:root { 
            --navy: #284469; 
            --navy-light: #1e3554;
            --gold: #FEC763; 
            --gold-soft: #fcfaf2;
            --bg: #f4f7f9; 
            --surface: #ffffff;
            --border: #e2e8f0;
            --text-main: #1e293b;
            --text-muted: #64748b;
        }

        * { margin: 0; padding: 0; box-sizing: border-box; }
        body { font-family: 'Inter', sans-serif; background: var(--bg); color: var(--text-main); line-height: 1.6; }

        /* --- ACADEMIC HEADER --- */
        header {
            background: linear-gradient(135deg, var(--navy), var(--navy-light));
            color: white;
            padding: 40px 20px;
            text-align: center;
            border-bottom: 5px solid var(--gold);
            box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        }

        .logo-container { margin-bottom: 15px; }
        .nectar-logo {
            height: 70px; width: auto;
            filter: drop-shadow(0 4px 6px rgba(0,0,0,0.3));
            transition: transform 0.3s ease;
        }
        .nectar-logo:hover { transform: scale(1.05); }

        .academy-logo { 
            font-family: 'Playfair Display', serif; 
            font-size: 2rem; 
            letter-spacing: 1.5px; 
            color: white;
            margin-bottom: 5px;
        }
        .dept-title { font-size: 0.85rem; text-transform: uppercase; letter-spacing: 3px; color: var(--gold); font-weight: 600; }

        .container { max-width: 850px; margin: -30px auto 60px; padding: 0 20px; position: relative; z-index: 10; }

        /* --- CURRICULUM HUB --- */
        .curriculum-hub {
            background: var(--surface);
            padding: 25px;
            border-radius: 12px;
            box-shadow: 0 10px 25px rgba(0,0,0,0.05);
            margin-bottom: 30px;
            border: 1px solid var(--border);
        }

        .hub-title {
            font-family: 'Playfair Display', serif;
            font-size: 1.3rem; color: var(--navy); margin-bottom: 20px;
            display: flex; align-items: center; justify-content: center; gap: 10px;
        }

        .hub-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 12px; }

        .hub-item {
            background: var(--bg);
            padding: 15px 10px;
            border-radius: 8px;
            text-align: center;
            cursor: pointer;
            transition: all 0.2s ease;
            border: 2px solid transparent;
        }

        .hub-item i { font-size: 1.5rem; color: var(--navy-light); margin-bottom: 8px; display: block; }
        .hub-item span { font-size: 0.8rem; font-weight: 700; color: var(--navy); display: block; }
        .hub-item small { font-size: 0.65rem; color: var(--text-muted); font-weight: 600; background: #e2e8f0; padding: 2px 6px; border-radius: 4px; margin-top: 5px; display: inline-block; }
        
        .hub-item:hover { transform: translateY(-3px); box-shadow: 0 5px 15px rgba(0,0,0,0.08); }
        .hub-item.active { border-color: var(--gold); background: var(--gold-soft); }
        .hub-item.active i { color: var(--gold); }

        /* --- GRAMMAR CARD --- */
        #materiDisplay { display: none; }

        .grammar-card {
            background: var(--surface);
            border-radius: 12px;
            border: 1px solid var(--border);
            box-shadow: 0 15px 35px rgba(0,33,71,0.08);
            overflow: hidden;
            animation: fadeInUp 0.5s ease;
        }

                /* --- LEVEL FILTER BUTTONS for GRAMMAR--- */
        .filter-container {
            display: flex;
            justify-content: center;
            gap: 10px;
            margin-bottom: 25px;
            flex-wrap: wrap;
        }
        
        .filter-btn {
            background: var(--bg);
            border: 2px solid var(--border);
            color: var(--text-muted);
            padding: 8px 20px;
            border-radius: 20px;
            font-size: 0.8rem;
            font-weight: 700;
            cursor: pointer;
            transition: all 0.3s ease;
            text-transform: uppercase;
            letter-spacing: 1px;
        }
        
        .filter-btn:hover {
            border-color: var(--gold);
            color: var(--navy);
        }

.filter-btn.active {
    background: var(--navy);
    color: white;
    border-color: var(--navy);
    box-shadow: 0 4px 10px rgba(0, 33, 71, 0.2);
}

        @keyframes fadeInUp {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .card-accent { height: 6px; background: linear-gradient(90deg, var(--navy), var(--gold)); }
        .card-content { padding: 40px; }

