/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #059669;
    --danger-color: #dc2626;
    --warning-color: #d97706;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    --radius: 8px;
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 14px;
}

/* Container */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
}

/* Header */
.header {
    background: var(--card-bg);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
}

.header h1 {
    color: var(--primary-color);
    font-size: 24px;
    font-weight: 700;
}

.stats {
    display: flex;
    gap: 20px;
    font-size: 14px;
    color: var(--text-secondary);
}

.stats span {
    background: var(--bg-color);
    padding: 5px 10px;
    border-radius: 20px;
    font-weight: 500;
}

/* Controls */
.controls {
    background: var(--card-bg);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.search-container {
    position: relative;
    margin-bottom: 20px;
}

.search-input {
    width: 100%;
    padding: 12px 40px 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 14px;
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.clear-btn {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 5px;
    border-radius: 50%;
    transition: var(--transition);
}

.clear-btn:hover {
    background: var(--bg-color);
    color: var(--danger-color);
}

.filter-controls {
    display: grid;
    gap: 20px;
    margin-bottom: 20px;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.filter-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
}

.alphabet-filter, .number-filter {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
}

.filter-btn {
    padding: 6px 12px;
    border: 1px solid var(--border-color);
    background: var(--card-bg);
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: var(--transition);
    min-width: 30px;
    text-align: center;
}

.filter-btn:hover {
    background: var(--bg-color);
    border-color: var(--primary-color);
}

.filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.action-buttons {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: #1d4ed8;
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--secondary-color);
    color: white;
}

.btn-secondary:hover {
    background: #475569;
    transform: translateY(-1px);
}

/* Table Container */
.table-container {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    margin-bottom: 20px;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
}

.data-table th {
    background: var(--bg-color);
    padding: 15px 12px;
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 10;
}

.data-table th.sortable {
    cursor: pointer;
    user-select: none;
    transition: var(--transition);
}

.data-table th.sortable:hover {
    background: #f1f5f9;
}

.data-table th i {
    margin-left: 5px;
    font-size: 10px;
    color: var(--text-secondary);
}

.data-table td {
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
    vertical-align: top;
}

.data-table tbody tr {
    transition: var(--transition);
}

.data-table tbody tr:hover {
    background: #f8fafc;
}

.data-table tbody tr:nth-child(even) {
    background: #fafbfc;
}

.data-table tbody tr:nth-child(even):hover {
    background: #f1f5f9;
}

/* Responsive Table */
@media screen and (max-width: 768px) {
    .table-container {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    .data-table {
        min-width: 600px;
    }
    
    .data-table th,
    .data-table td {
        padding: 10px 8px;
        font-size: 12px;
    }
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 5px;
    flex-wrap: wrap;
}

.pagination button {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    background: var(--card-bg);
    border-radius: 4px;
    cursor: pointer;
    font-size: 13px;
    transition: var(--transition);
    min-width: 35px;
}

.pagination button:hover {
    background: var(--bg-color);
    border-color: var(--primary-color);
}

.pagination button.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.pagination button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.pagination-info {
    color: var(--text-secondary);
    font-size: 14px;
    margin: 0 10px;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.9);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    transition: var(--transition);
}

.loading-overlay.hidden {
    opacity: 0;
    visibility: hidden;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 15px;
}

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

.loading-overlay p {
    color: var(--text-secondary);
    font-size: 14px;
}

/* Mobile Optimizations */
@media screen and (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .header {
        padding: 15px;
        flex-direction: column;
        text-align: center;
    }
    
    .header h1 {
        font-size: 20px;
    }
    
    .controls {
        padding: 15px;
    }
    
    .filter-controls {
        gap: 15px;
    }
    
    .alphabet-filter, .number-filter {
        gap: 3px;
    }
    
    .filter-btn {
        padding: 5px 8px;
        font-size: 11px;
        min-width: 25px;
    }
    
    .action-buttons {
        justify-content: center;
    }
    
    .btn {
        padding: 8px 16px;
        font-size: 13px;
    }
    
    .stats {
        flex-direction: column;
        gap: 5px;
        width: 100%;
    }
}

@media screen and (max-width: 480px) {
    .header h1 {
        font-size: 18px;
    }
    
    .alphabet-filter, .number-filter {
        gap: 2px;
    }
    
    .filter-btn {
        padding: 4px 6px;
        font-size: 10px;
        min-width: 22px;
    }
    
    .pagination button {
        padding: 6px 8px;
        font-size: 12px;
        min-width: 30px;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #0f172a;
        --card-bg: #1e293b;
        --text-primary: #f1f5f9;
        --text-secondary: #94a3b8;
        --border-color: #334155;
    }
    
    .data-table tbody tr:nth-child(even) {
        background: #1e293b;
    }
    
    .data-table tbody tr:nth-child(even):hover {
        background: #334155;
    }
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Focus styles for accessibility */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Custom scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-color);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}