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

body {
    font-family: 'Cal Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #000000;
    color: #ffffff;
    overflow-x: hidden;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #333333;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 100;
    height: 80px;
}

h1 {
    font-size: 24px;
    font-weight: 600;
    color: #ffff00;
}

.stats {
    display: flex;
    gap: 30px;
}

.stat {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 20px;
    font-weight: 600;
    color: #ffff00;
}

.stat-label {
    font-size: 12px;
    color: #cccccc;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.search-container {
    position: fixed;
    top: 90px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 10px;
    z-index: 99;
    background: rgba(0, 0, 0, 0.95);
    backdrop-filter: blur(10px);
    padding: 15px;
    border-radius: 8px;
    border: 1px solid #333333;
}

#search-input {
    padding: 10px 15px;
    border: 1px solid #666666;
    border-radius: 6px;
    font-size: 14px;
    width: 200px;
    font-family: inherit;
    background: #111111;
    color: #ffffff;
}

#search-input::placeholder {
    color: #888888;
}

#go-button {
    padding: 10px 20px;
    background: #ffff00;
    color: #000000;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-family: inherit;
    transition: background 0.2s ease;
}

#go-button:hover {
    background: #e6e600;
}

.viewport {
    margin-top: 160px;
    padding: 20px;
    min-height: calc(100vh - 160px);
}

.checkbox-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(40px, 1fr));
    gap: 8px;
    max-width: 1200px;
    margin: 0 auto;
}

.checkbox-item {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 6px;
    border: 1px solid #666666;
    background: #111111;
    cursor: pointer;
    transition: all 0.15s ease;
    user-select: none;
}

.checkbox-item:hover {
    border-color: #ffff00;
    transform: scale(1.05);
}

.checkbox-item.checked {
    background: #ffff00;
    border-color: #ffff00;
}

.checkbox-item.checked::after {
    content: '✓';
    color: #000000;
    font-size: 16px;
    font-weight: bold;
}

.checkbox-item .number {
    display: none;
}

.loading {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 18px;
    color: #cccccc;
    z-index: 1000;
}

.hidden {
    display: none;
}

/* Animation for newly checked boxes */
@keyframes checkAnimation {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.checkbox-item.animate-check {
    animation: checkAnimation 0.3s ease;
}

.checkbox-item.highlighted {
    background: #ffff00;
    border-color: #ffff00;
    animation: highlightPulse 2s ease;
}

@keyframes highlightPulse {
    0% { background: #ffff00; }
    50% { background: #e6e600; }
    100% { background: #ffff00; }
}

/* Responsive design */
@media (max-width: 768px) {
    .header {
        padding: 15px;
        height: 70px;
    }
    
    h1 {
        font-size: 20px;
    }
    
    .stats {
        gap: 20px;
    }
    
    .stat-number {
        font-size: 18px;
    }
    
    .search-container {
        top: 80px;
        padding: 10px;
    }
    
    #search-input {
        width: 150px;
        padding: 8px 12px;
    }
    
    #go-button {
        padding: 8px 16px;
    }
    
    .viewport {
        margin-top: 140px;
        padding: 15px;
    }
    
    .checkbox-grid {
        grid-template-columns: repeat(auto-fill, minmax(35px, 1fr));
        gap: 6px;
    }
    
    .checkbox-item {
        width: 35px;
        height: 35px;
    }
}