
    min-width: 0;
}

.mini-leaderboard {
    background: rgba(20, 20, 35, 0.9);
    border: 1px solid rgba(0, 255, 255, 0.25);
    border-radius: 12px;
    padding: 12px 14px;
    backdrop-filter: blur(10px);
    width: 320px;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
}

.stat-item {
    text-align: center;
    padding: 20px 30px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(0, 255, 255, 0.3);
    border-radius: 10px;
    min-width: 150px;
    backdrop-filter: blur(10px);
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: #00ffff;
    margin-bottom: 5px;
    font-family: 'Orbitron', monospace;
}

.stat-label {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.6);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.challenges-section {
    padding: 60px 0;
    background: linear-gradient(180deg, rgba(10, 10, 20, 0.98), rgba(15, 15, 30, 0.98));
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 20px;
}

.section-title {
    font-size: 2rem;
    color: #fff;
    font-weight: 700;
    margin: 0;
}

.filter-tabs {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(0, 255, 255, 0.3);
    border-radius: 25px;
    color: rgba(255, 255, 255, 0.7);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.filter-btn:hover {
    background: rgba(0, 255, 255, 0.1);
    border-color: #00ffff;
    color: #00ffff;
}

.filter-btn.active {
    background: rgba(0, 255, 255, 0.2);
    border-color: #00ffff;
    color: #00ffff;
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.3);
}

.captcha-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 30px;
}

.captcha-card {
    background: rgba(20, 20, 35, 0.8);
    border: 2px solid rgba(0, 255, 255, 0.2);
    border-radius: 15px;
    padding: 30px;
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
}

.captcha-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(0, 255, 255, 0.1), transparent);
    transition: left 0.5s;
}

.captcha-card:hover::before {
    left: 100%;
}

.captcha-card:hover {
    transform: translateY(-5px);
    border-color: #00ffff;
    box-shadow: 0 10px 30px rgba(0, 255, 255, 0.3);
}

.captcha-header {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
}

.captcha-icon {
    font-size: 3rem;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 10px;
}

.captcha-info h3 {
    font-size: 1.3rem;
    color: #fff;
    margin-bottom: 5px;
    font-weight: 600;
}

.captcha-type {
    font-size: 0.85rem;
    color: rgba(0, 255, 255, 0.8);
    padding: 3px 10px;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 12px;
    display: inline-block;
}

.captcha-description {
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.6;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.captcha-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 15px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.difficulty {
    padding: 5px 12px;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 600;
}

.difficulty-easy {
    background: rgba(0, 255, 136, 0.2);
    color: #00ff88;
    border: 1px solid rgba(0, 255, 136, 0.5);
}

.difficulty-medium {
    background: rgba(255, 170, 0, 0.2);
    color: #ffaa00;
    border: 1px solid rgba(255, 170, 0, 0.5);
}

.difficulty-hard {
    background: rgba(255, 0, 85, 0.2);
    color: #ff0055;
    border: 1px solid rgba(255, 0, 85, 0.5);
}

.difficulty-expert {
    background: rgba(138, 43, 226, 0.2);
    color: #b829ff;
    border: 1px solid rgba(138, 43, 226, 0.5);
}

.completions {
    font-size: 0.85rem;
    padding: 5px 12px;
    border-radius: 15px;
}

.completions.solved {
    background: rgba(0, 255, 136, 0.2);
    color: #00ff88;
}

.completions.unsolved {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.5);
}

@media (max-width: 768px) {
    .arena-title {
        font-size: 2rem;
    }

    .stats-bar {
        gap: 20px;
    }

    .stat-item {
        min-width: 120px;
        padding: 15px 20px;
    }

    .stat-value {
        font-size: 2rem;
    }

    .captcha-grid {
        grid-template-columns: 1fr;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .hero-content-row {
        flex-direction: column;
        align-items: center;
    }

    .hero-text-col {
        text-align: center;
    }

    .mini-leaderboard {
        width: 100%;
        max-width: 400px;
    }

}

/* ======= Hero 居中布局 ======= */
.hero-center {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.hero-badge-img {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    height: 350px;
    object-fit: contain;
    opacity: 1;
    pointer-events: none;
    z-index: 0;
}

@media (max-width: 768px) {
    .hero-badge-img {
        height: 220px;
    }
}

/* ======= Mini Leaderboard Inner Elements ======= */
.mini-lb-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 8px;
}

.mini-lb-title {
    font-size: 0.9rem;
    color: #00ffff;
    letter-spacing: 1px;
    font-weight: 600;
    margin: 0;
}

.mini-leaderboard .refresh-btn {
    padding: 3px 12px;
    font-size: 0.75rem;
    background: rgba(0, 255, 255, 0.08);
    border: 1px solid rgba(0, 255, 255, 0.3);
    border-radius: 14px;
    color: #00ffff;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}
.mini-leaderboard .refresh-btn:hover {
    background: rgba(0, 255, 255, 0.15);
    box-shadow: 0 0 12px rgba(0, 255, 255, 0.2);
}

/* ===== List Style Leaderboard ===== */
.lb-list {
    max-height: 140px;
    overflow-y: auto;
    flex: 1;
}
.lb-list::-webkit-scrollbar { width: 3px; }
.lb-list::-webkit-scrollbar-thumb { background: rgba(0,255,255,0.3); border-radius: 2px; }

.lb-loading {
    text-align: center;
    color: rgba(255,255,255,0.4);
    font-size: 0.8rem;
    padding: 20px 0;
}

.lb-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 5px 8px;
    border-radius: 6px;
    transition: background 0.15s;
}
.lb-item:hover { background: rgba(255,255,255,0.03); }
.lb-item.my-rank { background: rgba(0,255,255,0.08); }

.lb-rank {
    flex-shrink: 0;
    width: 34px;
    height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
}

.lb-rank-num {
    font-size: 0.95rem;
    font-weight: 700;
    color: rgba(255,255,255,0.5);
}

.lb-name {
    flex: 1;
    font-size: 0.98rem;
    color: #fff;
    font-weight: 500;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.lb-score {
    flex-shrink: 0;
    font-size: 0.88rem;
    color: #0f8;
    background: rgba(0,255,136,0.1);
    padding: 3px 10px;
    border-radius: 10px;
    font-weight: 600;
}

.loading-spinner {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(0, 255, 255, 0.3);
    border-top: 2px solid #00ffff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-right: 6px;
    vertical-align: middle;
}

@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }