:root {
    --nav-green: #1B5E20;
    --nav-light: #C8E6C9;
    --nav-active: #2E7D32;
    --primary-green: #2E7D32;
    --light-green: #E8F5E9;
    --earth-brown: #795548;
    --wheat-color: #F5DEB3;
    --sky-blue: #E3F2FD;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

/* Rest of the styles identical to class9.css */ 
/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Subject Tabs */
.subject-tabs {
    background: white;
    padding: 20px 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
    text-align: center;
}

.tab-btn {
    background: none;
    border: none;
    padding: 12px 24px;
    margin: 0 8px;
    font-size: 16px;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    color: var(--earth-brown);
}

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

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

/* Subject Content */
.subject-content {
    display: none;
    padding: 40px 0;
}

.subject-content.active {
    display: block;
}

.subject-header {
    text-align: center;
    margin-bottom: 40px;
}

.subject-header h2 {
    color: var(--primary-green);
    font-size: 32px;
    margin-bottom: 12px;
}

.subject-header p {
    color: var(--earth-brown);
    font-size: 18px;
}

/* Experiments Grid */
.experiments-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.experiment-card {
    background: white;
    border-radius: 16px;
    padding: 24px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease;
    border: 1px solid #eee;
    display: flex;
    flex-direction: column;
}

.experiment-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(46, 125, 50, 0.15);
}

.experiment-header {
    display: flex;
    align-items: center;
    margin-bottom: 16px;
}

.experiment-icon {
    font-size: 24px;
    margin-right: 12px;
}

.experiment-number {
    color: var(--primary-green);
    font-weight: 500;
}

.experiment-card h3 {
    font-size: 20px;
    color: var(--primary-green);
    margin-bottom: 12px;
}

.experiment-card p {
    color: var(--earth-brown);
    margin-bottom: 0;
    line-height: 1.5;
    flex-grow: 1;
}

/* Experiment Meta */
.experiment-meta {
    display: flex;
    gap: 16px;
    margin-bottom: 20px;
    color: var(--earth-brown);
    font-size: 14px;
}

.duration, .difficulty {
    display: flex;
    align-items: center;
    gap: 6px;
}

/* Action Buttons */
.experiment-actions {
    display: flex;
    gap: 12px;
}

.btn-primary, .btn-secondary {
    padding: 12px 20px;
    border-radius: 8px;
    text-decoration: none;
    text-align: center;
    flex: 1;
    transition: all 0.3s ease;
}

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

.btn-primary:hover {
    background: #1B5E20;
}

.btn-secondary {
    background: var(--light-green);
    color: var(--primary-green);
    border: 1px solid var(--primary-green);
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .subject-tabs {
        padding: 16px;
        overflow-x: auto;
        white-space: nowrap;
    }

    .tab-btn {
        padding: 10px 20px;
        margin: 0 4px;
    }

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

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

/* Navigation Styles */
.top-nav {
    background: var(--nav-green);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.15);
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 20px;
    font-weight: 600;
    color: white;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-links {
    display: flex;
    gap: 24px;
    align-items: center;
}

.nav-links a {
    text-decoration: none;
    color: rgba(255, 255, 255, 0.9);
    font-size: 16px;
    padding: 8px 16px;
    border-radius: 20px;
    transition: all 0.3s ease;
}

.nav-links a:hover {
    background: rgba(255, 255, 255, 0.1);
    color: white;
}

.nav-links a.active {
    background: white;
    color: var(--nav-green);
    font-weight: 500;
}

/* Responsive Navigation */
@media (max-width: 768px) {
    .nav-content {
        flex-direction: column;
        gap: 16px;
    }

    .nav-links {
        overflow-x: auto;
        width: 100%;
        padding-bottom: 8px;
        justify-content: flex-start;
    }

    .nav-links::-webkit-scrollbar {
        height: 3px;
    }

    .nav-links::-webkit-scrollbar-thumb {
        background: rgba(255, 255, 255, 0.3);
        border-radius: 3px;
    }
} 

/* Add these button styles to your existing CSS */
.button-group {
    display: flex;
    margin-top: 10px;
    gap: 12px;
}

.btn {
    padding: 12px 20px;
    border-radius: 8px;
    text-decoration: none;
    text-align: center;
    flex: 1;
    transition: all 0.3s ease;
}

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

.btn:hover {
    background: #1B5E20;
}

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

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

/* Add this media query for responsive buttons */
@media (max-width: 768px) {
    .button-group {
        flex-direction: column;
    }
}