:root {
    --primary: #0f172a;
    --secondary: #334155; 
    --accent: #f59e0b;
    --accent-hover: #d97706;
    --bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --text-light: #64748b;
    --border: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius: 12px;
    --transition: all 0.3s ease;
}

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

body {
    background-color: var(--bg);
    color: var(--text);
    overflow-x: hidden;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    background-color: var(--card-bg);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo i {
    color: var(--accent);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

.nav-links li a {
    text-decoration: none;
    color: var(--text-light);
    font-weight: 700;
    font-size: 1.1rem;
    transition: var(--transition);
    padding: 0.5rem;
    position: relative;
}

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

.nav-links li a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    right: 0;
    width: 100%;
    height: 3px;
    background-color: var(--accent);
    border-radius: 3px;
}

.menu-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--primary);
}

.main-content {
    padding: 2rem 5%;
    min-height: calc(100vh - 80px);
}

.page-section {
    display: none;
    animation: fadeIn 0.4s ease-in-out;
}

.page-section.active-section {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}

.hero {
    background: linear-gradient(135deg, var(--primary) 0%, #1e293b 100%);
    border-radius: var(--radius);
    padding: 5rem 2rem;
    text-align: center;
    color: white;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 800;
}

.hero h1 span {
    color: var(--accent);
}

.hero p {
    font-size: 1.3rem;
    color: #cbd5e1;
    margin-bottom: 2rem;
}

.btn {
    padding: 0.8rem 1.8rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 700;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.primary-btn:hover {
    background-color: var(--accent-hover);
    transform: translateY(-3px);
    box-shadow: 0 10px 15px -3px rgba(245, 158, 11, 0.3);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    background: var(--card-bg);
    padding: 2.5rem 1.5rem;
    border-radius: var(--radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.feature-card i {
    font-size: 3rem;
    color: var(--accent);
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    margin-bottom: 0.8rem;
    color: var(--primary);
    font-size: 1.4rem;
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.6;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 2px solid var(--border);
}

.section-header h2 {
    font-size: 2.2rem;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.section-header h2 i {
    color: var(--accent);
}

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

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

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.topic-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    overflow: hidden;
    position: relative;
    cursor: pointer;
    transition: var(--transition);
    border: 1px solid var(--border);
}

.topic-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
}

.thumbnail-wrapper {
    position: relative;
    width: 100%;
    padding-top: 56.25%;
    background-color: #cbd5e1;
    overflow: hidden;
}

.thumbnail-wrapper img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s ease;
}

.topic-card:hover .thumbnail-wrapper img {
    transform: scale(1.08);
}

.placeholder-thumb {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 3.5rem;
    color: #94a3b8;
    background: linear-gradient(135deg, #e2e8f0, #cbd5e1);
}

.card-content {
    padding: 1.2rem;
    position: relative;
}

.card-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 0.8rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.4;
}

.card-meta {
    font-size: 0.95rem;
    color: var(--text-light);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.delete-btn {
    position: absolute;
    bottom: 1.2rem;
    right: 1.2rem;
    background: white;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    border: 1px solid #ef4444;
    color: #ef4444;
    cursor: pointer;
    font-size: 1rem;
    opacity: 0;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.topic-card:hover .delete-btn {
    opacity: 1;
}

.delete-btn:hover {
    background: #ef4444;
    color: white;
    transform: scale(1.1);
}

.modal {
    display: none; 
    position: fixed; 
    z-index: 1000; 
    left: 0;
    top: 0;
    width: 100%; 
    height: 100%; 
    overflow: auto; 
    background-color: rgba(15, 23, 42, 0.7); 
    backdrop-filter: blur(5px);
    justify-content: center;
    align-items: center;
}

.modal.show {
    display: flex;
}

.modal-content {
    background-color: var(--card-bg);
    padding: 2.5rem;
    border-radius: var(--radius);
    width: 90%;
    max-width: 500px;
    position: relative;
    animation: zoomIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: var(--shadow-lg);
}

@keyframes zoomIn {
    from { transform: scale(0.8); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

.close-btn {
    position: absolute;
    top: 1rem;
    right: 1.5rem;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-light);
    transition: color 0.3s;
}

.close-btn:hover {
    color: #ef4444;
}

.modal-header {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 2rem;
    color: var(--primary);
    font-size: 1.4rem;
}

.modal-header i {
    color: var(--accent);
}

.form-group {
    margin-bottom: 1.5rem;
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 0.6rem;
    font-weight: 700;
    color: var(--secondary);
}

.form-group input {
    width: 100%;
    padding: 0.9rem;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    font-family: 'Tajawal', sans-serif;
    outline: none;
    transition: var(--transition);
    background-color: var(--bg);
}

.form-group input:focus {
    border-color: var(--accent);
    background-color: white;
    box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.15);
}

.submit-btn {
    width: 100%;
    justify-content: center;
    padding: 1rem;
    font-size: 1.2rem;
    margin-top: 1rem;
}

.empty-state {
    grid-column: 1 / -1;
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-light);
    background: var(--card-bg);
    border-radius: var(--radius);
    border: 2px dashed var(--border);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: 1.5rem;
    color: #cbd5e1;
}

.empty-state h3 {
    color: var(--secondary);
    margin-bottom: 0.5rem;
    font-size: 1.5rem;
}

@media (max-width: 900px) {
    .nav-links {
        gap: 1rem;
    }
    .nav-links li a {
        font-size: 1rem;
    }
}

@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }

    .nav-links {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--card-bg);
        box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1);
        padding: 1rem;
        gap: 1rem;
        clip-path: polygon(0 0, 100% 0, 100% 0, 0 0);
        transition: clip-path 0.4s ease-in-out;
    }

    .nav-links.show {
        clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
    }
    
    .nav-links li {
        width: 100%;
        text-align: center;
    }

    .hero h1 {
        font-size: 2.2rem;
    }
    
    .section-header {
        flex-direction: column;
        gap: 1.5rem;
        align-items: flex-start;
    }
}