body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    margin: 0;
    padding: 0;
    color: #000000;
}

.dashboard-container {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 250px;
    background: linear-gradient(180deg, #000000 0%, #1a1a1a 100%);
    color: white;
    padding: 20px 0;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    border-right: 3px solid #dc3545;
    box-shadow: 2px 0 10px rgba(0,0,0,0.1);
}

.sidebar-header {
    text-align: center;
    margin-bottom: 30px;
    padding: 0 20px;
}

.sidebar-header h2 {
    margin: 0;
    color: #007bff;
    font-size: 24px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.sidebar nav ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
}

.sidebar nav li {
    margin: 0;
}

.sidebar nav a {
    display: block;
    padding: 15px 20px;
    text-decoration: none;
    color: #adb5bd;
    transition: all 0.3s ease;
    border-left: 4px solid transparent;
}

.sidebar nav a:hover {
    background: linear-gradient(90deg, #dc3545 0%, #c82333 100%);
    color: white;
    border-left: 4px solid #007bff;
    transform: translateX(5px);
}

.sidebar nav a.active {
    background: linear-gradient(90deg, #007bff 0%, #0056b3 100%);
    color: white;
    border-left: 4px solid #dc3545;
    box-shadow: 0 2px 8px rgba(0,123,255,0.3);
}

.main-content {
    flex: 1;
    margin-left: 250px;
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
}

header {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    padding: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    border-bottom: 3px solid #007bff;
}

header h1 {
    margin: 0;
    color: #000000;
    font-weight: 700;
    text-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.user-info {
    font-weight: 500;
    color: #000000;
}

.user-info a {
    color: #dc3545;
    text-decoration: none;
    margin-left: 15px;
    font-weight: 600;
    transition: all 0.3s ease;
}

.user-info a:hover {
    color: #007bff;
    text-decoration: underline;
}

main {
    padding: 20px;
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    margin: 0 20px 20px;
    border-radius: 12px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    border: 1px solid #e9ecef;
}

h2 {
    color: #000000;
    margin-bottom: 20px;
    font-size: 28px;
    font-weight: 700;
    text-shadow: 0 1px 2px rgba(0,0,0,0.1);
    border-bottom: 2px solid #007bff;
    padding-bottom: 10px;
}

/* Cards */
.stats-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.card {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 2px solid #007bff;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #dc3545 0%, #007bff 100%);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.2);
    border-color: #dc3545;
}

.card h3 {
    margin: 0 0 15px 0;
    color: #000000;
    font-size: 18px;
    font-weight: 600;
}

.card p {
    font-size: 32px;
    font-weight: bold;
    color: #dc3545;
    margin: 0;
    text-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

/* Charts */
.charts {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 20px;
}

.chart-container {
    background-color: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    border: 1px solid #e9ecef;
}

.chart-container h3 {
    margin-top: 0;
    color: #495057;
    margin-bottom: 20px;
}

.chart-container canvas {
    max-width: 100%;
    height: auto;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .stats-cards {
        grid-template-columns: 1fr;
    }
    
    .charts {
        grid-template-columns: 1fr;
    }
}

/* Login page */
.login-container {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.2);
    width: 100%;
    max-width: 400px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    border: 2px solid #007bff;
}

.login-container h1 {
    color: #000000;
    margin-bottom: 30px;
    font-weight: 700;
    text-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

/* Form elements */
.form-group {
    margin-bottom: 20px;
    text-align: left;
}

label {
    display: block;
    margin-bottom: 8px;
    color: #495057;
    font-weight: 500;
}

input, select, textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    font-size: 16px;
    transition: all 0.3s ease;
    background-color: #ffffff;
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: #007bff;
    box-shadow: 0 0 0 3px rgba(0,123,255,0.1);
    background-color: #f8f9fa;
}

button {
    padding: 12px 24px;
    background: linear-gradient(135deg, #dc3545 0%, #c82333 100%);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s ease;
    width: 100%;
    box-shadow: 0 2px 4px rgba(220,53,69,0.3);
}

button:hover {
    background: linear-gradient(135deg, #c82333 0%, #a02622 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(220,53,69,0.4);
}