        .card-header { 
            display: flex; justify-content: space-between; align-items: flex-start; 
            margin-bottom: 25px; padding-bottom: 20px; border-bottom: 2px solid var(--bg);
        }
        
        .grammar-title { font-family: 'Playfair Display', serif; font-size: 2rem; color: var(--navy); line-height: 1.2; }
        .badge-level { 
            background: var(--navy); color: var(--gold); padding: 6px 12px; 
            font-size: 0.75rem; font-weight: 700; border-radius: 6px; letter-spacing: 1px;
        }

        .section-label { 
            font-weight: 700; color: var(--text-muted); text-transform: uppercase; 
            font-size: 0.75rem; letter-spacing: 1.5px; margin-bottom: 10px; display: block; 
        }

        /* Tampilan Rumus yang Enak Dibaca */
        .formula-box { 
            font-family: 'Inter', monospace; font-size: 1.25rem; color: var(--navy); 
            background: var(--bg); padding: 18px 20px; border-radius: 8px;
            border-left: 5px solid var(--gold); font-weight: 700; margin-bottom: 25px;
            letter-spacing: 0.5px; display: inline-block; width: 100%; text-align: center;
        }

        .explanation-area { margin-bottom: 30px; font-size: 1.05rem; color: var(--text-main); }
        .translation-id { display: none; color: var(--text-muted); font-style: italic; margin-top: 5px; font-size: 0.95rem; background: #f8fafc; padding: 10px; border-radius: 6px; border-left: 3px solid #cbd5e1; }

        /* Layout Contoh Kalimat (Baru) */
        .examples-container {
            background: var(--gold-soft); padding: 20px; border-radius: 8px; margin-bottom: 30px; border: 1px solid #f3e5b4;
        }
        .example-item { margin-bottom: 12px; padding-bottom: 12px; border-bottom: 1px dashed #e2e8f0; }
        .example-item:last-child { margin-bottom: 0; padding-bottom: 0; border-bottom: none; }
        .ex-en { font-weight: 600; color: var(--navy); font-size: 1.1rem; }
        .ex-en i { color: var(--gold); margin-right: 8px; font-size: 0.9rem; }

        /* --- PRACTICE ZONE --- */
        .practice-zone {
            background: #ffffff; border: 2px solid var(--border); border-radius: 10px;
            padding: 30px; position: relative; box-shadow: inset 0 2px 10px rgba(0,0,0,0.02);
        }

        .mission-badge {
            position: absolute; top: -14px; left: 25px;
            background: var(--gold); color: var(--navy); font-size: 0.7rem;
            font-weight: 800; padding: 5px 15px; border-radius: 20px; letter-spacing: 1px;
            box-shadow: 0 4px 6px rgba(197, 160, 33, 0.3);
        }

        .writing-pad {
            width: 100%; border: none; border-bottom: 3px solid #e2e8f0;
            font-size: 1.3rem; padding: 15px 0; color: var(--navy);
            outline: none; transition: 0.3s; background: transparent;
            font-family: 'Playfair Display', serif; margin-bottom: 10px;
        }
        .writing-pad:focus { border-bottom-color: var(--navy); }
        .writing-pad::placeholder { color: #cbd5e1; font-style: italic; }

        .feedback-msg {
            margin-top: 15px; padding: 15px 20px; font-size: 0.95rem; border-radius: 8px;
            display: none; line-height: 1.5; font-weight: 500;
            animation: fadeInUp 0.3s ease;
        }
        .feedback-msg.correct { background: #ecfdf5; color: #065f46; border: 1px solid #a7f3d0; }
        .feedback-msg.wrong { background: #fef2f2; color: #991b1b; border: 1px solid #fecaca; }

        /* --- BUTTONS --- */
        .btn-group { display: flex; gap: 15px; margin-top: 25px; flex-wrap: wrap; }
        .btn {
            flex: 1; min-width: 150px; padding: 14px; border: none; border-radius: 8px; cursor: pointer; font-weight: 700;
            font-size: 0.85rem; text-transform: uppercase; letter-spacing: 1px;
            display: flex; align-items: center; justify-content: center; gap: 10px; transition: all 0.3s ease;
        }
        .btn-navy { background: var(--navy); color: white; box-shadow: 0 4px 10px rgba(0, 33, 71, 0.2); }
        .btn-gold { background: var(--gold); color: var(--navy); box-shadow: 0 4px 10px rgba(197, 160, 33, 0.2); }
        .btn:hover { transform: translateY(-2px); filter: brightness(1.1); }
        .btn:active { transform: translateY(0); }

