:root {
    --primary-color: #7C3AED;
    --primary-light: #8B5CF6;
    --secondary-color: #F59E0B;
    --background-color: #F3F4F6;
    --card-bg: #FFFFFF;
    --text-main: #1F2937;
    --text-muted: #6B7280;
    --grammar-color: #3B82F6;
    --reading-color: #10B981;
    --grammar-gradient: linear-gradient(135deg, #60A5FA, #3B82F6);
    --reading-gradient: linear-gradient(135deg, #34D399, #10B981);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Tajawal', sans-serif;
}

body {
    background-color: var(--background-color);
    background-image: radial-gradient(#E5E7EB 1px, transparent 1px);
    background-size: 20px 20px;
    color: var(--text-main);
    overflow-x: hidden;
    overflow-y: scroll; /* Force vertical scrollbar to prevent layout shifts/trembling */
}

#app {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    padding: 20px 30px;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.05);
    margin-bottom: 40px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo i {
    font-size: 2rem;
    color: var(--primary-color);
}

.logo h1 {
    font-family: 'Changa', sans-serif;
    color: var(--primary-color);
    font-size: 1.8rem;
}

.subject-badge {
    background: var(--primary-light);
    color: white;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: bold;
    margin-right: 15px;
}

.user-info .stars {
    background: #FEF3C7;
    color: #D97706;
    padding: 10px 20px;
    border-radius: 20px;
    font-weight: bold;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Dashboard */
.welcome-section {
    text-align: center;
    margin-bottom: 40px;
}

.welcome-section h2 {
    font-size: 2.5rem;
    color: var(--text-main);
    margin-bottom: 10px;
}

.welcome-section p {
    font-size: 1.2rem;
    color: var(--text-muted);
}

.books-container {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.book-card {
    background: var(--card-bg);
    border-radius: 30px;
    width: 400px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    box-shadow: 0 15px 35px rgba(0,0,0,0.1);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275), box-shadow 0.3s ease;
}

.book-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 45px rgba(0,0,0,0.15);
}

.book-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: white;
    position: relative;
    z-index: 2;
}

.grammar-book .book-icon {
    background: var(--grammar-gradient);
    box-shadow: 0 10px 20px rgba(59, 130, 246, 0.4);
}

.reading-book .book-icon {
    background: var(--reading-gradient);
    box-shadow: 0 10px 20px rgba(16, 185, 129, 0.4);
}

.book-info {
    position: relative;
    z-index: 2;
}

.book-info h3 {
    font-size: 2rem;
    margin-bottom: 10px;
    font-family: 'Changa', sans-serif;
}

.grammar-book h3 { color: var(--grammar-color); }
.reading-book h3 { color: var(--reading-color); }

.book-info p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

.card-decoration {
    position: absolute;
    top: -50px;
    right: -50px;
    width: 150px;
    height: 150px;
    border-radius: 50%;
    opacity: 0.1;
    z-index: 1;
}

.grammar-book .card-decoration { background: var(--grammar-color); }
.reading-book .card-decoration { background: var(--reading-color); }

/* Lesson Section */
.section-header {
    display: flex;
    align-items: center;
    margin-bottom: 40px;
    gap: 20px;
}

.back-btn {
    background: white;
    border: none;
    padding: 10px 20px;
    border-radius: 15px;
    font-size: 1.1rem;
    cursor: pointer;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: 'Tajawal', sans-serif;
    color: var(--text-main);
    transition: all 0.2s;
}

.back-btn:hover {
    background: var(--primary-light);
    color: white;
    transform: translateX(-5px);
}

.section-header h2 {
    font-size: 2.2rem;
    color: var(--text-main);
    font-family: 'Changa', sans-serif;
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 25px;
}

.lesson-card {
    background: white;
    border-radius: 20px;
    padding: 20px;
    text-align: center;
    box-shadow: 0 10px 20px rgba(0,0,0,0.05);
    cursor: pointer;
    transition: all 0.3s;
    border: 2px solid transparent;
}

.lesson-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary-light);
    box-shadow: 0 15px 25px rgba(139, 92, 246, 0.2);
}

.lesson-emoji-container {
    width: 100%;
    height: 140px;
    background: linear-gradient(135deg, #F0F9FF, #E0F2FE);
    border-radius: 20px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4.5rem;
    box-shadow: inset 0 2px 10px rgba(0,0,0,0.02);
    transition: transform 0.3s ease;
}

.lesson-card:hover .lesson-emoji-container {
    transform: scale(1.1) rotate(5deg);
}

.lesson-card h4 {
    font-size: 1.2rem;
    color: var(--text-main);
}