:root {
    --bg-app: #0b0f19;
    /* Hitam pekat kebiruan (Deep Space) */
    --bg-card: #161b26;
    /* Hitam abu-abu untuk kotak/card */
    --primary: #c084fc;
    /* Lilac Terang (Warna Utama Aksen) */
    --primary-hover: #a855f7;
    /* Lilac Gelap saat di-hover */
    --success: #34d399;
    /* Hijau Mint untuk tombol sukses */
    --success-hover: #059669;
    --danger: #f87171;
    /* Merah Pastel untuk tombol reset */
    --danger-hover: #dc2626;
    --text-main: #f3f4f6;
    /* Putih terang untuk teks utama */
    --text-muted: #9ca3af;
    /* Abu-abu untuk sub-judul / label */
    --border: #374151;
    /* Garis batas gelap tipis */
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-app);
    color: var(--text-main);
    margin: 0;
    padding: 50px 30px;
    font-size: 16px;
    line-height: 1.6;
}

/* Container Utama */
.container {
    max-width: 1280px;
    /* Sesuai spesifikasi desktop >= 1280px */
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 45px;
}

header h1 {
    font-size: 2.4rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--primary);
    /* Judul menggunakan warna Lilac */
    letter-spacing: -0.5px;
    text-shadow: 0 0 15px rgba(192, 132, 252, 0.3);
    /* Efek glow neon tipis */
}

header p {
    font-size: 1.15rem;
    color: var(--text-muted);
    margin: 0;
}

/* Card Panel dengan Latar Belakang Hitam Elegan */
.card {
    background: var(--bg-card);
    padding: 40px;
    border-radius: 16px;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
    margin-bottom: 40px;
    border: 1px solid var(--border);
    box-sizing: border-box;
    width: 100%;
}

h2 {
    font-size: 1.6rem;
    margin-top: 0;
    border-bottom: 2px solid #2d3748;
    padding-bottom: 18px;
    color: var(--primary);
    /* Sub-judul Lilac */
    margin-bottom: 30px;
    font-weight: 700;
}

h4,
h5 {
    font-size: 1.25rem;
    color: var(--text-main);
    margin-top: 25px;
}

.form-group {
    margin-bottom: 25px;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 12px;
    font-size: 1.1rem;
    color: #e5e7eb;
}

/* Modifikasi Input Field & Select Dropdown */
input[type="text"],
select {
    width: 100%;
    padding: 16px 20px;
    border: 2px solid var(--border);
    border-radius: 10px;
    box-sizing: border-box;
    font-family: 'Courier New', Courier, monospace;
    font-size: 18px;
    font-weight: 700;
    letter-spacing: 1.5px;
    background-color: #1f2937;
    /* Input gelap */
    color: #ffffff;
    transition: all 0.2s ease-in-out;
}

input[type="text"]:focus,
select:focus {
    border-color: var(--primary);
    /* Border berubah jadi Lilac saat diklik */
    background-color: #1f2937;
    box-shadow: 0 0 0 4px rgba(192, 132, 252, 0.25);
    /* Glow Lilac */
    outline: none;
}

/* Dropdown option khusus agar teksnya terlihat di tema gelap */
select option {
    background-color: var(--bg-card);
    color: #ffffff;
}

/* Radio Button Enkripsi / Dekripsi */
.radio-group {
    display: flex;
    gap: 30px;
    padding: 5px 0;
}

.radio-group label {
    display: inline-flex;
    align-items: center;
    margin: 0;
    font-weight: 600;
    font-size: 1.15rem;
    cursor: pointer;
    color: var(--text-main);
}

.radio-group input[type="radio"] {
    transform: scale(1.4);
    margin-right: 12px;
    cursor: pointer;
    accent-color: var(--primary);
    /* Mengubah warna bulatan radio menjadi Lilac */
}

/* Grup Tombol Aksi */
.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 35px;
    border-top: 2px solid #2d3748;
    padding-top: 25px;
}

.btn {
    flex: 1;
    min-width: 180px;
    padding: 16px 32px;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
}