        @media (max-width: 600px) {
            .card-content { padding: 25px; }
            .grammar-title { font-size: 1.6rem; }
            .formula-box { font-size: 1.1rem; padding: 15px; }
        }
                /* --- QUICK NAVIGATION STYLE --- */
        .quick-nav {
            background: var(--surface);
            border-bottom: 1px solid var(--border);
            padding: 10px 0;
            position: sticky;
            top: 0;
            z-index: 1000;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
        }
        
        .nav-container {
            max-width: 850px;
            margin: 0 auto;
            padding: 0 20px;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .nav-link {
            text-decoration: none;
            color: var(--navy);
            font-weight: 700;
            font-size: 0.85rem;
            text-transform: uppercase;
            display: flex;
            align-items: center;
            gap: 8px;
            transition: 0.3s;
        }
        
        .nav-link:hover {
            color: var(--gold);
        }
        
        .nav-search {
            display: flex;
            align-items: center;
            background: var(--bg);
            padding: 6px 15px;
            border-radius: 20px;
            border: 1px solid var(--border);
            width: 250px;
        }
        
        .nav-search i {
            color: var(--text-muted);
            font-size: 0.8rem;
            margin-right: 10px;
        }
        
        .nav-search input {
            border: none;
            background: transparent;
            outline: none;
            font-size: 0.85rem;
            width: 100%;
            color: var(--text-main);
        }
        
        /* Penyesuaian container agar tidak tertutup nav yang menempel */
        .container { 
            margin-top: 20px !important; 
        }
        
        /* =========================================================
           SINGLE ACADEMIC MATERI CARD (DETAIL DISPLAY)
        ========================================================= */
        #materiDisplay {
            display: none; /* Disembunyikan otomatis sampai murid klik menu */
            margin-top: 45px;
            animation: slideUpFade 0.6s cubic-bezier(0.16, 1, 0.3, 1);
        }
        
        @keyframes slideUpFade {
            from { opacity: 0; transform: translateY(30px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        .grammar-card {
            background: #ffffff;
            border-radius: 12px;
            box-shadow: 0 10px 40px rgba(0, 33, 71, 0.08);
            overflow: hidden;
            position: relative;
            border: 1px solid #e2e8f0;
            max-width: 900px; /* Lebar maksimal agar bacaan tetap terpusat di Desktop */
            margin: 0 auto;
        }
        
        /* Aksen Garis Akademik di Sebelah Kiri */
        .card-accent {
            position: absolute;
            top: 0;
            left: 0;
            width: 6px;
            height: 100%;
            background: linear-gradient(to bottom, var(--navy), var(--gold));
        }
        
        .card-content {
            padding: 45px 50px;
        }
        
        /* Responsif Layar Mobile / Smartphone */
        @media (max-width: 768px) {
            .card-content {
                padding: 30px 20px;
            }
        }
        
        /* --- HEADER KARTU --- */
        .card-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            border-bottom: 2px solid #f1f5f9;
            padding-bottom: 20px;
            margin-bottom: 30px;
            gap: 15px;
            flex-wrap: wrap; 
        }
        
        .grammar-title {
            font-family: 'Playfair Display', serif;
            font-size: 2.2rem;
            color: var(--navy);
            margin: 0;
            font-weight: 800;
            line-height: 1.2;
        }
        
        @media (max-width: 768px) {
            .grammar-title { font-size: 1.8rem; }
        }
        
        .badge-level {
            background: #fcfaf2;
            color: var(--gold);
            border: 1px solid var(--gold);
            padding: 6px 16px;
            border-radius: 8px;
            font-weight: 700;
            font-size: 0.95rem;
            letter-spacing: 1px;
            box-shadow: 0 2px 4px rgba(197, 160, 33, 0.1);
        }
        
        /* --- BAGIAN KONTEN (FORMULA & EXPLANATION) --- */
        .section-label {
            display: flex;
            align-items: center;
            font-size: 0.85rem;
            color: #64748b;
            text-transform: uppercase;
            font-weight: 700;
            letter-spacing: 1.2px;
            margin-bottom: 12px;
            margin-top: 35px;
        }
        
