:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --background: #ffffff;
    --surface: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] {
    --background: #1e293b;
    --surface: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --border: #475569;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    transition: background-color 0.3s, color 0.3s;
}

.app-container {
    min-height: 100vh;
    background-color: var(--background);
}

/* Header */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    background-color: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.menu-btn, .icon-btn {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 0.375rem;
    transition: background-color 0.2s;
}

.menu-btn:hover, .icon-btn:hover {
    background-color: var(--border);
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

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

/* Main Content */
.main-content {
    padding: 1rem;
}

.students-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.student-card {
    display: flex;
    align-items: center;
    padding: 1rem;
    background-color: var(--surface);
    border-radius: 0.75rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}

.progress-circle {
    position: relative;
    width: 60px;
    height: 60px;
    margin-right: 1rem;
}

.circle-bg {
    fill: none;
    stroke: var(--border);
    stroke-width: 3;
}

.circle-progress {
    fill: none;
    stroke: var(--success);
    stroke-width: 3;
    stroke-linecap: round;
    transform: rotate(-90deg);
    transform-origin: 50% 50%;
    transition: stroke-dasharray 0.3s;
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-primary);
}

.student-info {
    flex: 1;
}

.student-name {
    font-weight: 500;
    margin-bottom: 0.25rem;
}

.student-details {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Side Navigation */
.side-nav {
    position: fixed;
    top: 0;
    left: -300px;
    width: 300px;
    height: 100vh;
    background-color: var(--surface);
    border-right: 1px solid var(--border);
    transition: left 0.3s;
    z-index: 1000;
}

.side-nav.active {
    left: 0;
}

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

.nav-content {
    padding: 1rem;
}

.courses-list {
    list-style: none;
    margin-bottom: 1rem;
}

.course-item {
    padding: 0.75rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background-color 0.2s;
    margin-bottom: 0.5rem;
}

.course-item:hover {
    background-color: var(--border);
}

.course-item.active {
    background-color: var(--primary-color);
    color: white;
}

/* Buttons */
.btn-primary {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

.btn-secondary {
    background-color: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border);
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

/* Modals */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 2000;
}

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

.modal-content {
    background-color: var(--surface);
    border-radius: 0.75rem;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
}

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

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    padding: 1.5rem;
    border-top: 1px solid var(--border);
}

/* Form Elements */
.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    background-color: var(--background);
    color: var(--text-primary);
}

.attendance-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
}

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

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

/* Responsive */
@media (max-width: 768px) {
    .header {
        padding: 0.75rem;
    }
    
    .course-title {
        font-size: 1.1rem;
    }
    
    .modal-content {
        width: 95%;
        margin: 1rem;
    }
}

/* Checkbox */
.checkbox-container {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.checkbox-container input[type="checkbox"] {
    width: 1.25rem;
    height: 1.25rem;
}

.remove-student {
    color: var(--error);
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 0.25rem;
}

.remove-student:hover {
    background-color: var(--error);
    color: white;
}

.btn-danger {
    background-color: var(--error);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
    width: 100%;
    margin-top: 0.5rem;
}

.btn-danger:hover {
    background-color: #dc2626;
}

.confirmation-dialog {
    text-align: center;
    padding: 1rem 0;
}

.confirmation-dialog p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

/* Search Styles */
.search-container {
    margin-bottom: 1rem;
}

.search-box {
    position: relative;
    display: flex;
    align-items: center;
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    padding: 0.75rem;
    box-shadow: var(--shadow);
}

.search-box i.fa-search {
    color: var(--text-secondary);
    margin-right: 0.5rem;
}

.search-box input {
    flex: 1;
    border: none;
    background: none;
    color: var(--text-primary);
    font-size: 1rem;
    outline: none;
}

.search-box input::placeholder {
    color: var(--text-secondary);
}

.clear-search {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 0.25rem;
    transition: background-color 0.2s;
}

.clear-search:hover {
    background-color: var(--border);
    color: var(--text-primary);
}

/* Search Results Highlight */
.student-card.highlight {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.1);
}

.attendance-item.highlight {
    background-color: rgba(79, 70, 229, 0.05);
    border-left: 3px solid var(--primary-color);
}

/* No Results Message */
.no-results {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
}

.no-results i {
    font-size: 2rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.suggestion {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
    opacity: 0.7;
}

/* Search focus states */
.search-box:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.1);
}