/* 
   Mengatur font dasar dan menghapus jarak (margin) bawaan browser
   Tanda * berarti berlaku untuk semua elemen HTML
*/
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

/* Mengatur warna latar belakang (Dark Mode) dan teks secara keseluruhan */
body {
    background-color: #0f172a;
    /* Warna biru dongker sangat gelap (elegan) */
    color: #f8fafc;
    /* Warna teks putih keabu-abuan agar nyaman di mata */
    line-height: 1.6;
}

/* --- KELAS UTILITAS --- */
/* Ini adalah efek 'Glassmorphism' (kaca buram) yang memberikan kesan premium */
.glass {
    background: rgba(255, 255, 255, 0.03);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 16px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
}

/* --- NAVBAR --- */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 50px;
    position: fixed;
    /* Membuat navbar tetap di atas saat di-scroll */
    top: 0;
    width: 100%;
    z-index: 100;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: #fff;
}

.navbar nav a {
    color: #cbd5e1;
    text-decoration: none;
    margin-left: 30px;
    font-weight: 600;
    transition: color 0.3s ease;
    /* Animasi halus saat warna berubah */
}

.navbar nav a:hover {
    color: #8b5cf6;
    /* Berubah menjadi warna ungu saat cursor diletakkan di atasnya */
}

/* --- HERO SECTION (Bagian Atas) --- */
.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 100vh;
    /* Memenuhi tinggi layar */
    padding: 0 50px;
    padding-top: 80px;
    /* Menghindari konten tertutup oleh navbar */
    /* Memberikan efek cahaya halus di latar belakang */
    background: radial-gradient(circle at 10% 20%, rgba(139, 92, 246, 0.15) 0%, transparent 40%);
}

.hero-content {
    flex: 1;
    max-width: 600px;
}

.badge {
    background: rgba(139, 92, 246, 0.2);
    color: #c4b5fd;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    display: inline-block;
    margin-bottom: 20px;
}

.hero h1 {
    font-size: 4rem;
    line-height: 1.1;
    margin-bottom: 20px;
    font-weight: 800;
}

/* Membuat efek warna gradasi pada teks khusus */
.hero h1 span {
    background: linear-gradient(to right, #8b5cf6, #3b82f6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.2rem;
    color: #94a3b8;
    margin-bottom: 40px;
}

/* --- TOMBOL UTAMA --- */
.btn-primary {
    display: inline-block;
    background: linear-gradient(135deg, #8b5cf6, #6d28d9);
    color: white;
    padding: 15px 35px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    box-shadow: 0 10px 20px rgba(139, 92, 246, 0.3);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.btn-primary:hover {
    transform: translateY(-3px);
    /* Efek tombol terangkat saat disorot */
    box-shadow: 0 15px 25px rgba(139, 92, 246, 0.4);
}

.full-width {
    display: block;
    text-align: center;
    width: 100%;
}

/* --- MOCKUP BUKU 3D --- */
.hero-image {
    flex: 1;
    display: flex;
    justify-content: center;
    perspective: 1000px;
    /* Diperlukan untuk memberi kesan kedalaman (3D) */
}

.book-mockup {
    width: 300px;
    height: 450px;
    background: linear-gradient(135deg, #1e293b, #0f172a);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 10px 20px 20px 10px;
    /* Bentuk sudut seperti buku asli */
    padding: 40px;
    box-shadow: -20px 20px 30px rgba(0, 0, 0, 0.5), inset 4px 0 10px rgba(255, 255, 255, 0.1);
    transform: rotateY(-15deg) rotateX(5deg);
    transition: transform 0.5s ease;
}

.book-mockup:hover {
    transform: rotateY(-5deg) rotateX(0deg);
    /* Animasi interaktif saat disorot */
}

.book-mockup h2 {
    font-size: 2.5rem;
    background: linear-gradient(to bottom right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 20px;
    line-height: 1.2;
}

/* --- FITUR SECTION --- */
.features {
    padding: 100px 50px;
    text-align: center;
}

.features h2 {
    font-size: 2.5rem;
    margin-bottom: 50px;
}

.feature-grid {
    display: grid;
    /* CSS Grid untuk membuat grid yang responsif otomatis */
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.feature-card {
    padding: 40px;
    text-align: left;
    transition: transform 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-10px);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: #e2e8f0;
}

.feature-card p {
    color: #94a3b8;
}

/* --- HARGA SECTION --- */
.pricing {
    padding: 100px 50px;
    display: flex;
    justify-content: center;
    background: radial-gradient(circle at 90% 80%, rgba(59, 130, 246, 0.1) 0%, transparent 40%);
}

.pricing-card {
    padding: 50px;
    max-width: 400px;
    width: 100%;
}

.pricing-card h2 {
    font-size: 2rem;
    margin-bottom: 10px;
}

.price {
    font-size: 3rem;
    font-weight: 800;
    color: #8b5cf6;
    margin-bottom: 30px;
}

.pricing-card ul {
    list-style: none;
    /* Menghilangkan titik (bullet) bawaan dari list */
    margin-bottom: 40px;
}

.pricing-card ul li {
    margin-bottom: 15px;
    color: #cbd5e1;
    font-size: 1.1rem;
}

/* --- FOOTER --- */
footer {
    text-align: center;
    padding: 30px;
    color: #64748b;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    margin-top: 50px;
}

/* --- MEDIA QUERY (Untuk Responsif di Layar HP) --- */
/* Jika ukuran layar lebih kecil dari 768px, jalankan kode ini */
@media (max-width: 768px) {
    .hero {
        flex-direction: column;
        text-align: center;
        padding-top: 120px;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-image {
        margin-top: 50px;
    }

    .book-mockup {
        transform: rotateY(0);
        /* Menghapus efek miring di layar kecil agar pas */
    }
}