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

:root {
    --primary-color: #4a90d9;
    --success-color: #52c41a;
    --danger-color: #ff4d4f;
    --warning-color: #faad14;
    --info-color: #1890ff;
    --text-color: #333;
    --text-secondary: #666;
    --border-color: #e8e8e8;
    --bg-color: #f5f5f5;
    --card-bg: #fff;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

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

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

.header {
    background: linear-gradient(135deg, var(--primary-color), #6eb6ff);
    color: white;
    padding: 25px 30px;
    border-radius: 12px;
    margin-bottom: 25px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
}

.header h1 {
    font-size: 28px;
    font-weight: 600;
}

.teacher-info {
    font-size: 16px;
}

.teacher-info strong {
    font-weight: 600;
}

.nav-tabs {
    display: flex;
    gap: 8px;
    background: var(--card-bg);
    padding: 8px;
    border-radius: 10px;
    margin-bottom: 25px;
    box-shadow: var(--shadow);
    overflow-x: auto;
    flex-wrap: wrap;
}

.nav-tab {
    padding: 12px 20px;
    border: none;
    background: transparent;
    cursor: pointer;
    border-radius: 8px;
    font-size: 14px;
    color: var(--text-secondary);
    transition: all 0.3s;
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav-tab:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}

.nav-tab.active {
    background: var(--primary-color);
    color: white;
}

.tab-icon {
    font-size: 16px;
}

.main-content {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
    min-height: 500px;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
}

.section-header h2 {
    font-size: 22px;
    color: var(--text-color);
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

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

.btn-primary:hover {
    background: #3a7fc9;
}

.btn-secondary {
    background: #e8e8e8;
    color: var(--text-color);
}

.btn-secondary:hover {
    background: #d8d8d8;
}

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

.btn-success:hover {
    background: #47a011;
}

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

.btn-danger:hover {
    background: #e43d3f;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 25px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: var(--shadow);
}

.stat-card:nth-child(2) {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.stat-card:nth-child(3) {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.stat-card:nth-child(4) {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

.stat-icon {
    font-size: 42px;
}

.stat-value {
    font-size: 32px;
    font-weight: 700;
}

.stat-label {
    font-size: 14px;
    opacity: 0.9;
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 25px;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
}

.card h3 {
    font-size: 18px;
    margin-bottom: 15px;
    color: var(--text-color);
}

.rankings-list, .recent-records {
    max-height: 350px;
    overflow-y: auto;
}

.ranking-item {
    display: flex;
    align-items: center;
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s;
}

.ranking-item:last-child {
    border-bottom: none;
}

.ranking-item:hover {
    background: var(--bg-color);
}

.ranking-position {
    width: 30px;
    height: 30px;
    border-radius: 50%;
    background: var(--primary-color);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    margin-right: 15px;
    font-size: 14px;
}

.ranking-position.gold {
    background: linear-gradient(135deg, #f5af19, #f12711);
}

.ranking-position.silver {
    background: linear-gradient(135deg, #c0c0c0, #a0a0a0);
}

.ranking-position.bronze {
    background: linear-gradient(135deg, #cd7f32, #b8860b);
}

.ranking-info {
    flex: 1;
}

.ranking-name {
    font-weight: 600;
    color: var(--text-color);
}

.ranking-class {
    font-size: 12px;
    color: var(--text-secondary);
}

.ranking-points {
    font-weight: 700;
    color: var(--primary-color);
    font-size: 16px;
}

.record-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
}

.record-item:last-child {
    border-bottom: none;
}

.record-info {
    flex: 1;
}

.record-student {
    font-weight: 600;
}

.record-reason {
    font-size: 13px;
    color: var(--text-secondary);
}

.record-time {
    font-size: 12px;
    color: #999;
}

.record-points {
    font-weight: 700;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 14px;
}

.record-points.positive {
    background: #e6f7ff;
    color: var(--success-color);
}

.record-points.negative {
    background: #fff1f0;
    color: var(--danger-color);
}

.search-box {
    margin-bottom: 20px;
}

.search-box input {
    width: 100%;
    max-width: 400px;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.3s;
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.table-container {
    overflow-x: auto;
}

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

.data-table th, .data-table td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.data-table th {
    background: var(--bg-color);
    font-weight: 600;
    color: var(--text-color);
    font-size: 14px;
}

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

.data-table .loading {
    text-align: center;
    color: var(--text-secondary);
    padding: 40px;
}

.status-badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.status-badge.active {
    background: #e6f7ff;
    color: var(--success-color);
}

.status-badge.inactive {
    background: #f5f5f5;
    color: #999;
}

.action-btns {
    display: flex;
    gap: 8px;
}

.action-btn {
    padding: 6px 12px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    transition: all 0.2s;
}