.error {
    background: linear-gradient(135deg, #f8d7da 0%, #f5c6cb 100%);
    color: #721c24;
    text-align: center;
    margin-top: 15px;
    font-weight: 500;
    padding: 10px;
    border-radius: 8px;
    border: 1px solid #dc3545;
}

.message {
    background: linear-gradient(135deg, #d4edda 0%, #c3e6cb 100%);
    color: #155724;
    text-align: center;
    margin-top: 15px;
    font-weight: 500;
    padding: 10px;
    border-radius: 8px;
    border: 1px solid #28a745;
}

.button {
    padding: 12px 24px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.button:hover {
    background-color: #0056b3;
    text-decoration: none;
    color: white;
}

.report-filters {
    margin-bottom: 20px;
}

.report-filters a {
    margin-right: 20px;
    color: #007bff;
    text-decoration: none;
}

.report-filters a:hover {
    text-decoration: underline;
}

.student-summary {
    background-color: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.student-summary p {
    margin: 10px 0;
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    border: 1px solid #e9ecef;
}

th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #e9ecef;
}

th {
    background: linear-gradient(135deg, #007bff 0%, #0056b3 100%);
    color: white;
    font-weight: 600;
    text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

tr:hover {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    transform: scale(1.01);
    transition: all 0.2s ease;
}

/* Student Selection Styles */
.student-selection {
    background-color: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    margin: 20px 0;
    border: 1px solid #e9ecef;
}

.select-all {
    background-color: #007bff;
    color: white;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 15px;
    font-weight: 500;
}

.select-all label {
    cursor: pointer;
    margin: 0;
}

.select-all input[type="checkbox"] {
    margin-right: 10px;
    transform: scale(1.2);
}

.student-checkbox {
    background-color: white;
    padding: 12px 15px;
    margin-bottom: 8px;
    border-radius: 6px;
    border: 1px solid #e9ecef;
    transition: all 0.3s ease;
}

.student-checkbox:hover {
    background-color: #f1f3f4;
    border-color: #007bff;
}

.student-checkbox label {
    cursor: pointer;
    margin: 0;
    display: flex;
    align-items: center;
}

.student-checkbox input[type="checkbox"] {
    margin-right: 12px;
    transform: scale(1.1);
}

.form-actions {
    margin-top: 20px;
    display: flex;
    gap: 15px;
    align-items: center;
}

.button-secondary {
    padding: 12px 24px;
    background: linear-gradient(135deg, #6c757d 0%, #5a6268 100%);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    box-shadow: 0 2px 4px rgba(108,117,125,0.3);
}

.button-secondary:hover {
    background: linear-gradient(135deg, #5a6268 0%, #495057 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(108,117,125,0.4);
    text-decoration: none;
    color: white;
}

/* Search and Filter Styles */
.search-filter {
    margin-bottom: 15px;
}

.search-input {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: #007bff;
}

.student-count {
    margin-left: 10px;
    color: #6c757d;
    font-size: 14px;
}

.student-info {
    flex: 1;
}

.student-info strong {
    color: #007bff;
}

/* Payment Summary Styles */
.payment-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin: 20px 0;
}

.summary-card {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    text-align: center;
    border: 2px solid #007bff;
    position: relative;
    overflow: hidden;
}

.summary-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #dc3545 0%, #007bff 100%);
}

.summary-card h4 {
    margin: 0 0 10px 0;
    color: #000000;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-weight: 600;
}

.summary-card .amount {
    font-size: 24px;
    font-weight: bold;
    color: #dc3545;
    margin: 0;
    text-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.summary-card .count {
    font-size: 18px;
    font-weight: 500;
    color: #007bff;
    margin: 0;
}

/* Status Styles */
.status-completed {
    background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
    color: white;
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 500;
    text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

.no-data {
    text-align: center;
    color: #6c757d;
    font-style: italic;
    padding: 20px;
}

/* Form Help Text */
.form-help {
    display: block;
    margin-top: 5px;
    color: #6c757d;
    font-size: 12px;
    font-style: italic;
}

/* Sorting indicators */
.sortable {
    cursor: pointer;
    position: relative;
}

.sort-asc::after {
    content: ' ↑';
    color: #dc3545;
    font-weight: bold;
}

.sort-desc::after {
    content: ' ↓';
    color: #dc3545;
    font-weight: bold;
}