/* Tombol Proses Utama dengan nuansa Lilac */
.btn-primary {
    background: var(--primary);
    color: #0f172a;
    /* Teks gelap di atas tombol terang */
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    color: #ffffff;
}

.btn-success {
    background: var(--success);
    color: #0f172a;
}

.btn-success:hover {
    background: var(--success-hover);
    transform: translateY(-2px);
    color: white;
}

.btn-danger {
    background: transparent;
    border: 2px solid var(--danger);
    color: var(--danger);
    box-shadow: none;
}

.btn-danger:hover {
    background: var(--danger);
    color: #0f172a;
    transform: translateY(-2px);
}

.hidden {
    display: none !important;
}

/* Box Teks Kode Biner / Langkah Perhitungan */
.code-text {
    font-family: 'Courier New', Courier, monospace;
    background: #1f2937;
    padding: 8px 14px;
    border-radius: 8px;
    word-break: break-all;
    display: inline-block;
    font-size: 16px;
    font-weight: 700;
    letter-spacing: 1px;
    color: #e5e7eb;
    border: 1px solid var(--border);
}

.output-box p {
    font-size: 1.2rem;
    margin-bottom: 25px;
}

/* Badge Output Hasil Akhir (Hex) */
.badge {
    background: rgba(192, 132, 252, 0.1);
    /* Transparan Lilac */
    color: var(--primary);
    font-family: 'Courier New', Courier, monospace;
    font-size: 24px;
    font-weight: 800;
    padding: 10px 24px;
    border-radius: 8px;
    border: 2px solid var(--primary);
    letter-spacing: 2px;
    display: inline-block;
    text-shadow: 0 0 10px rgba(192, 132, 252, 0.2);
}

/* Tabel Key Schedule versi Dark */
.table-wrapper {
    overflow-x: auto;
    margin-top: 25px;
    border-radius: 10px;
    border: 1px solid var(--border);
    background: #111827;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-family: 'Courier New', Courier, monospace;
    font-size: 16px;
    color: #e5e7eb;
}

th,
td {
    border: 1px solid var(--border);
    padding: 16px 18px;
    text-align: left;
}

th {
    background: #1f2937;
    color: var(--primary);
    /* Header tabel berwarna Lilac */
    font-family: 'Segoe UI', sans-serif;
    font-weight: 700;
    font-size: 15px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

tr:hover {
    background-color: #1f2937;
}

/* Accordion 16 Putaran */
.round-box {
    border: 2px solid var(--border);
    border-radius: 10px;
    margin-bottom: 20px;
    background: var(--bg-card);
    overflow: hidden;
}

.round-header {
    background: #1f2937;
    padding: 18px 24px;
    font-size: 1.2rem;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.2s;
    color: #e5e7eb;
    border-bottom: 1px solid var(--border);
}

.round-header:hover {
    background: #2563eb;
    /* Transisi warna atau tetap gelap */
    background: rgba(192, 132, 252, 0.15);
    color: var(--primary);
}

.round-body {
    padding: 30px;
    background: #111827;
    /* Isi dalam accordion dibuat lebih gelap */
}

/* Grid Box untuk 8 S-Box */
.sbox-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.sbox-card {
    background: var(--bg-card);
    border: 2px solid var(--border);
    padding: 18px;
    border-radius: 8px;
    font-size: 15px;
    line-height: 1.7;
    color: #d1d5db;
}

.sbox-card strong {
    color: var(--primary);
    /* Output biner S-box disorot Lilac */
    font-size: 16px;
}

hr {
    border: 0;
    border-top: 2px solid var(--border);
    margin: 20px 0;
}

/* (Semua kode CSS yang kamu kirim sebelumnya, masukkan kembali di sini) */
/* ... tambahkan kode ini di paling bawah file ... */

@media screen and (max-width: 768px) {
    body {
        padding: 15px 10px;
    }

    header h1 {
        font-size: 1.8rem;
    }

    .btn-group {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .table-wrapper {
        overflow-x: auto;
        display: block;
    }

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

    .badge {
        font-size: 18px;
        padding: 8px 16px;
    }
}