.action-btn.edit {
    background: #e6f7ff;
    color: var(--primary-color);
}

.action-btn.edit:hover {
    background: #bae0ff;
}

.action-btn.delete {
    background: #fff1f0;
    color: var(--danger-color);
}

.action-btn.delete:hover {
    background: #ffccc7;
}

.action-btn.view {
    background: #f9f0ff;
    color: #722ed1;
}

.action-btn.view:hover {
    background: #d3adf7;
}

.groups-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 20px;
}

.group-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    transition: all 0.3s;
}

.group-card:hover {
    box-shadow: var(--shadow);
    transform: translateY(-2px);
}

.group-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
}

.group-name {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
}

.group-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 15px;
}

.group-stats {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 15px;
}

.group-actions {
    display: flex;
    gap: 8px;
}

.prizes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.prize-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    transition: all 0.3s;
}

.prize-card:hover {
    box-shadow: var(--shadow);
    transform: translateY(-3px);
}

.prize-card.out-of-stock {
    opacity: 0.6;
}

.prize-icon {
    font-size: 48px;
    margin-bottom: 15px;
}

.prize-name {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
}

.prize-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.prize-points {
    font-size: 20px;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.prize-stock {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 15px;
}

.prize-stock span {
    color: var(--success-color);
    font-weight: 600;
}

.quick-add {
    margin-bottom: 25px;
}

.quick-add h3 {
    color: var(--success-color);
}

.form-row {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
    align-items: flex-end;
}

.form-group {
    flex: 1;
    min-width: 150px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    color: var(--text-color);
    font-weight: 500;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 14px;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group textarea {
    min-height: 80px;
    resize: vertical;
}

.required {
    color: var(--danger-color);
}

.filter-row {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
    align-items: flex-end;
    margin-bottom: 20px;
}

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

.exchange-info {
    background: var(--bg-color);
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
}

.info-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}

.info-item:last-child {
    margin-bottom: 0;
}

.info-item strong {
    color: var(--primary-color);
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--card-bg);
    border-radius: 12px;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow: hidden;
    animation: modalSlide 0.3s ease;
}

.modal-content.modal-large {
    max-width: 700px;
}

.modal-content.modal-small {
    max-width: 400px;
}

@keyframes modalSlide {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    padding: 20px 25px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    font-size: 18px;
    color: var(--text-color);
}

.modal-close {
    width: 32px;
    height: 32px;
    border: none;
    background: transparent;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-secondary);
    border-radius: 4px;
    transition: all 0.2s;
}

.modal-close:hover {
    background: var(--bg-color);
    color: var(--text-color);
}

.modal-body {
    padding: 25px;
    max-height: calc(90vh - 140px);
    overflow-y: auto;
}

.modal-footer {
    padding: 15px 25px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.search-select {
    position: relative;
}

.search-results {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    max-height: 200px;
    overflow-y: auto;
    display: none;
    z-index: 10;
    box-shadow: var(--shadow);
}

.search-results.active {
    display: block;
}

.search-result-item {
    padding: 10px 15px;
    cursor: pointer;
    transition: background 0.2s;
}

.search-result-item:hover {
    background: var(--bg-color);
}

.group-students-list {
    margin-top: 20px;
}

.group-student-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 8px;
}

.group-student-item:hover {
    background: var(--bg-color);
}

.group-student-info {
    flex: 1;
}

.group-student-name {
    font-weight: 600;
}

.group-student-no {
    font-size: 12px;
    color: var(--text-secondary);
}

.group-student-remove {
    color: var(--danger-color);
    cursor: pointer;
    padding: 5px;
}

.group-student-remove:hover {
    opacity: 0.7;
}

.toast {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 25px;
    border-radius: 8px;
    color: white;
    font-size: 14px;
    z-index: 2000;
    animation: toastSlide 0.3s ease;
    display: none;
}

.toast.success {
    background: var(--success-color);
}

.toast.error {
    background: var(--danger-color);
}

.toast.info {
    background: var(--info-color);
}

@keyframes toastSlide {
    from {
        opacity: 0;
        transform: translateX(100px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.loading {
    text-align: center;
    color: var(--text-secondary);
    padding: 40px;
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }

    .header {
        flex-direction: column;
        text-align: center;
        gap: 15px;
        padding: 20px;
    }

    .header h1 {
        font-size: 22px;
    }

    .nav-tabs {
        gap: 4px;
        padding: 6px;
    }

    .nav-tab {
        padding: 10px 14px;
        font-size: 13px;
    }

    .main-content {
        padding: 15px;
    }

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

    .stat-card {
        padding: 20px;
    }

    .stat-value {
        font-size: 24px;
    }

    .form-row, .filter-row {
        flex-direction: column;
    }

    .form-group {
        min-width: 100%;
    }

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

    .groups-container {
        grid-template-columns: 1fr;
    }

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

    .data-table th, .data-table td {
        padding: 10px 8px;
        font-size: 13px;
    }

    .action-btns {
        flex-direction: column;
        gap: 4px;
    }

    .modal-content {
        width: 95%;
        margin: 10px;
    }
}