/* CSS Variables for Color Palette */
:root {
    --primary-color: #05386B;
    --secondary-color: #379683;
    --accent-color: #5CDB95;
    --light-accent: #8EE4AF;
    --background-color: #EDF5E1;
    --white: #ffffff;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
    --border-color: #e1e8ed;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --gradient-primary: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    --gradient-accent: linear-gradient(135deg, var(--accent-color), var(--light-accent));
    --gradient-bg: linear-gradient(135deg, var(--background-color), var(--white));
}

/* Dark Theme Variables */
[data-theme="dark"] {
    --background-color: #1a1a1a;
    --white: #2d2d2d;
    --text-dark: #ffffff;
    --text-light: #b0b0b0;
    --border-color: #404040;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    --gradient-bg: linear-gradient(135deg, #1a1a1a, #2d2d2d);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--gradient-bg);
    color: var(--text-dark);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.app-container {
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
.header {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 1rem 0;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: bold;
}

.logo i {
    font-size: 2rem;
}

.main-nav {
    display: flex;
    gap: 1rem;
}

.nav-btn {
    background: transparent;
    border: none;
    color: var(--white);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.9rem;
}

.nav-btn:hover,
.nav-btn.active {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.nav-btn i {
    font-size: 1.2rem;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    background: transparent;
    border: none;
    color: var(--white);
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.2);
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1rem;
}

/* Main Content */
.main-content {
    flex: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    width: 100%;
}

.content-section {
    display: none;
}

.content-section.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.section-header h1 {
    color: var(--primary-color);
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-light);
    font-size: 1.1rem;
}

/* Dashboard Styles */
.dashboard-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: transform 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-icon {
    background: var(--gradient-accent);
    color: var(--white);
    width: 60px;
    height: 60px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.stat-content h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.stat-content p {
    color: var(--text-light);
    font-size: 0.9rem;
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.dashboard-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.dashboard-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.quick-actions {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.quick-btn {
    background: var(--gradient-accent);
    color: var(--white);
    border: none;
    padding: 0.75rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.quick-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* Button Styles */
.btn-primary,
.btn-secondary {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
}

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

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

.btn-primary:hover,
.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* Filters Bar */
.filters-bar {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.filters-bar input,
.filters-bar select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--white);
    color: var(--text-dark);
    font-size: 1rem;
    min-width: 200px;
}

.filters-bar input:focus,
.filters-bar select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(92, 219, 149, 0.1);
}

/* Table Styles */
.table-container {
    background: var(--white);
    border-radius: 12px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

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

.data-table th {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 1rem;
    text-align: left;
    font-weight: 600;
}

.data-table td {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.data-table tbody tr:hover {
    background: rgba(92, 219, 149, 0.1);
}

.status-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
}

.status-active {
    background: #d4edda;
    color: #155724;
}

.status-inactive {
    background: #f8d7da;
    color: #721c24;
}

.status-paid {
    background: #d1ecf1;
    color: #0c5460;
}

.status-pending {
    background: #fff3cd;
    color: #856404;
}

.status-overdue {
    background: #f8d7da;
    color: #721c24;
}

.action-btn {
    background: transparent;
    border: none;
    color: var(--primary-color);
    cursor: pointer;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    transition: all 0.3s ease;
    margin: 0 0.25rem;
}

.action-btn:hover {
    background: rgba(5, 56, 107, 0.1);
}

.action-btn.delete {
    color: #dc3545;
}

.action-btn.delete:hover {
    background: rgba(220, 53, 69, 0.1);
}

/* Classes Grid */
.classes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.class-card {
    background: var(--white);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    transition: transform 0.3s ease;
}

.class-card:hover {
    transform: translateY(-5px);
}

.class-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.class-title {
    color: var(--primary-color);
    font-size: 1.3rem;
    margin-bottom: 0.25rem;
}

.class-subject {
    color: var(--text-light);
    font-size: 0.9rem;
}

.class-info {
    margin-bottom: 1rem;
}

.class-info p {
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.class-info i {
    color: var(--accent-color);
    width: 16px;
}

.class-actions {
    display: flex;
    gap: 0.5rem;
}

/* Calendar Styles */
.calendar-container {
    background: var(--white);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
}

.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.calendar-header button {
    background: var(--gradient-primary);
    color: var(--white);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.calendar-header button:hover {
    transform: translateY(-2px);
}

.calendar-header h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 1px;
    background: var(--border-color);
    border-radius: 8px;
    overflow: hidden;
}

.calendar-day {
    background: var(--white);
    padding: 1rem;
    min-height: 100px;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.calendar-day.other-month {
    background: #f8f9fa;
    color: var(--text-light);
}

.calendar-day.today {
    background: rgba(92, 219, 149, 0.1);
    border: 2px solid var(--accent-color);
}

.day-number {
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.calendar-event {
    background: var(--gradient-accent);
    color: var(--white);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
    cursor: pointer;
}

/* Reports Grid */
.reports-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 1.5rem;
}

.report-card {
    background: var(--white);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
}

.report-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.report-actions {
    display: flex;
    gap: 1rem;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal-content {
    background: var(--white);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    max-width: 600px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
}

.modal-header h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
    padding: 0.25rem;
}

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

.modal-form {
    padding: 0 1.5rem 1.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
    font-weight: 600;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--white);
    color: var(--text-dark);
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(92, 219, 149, 0.1);
}

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

.modal-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

/* Footer */
.footer {
    background: var(--gradient-primary);
    color: var(--white);
    text-align: center;
    padding: 1rem;
    margin-top: auto;
}

.footer p {
    margin: 0;
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
        padding: 0 1rem;
    }

    .main-nav {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav-btn {
        font-size: 0.8rem;
        padding: 0.5rem 0.75rem;
    }

    .nav-btn span {
        display: none;
    }

    .main-content {
        padding: 1rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

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

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

    .filters-bar {
        flex-direction: column;
    }

    .filters-bar input,
    .filters-bar select {
        min-width: 100%;
    }

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

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

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

    .calendar-day {
        padding: 0.5rem;
        min-height: 80px;
    }

    .modal-content {
        margin: 1rem;
        max-height: calc(100vh - 2rem);
    }

    .report-actions {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .nav-btn i {
        font-size: 1rem;
    }

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

    .calendar-grid {
        font-size: 0.8rem;
    }

    .calendar-day {
        padding: 0.25rem;
        min-height: 60px;
    }

    .modal-actions {
        flex-direction: column;
    }
}

/* Loading and Animation States */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

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

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

/* Utility Classes */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.hidden { display: none; }
.visible { display: block; }

/* Accessibility */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles for better accessibility */
button:focus,
input:focus,
select:focus,
textarea:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
        --border-color: #000000;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}