/* Course page specific styles */
.course-main {
    min-height: calc(100vh - 200px);
    padding: 40px 0;
}

.course-header {
    margin-bottom: 40px;
    padding-bottom: 30px;
    border-bottom: 1px solid #e0e0e0;
}

.back-link {
    display: inline-flex;
    align-items: center;
    color: var(--green-theme-color);
    text-decoration: none;
    margin-bottom: 20px;
    font-weight: 500;
    transition: color 0.2s;
}

.back-link:hover {
    color: var(--green-theme-color-dark);
}

.course-header h1 {
    margin: 0 0 20px 0;
    color: var(--primary-text-color);
    font-size: 2.5rem;
}

/* Progress bar */
.course-progress {
    display: flex;
    align-items: center;
    gap: 15px;
    max-width: 500px;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: #e0e0e0;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--green-theme-color) 0%, #3bc248 100%);
    border-radius: 4px;
    transition: width 0.4s ease;
    width: 0%;
}

.progress-text {
    font-size: 0.95rem;
    color: var(--secondary-text-color);
    font-weight: 500;
    white-space: nowrap;
}

/* Course layout */
.course-layout {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 40px;
    align-items: start;
}

/* Sidebar */
.course-sidebar {
    position: sticky;
    top: 20px;
    background: white;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    border: 1px solid #f0f0f0;
}

.course-sidebar h3 {
    margin-bottom: 20px;
    color: var(--primary-text-color);
    font-size: 1.2rem;
    border-bottom: 2px solid var(--green-theme-color);
    padding-bottom: 10px;
}

.lesson-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.lesson-item {
    padding: 12px 15px;
    margin-bottom: 8px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    border: 1px solid transparent;
    position: relative;
}

.lesson-item:hover {
    background: rgba(70, 215, 84, 0.05);
    border-color: rgba(70, 215, 84, 0.2);
}

.lesson-item.active {
    background: var(--green-theme-color);
    color: white;
    border-color: var(--green-theme-color);
}

.lesson-item.completed {
    background: rgba(70, 215, 84, 0.1);
    border-color: var(--green-theme-color);
}

.lesson-item.completed::after {
    content: "✓";
    position: absolute;
    right: 12px;
    color: var(--green-theme-color);
    font-weight: bold;
}

.lesson-item.active.completed::after {
    color: white;
}

.lesson-number {
    font-size: 0.85rem;
    opacity: 0.8;
    display: block;
}

.lesson-title {
    font-weight: 500;
    margin-top: 4px;
}

/* Main content */
.course-content {
    background: white;
    border-radius: 12px;
    padding: 40px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    border: 1px solid #f0f0f0;
    min-height: 600px;
}

.lesson-content {
    min-height: 500px;
    line-height: 1.7;
}

.lesson-content h2 {
    color: var(--primary-text-color);
    margin-bottom: 20px;
    font-size: 1.8rem;
}

.lesson-content h3 {
    color: var(--primary-text-color);
    margin: 25px 0 15px 0;
    font-size: 1.3rem;
}

.lesson-content p {
    margin-bottom: 18px;
    color: var(--secondary-text-color);
    font-size: 1.05rem;
}

.lesson-content ul {
    margin: 20px 0;
    padding-left: 25px;
}

.lesson-content li {
    margin-bottom: 10px;
    color: var(--secondary-text-color);
    line-height: 1.6;
}

.lesson-content strong {
    color: var(--primary-text-color);
}

.lesson-image {
    width: 100%;
    max-width: 500px;
    height: 280px;
    object-fit: cover;
    border-radius: 12px;
    margin: 25px 0;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.tip-box {
    background: linear-gradient(135deg, rgba(70, 215, 84, 0.1) 0%, rgba(59, 194, 72, 0.05) 100%);
    border-left: 4px solid var(--green-theme-color);
    padding: 20px 25px;
    margin: 25px 0;
    border-radius: 0 8px 8px 0;
    position: relative;
}

.tip-box h4 {
    color: var(--green-theme-color);
    margin-bottom: 10px;
    font-size: 1.1rem;
}

.tip-box p {
    margin-bottom: 0;
    color: var(--primary-text-color);
}

/* Navigation */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 30px;
    margin-top: 30px;
    border-top: 1px solid #e0e0e0;
}

.nav-btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 0.95rem;
}

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

.nav-btn.primary:hover:not(:disabled) {
    background: var(--green-theme-color-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(70, 215, 84, 0.3);
}

.nav-btn.secondary {
    background: transparent;
    color: var(--secondary-text-color);
    border: 2px solid #e0e0e0;
}

.nav-btn.secondary:hover:not(:disabled) {
    border-color: var(--green-theme-color);
    color: var(--green-theme-color);
}

.nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.lesson-counter {
    font-weight: 600;
    color: var(--primary-text-color);
    background: rgba(70, 215, 84, 0.1);
    padding: 8px 16px;
    border-radius: 20px;
}

/* Responsive design */
@media (max-width: 1024px) {
    .course-layout {
        grid-template-columns: 250px 1fr;
        gap: 30px;
    }
    
    .course-content {
        padding: 30px;
    }
}

@media (max-width: 768px) {
    .course-layout {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .course-sidebar {
        position: static;
        order: 2;
        margin-top: 20px;
    }
    
    .course-content {
        padding: 25px;
        order: 1;
    }
    
    .course-header h1 {
        font-size: 2rem;
    }
    
    .lesson-navigation {
        flex-direction: column;
        gap: 15px;
    }
    
    .nav-btn {
        width: 100%;
        max-width: 200px;
    }
}

@media (max-width: 480px) {
    .course-main {
        padding: 20px 0;
    }
    
    .course-header {
        margin-bottom: 25px;
    }
    
    .course-content {
        padding: 20px;
    }
    
    .course-progress {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .progress-bar {
        width: 100%;
    }
}

/* Loading states */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 60px;
    color: var(--secondary-text-color);
}

.fade-in {
    animation: fadeIn 0.4s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Course button in education page */
.course-btn {
    margin-top: 20px;
    background: var(--green-theme-color);
    color: white !important;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 500;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
}

.course-btn:hover {
    background: var(--green-theme-color-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(70, 215, 84, 0.3);
    color: white !important;
}