        .section-label i {
            color: var(--gold);
            margin-right: 8px;
            font-size: 1.1rem;
        }
        
        .formula-box {
            background: #f8fafc;
            border-left: 4px solid var(--navy);
            padding: 18px 20px;
            font-family: 'Courier New', Courier, monospace;
            font-size: 1.15rem;
            color: var(--navy);
            font-weight: 700;
            border-radius: 0 8px 8px 0;
            letter-spacing: 0.5px;
        }
        
        .explanation-area {
            font-size: 1.05rem;
            line-height: 1.8;
            color: #334155;
        }
        
        .explanation-area .translation-id {
            color: #64748b;
            background: #fcfaf2;
            padding: 12px 18px;
            border-radius: 6px;
            margin-top: 15px;
            border-left: 3px solid var(--gold);
            font-size: 0.95rem;
        }
        
        /* --- EXAMPLES SECTION --- */
        .examples-container {
            display: flex;
            flex-direction: column;
            gap: 15px;
        }
        
        .example-item {
            background: #ffffff;
            border: 1px solid #e2e8f0;
            padding: 18px 20px;
            border-radius: 8px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.02);
            transition: transform 0.2s;
        }
        
        .example-item:hover {
            transform: translateX(5px);
            border-color: #cbd5e1;
        }
        
        .example-item .ex-en {
            font-weight: 600;
            color: var(--navy);
            font-size: 1.05rem;
            display: flex;
            align-items: flex-start;
            gap: 10px;
        }
        
        .example-item .ex-en i {
            color: #27ae60;
            margin-top: 4px;
        }
        
        .example-item .translation-id {
            color: #64748b;
            font-size: 0.95rem;
        }
        
        /* --- PRACTICE ZONE (DAILY MISSION) --- */
        .practice-zone {
            margin-top: 50px;
            background: linear-gradient(145deg, #f8fafc, #f1f5f9);
            padding: 35px;
            border-radius: 12px;
            border: 1px solid #e2e8f0;
        }
        
        @media (max-width: 768px) {
            .practice-zone { padding: 25px 15px; }
        }
        
        .mission-badge {
            display: inline-block;
            background: var(--navy);
            color: white;
            font-size: 0.75rem;
            font-weight: 700;
            padding: 5px 12px;
            border-radius: 6px;
            letter-spacing: 1.5px;
            margin-bottom: 15px;
            box-shadow: 0 4px 6px rgba(0, 33, 71, 0.2);
        }
        
        .writing-pad {
            width: 100%;
            padding: 16px;
            font-size: 1.05rem;
            border: 2px solid #cbd5e1;
            border-radius: 8px;
            font-family: inherit;
            transition: all 0.3s;
            background: #ffffff;
            color: var(--navy);
        }
        
        .writing-pad:focus {
            outline: none;
            border-color: var(--gold);
            box-shadow: 0 0 0 4px rgba(197, 160, 33, 0.15);
        }
        
        /* Feedback Messages dari JS */
        .feedback-msg {
            margin-top: 15px;
            padding: 14px 18px;
            border-radius: 8px;
            font-size: 0.95rem;
            display: none;
            line-height: 1.5;
        }
        .feedback-msg.correct {
            background: #e8f8f5;
            color: #166534;
            border-left: 4px solid #27ae60;
        }
        .feedback-msg.wrong {
            background: #fffbeb;
            color: #92400e;
            border-left: 4px solid #d97706;
        }
        
        /* --- TOMBOL AKSI --- */
        .btn-group {
            display: flex;
            gap: 15px;
            margin-top: 30px;
        }
        
        .btn {
            flex: 1;
            padding: 14px 20px;
            border: none;
            border-radius: 8px;
            font-weight: 600;
            font-size: 1rem;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            justify-content: center;
            align-items: center;
            gap: 10px;
        }
        
        .btn-navy {
            background: var(--navy);
            color: white;
            box-shadow: 0 4px 10px rgba(0, 33, 71, 0.15);
        }
        .btn-navy:hover {
            background: var(--navy-light);
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(0, 33, 71, 0.25);
        }
        
        .btn-gold {
            background: #fcfaf2;
            color: var(--gold);
            border: 1px solid var(--gold);
        }
        .btn-gold:hover {
            background: var(--gold);
            color: white;
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(197, 160, 33, 0.2);
        }
        
        @media (max-width: 600px) {
            .btn-group { flex-direction: column; }
            .btn { width: 100%; }
        }