:root {
    --primary: #4361ee;
    --primary-light: #4895ef;
    --secondary: #3f37c9;
    --success: #4cc9f0;
    --danger: #f72585;
    --warning: #f8961e;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --gray-light: #e9ecef;
    --border-radius: 8px;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f5f7fb;
    color: var(--dark);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    padding: 1.5rem 0;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 10px;
}

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

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background-color: var(--secondary);
    transform: translateY(-2px);
}

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

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

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--primary);
    color: var(--primary);
}

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

.main-content {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 30px;
    margin: 30px 0;
}

.sidebar {
    background-color: white;
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    height: fit-content;
}

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

.search-box input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--gray-light);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

.filter-section {
    margin-bottom: 25px;
}

.filter-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 15px;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 8px;
}

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

.filter-option {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
}

.filter-option input {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.filter-option label {
    cursor: pointer;
    flex: 1;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
}

.course-card {
    background-color: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
    cursor: pointer;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.course-header {
    padding: 20px;
    background: linear-gradient(135deg, var(--primary-light), var(--primary));
    color: white;
    position: relative;
}

.course-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 5px;
}

.course-description {
    font-size: 0.9rem;
    opacity: 0.9;
}

.favorite-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    background: none;
    border: none;
    color: white;
    font-size: 1.2rem;
    cursor: pointer;
    transition: var(--transition);
}

.favorite-btn:hover {
    transform: scale(1.2);
}

.favorite-btn.active {
    color: var(--warning);
}

.course-body {
    padding: 20px;
}

.progress-section {
    margin-bottom: 15px;
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 0.9rem;
}

.progress-bar {
    height: 8px;
    background-color: var(--gray-light);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(to right, var(--success), var(--primary-light));
    border-radius: 4px;
    transition: width 0.5s ease;
}

.course-stats {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--gray);
}

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background-color: white;
    border-radius: var(--border-radius);
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    transform: translateY(-20px);
    transition: var(--transition);
}

.modal-overlay.active .modal {
    transform: translateY(0);
}

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

.modal-title {
    font-size: 1.5rem;
    font-weight: 600;
}

.modal-actions {
    margin-top: 30px;
    text-align: right;
    border-top: 1px solid var(--gray-light);
    padding-top: 20px;
}

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

.btn-danger:hover {
    background-color: #e1156d;
    transform: translateY(-2px);
}

.close-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--gray);
    transition: var(--transition);
}

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

.modal-body {
    padding: 20px;
}

.form-group {
    margin-bottom: 20px;
}

.form-label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

.form-control {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--gray-light);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

.tasks-list {
    margin-top: 20px;
}

.task-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 0;
    border-bottom: 1px solid var(--gray-light);
}

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

.task-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border: 2px solid #ccc;
    border-radius: 3px;
    cursor: pointer;
}

input[type="checkbox"]:checked {
    background-color: #00a6ff;
    border-color: #00a6ff;
}

.task-text {
    flex: 1;
}

.task-actions {
    display: flex;
    gap: 5px;
}

.task-actions button {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--gray);
    transition: var(--transition);
}

.task-actions button:hover {
    color: var(--dark);
}

.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: var(--gray);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 15px;
    opacity: 0.5;
}

@media (max-width: 768px) {
    .main-content {
        grid-template-columns: 1fr;
    }

    .sidebar {
        order: 2;
    }

    .courses-section {
        order: 1;
    }

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