:root {
    /* Color Palette */
    --primary-color: #2563eb; /* Blue for Math */
    --secondary-color: #16a34a; /* Green for SVT */
    --accent-color: #ea580c; /* Orange for Physics */
    --background-color: #f8fafc;
    --surface-color: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: 'Tajawal', 'Cairo', sans-serif;
    background-color: --background-color;
    color: var(--text-primary);
    line-height: 1.6;
    direction: rtl; /* Arabic layout */
    text-align: right;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s;
}

ul {
    list-style: none;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

/* Utility Classes */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
}

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

.btn-primary:hover {
    background-color: #1d4ed8;
}

.section {
    padding: var(--spacing-xl) 0;
}

.grid {
    display: grid;
    gap: var(--spacing-md);
}

@media (min-width: 768px) {
    .grid-2 { grid-template-columns: repeat(2, 1fr); }
    .grid-3 { grid-template-columns: repeat(3, 1fr); }
    .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* Header & Navigation */
header {
    background-color: var(--surface-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: var(--spacing-md);
}

.nav-links a {
    font-weight: 500;
    color: var(--text-secondary);
}

.nav-links a:hover, .nav-links a.active {
    color: var(--primary-color);
}

/* Mobile Menu */
.menu-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background-color: var(--surface-color);
        flex-direction: column;
        padding: var(--spacing-md);
        box-shadow: var(--shadow-md);
    }

    .nav-links.active {
        display: flex;
    }

    .menu-toggle {
        display: block;
    }
}

/* Footer */
footer {
    background-color: #1e293b;
    color: white;
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-xl);
}

.footer-content {
    display: grid;
    gap: var(--spacing-lg);
}

.footer-section h3 {
    color: white;
    margin-bottom: var(--spacing-md);
}

.footer-links li {
    margin-bottom: var(--spacing-xs);
}

.footer-links a:hover {
    color: var(--primary-color);
}