/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #334155 100%);
    color: white;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow-x: hidden;
}

/* ===== BACKGROUND EDUCATIONAL ICONS ===== */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><g fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="1"><circle cx="20" cy="20" r="2"/><path d="M10 40 L30 40 M20 35 L20 45"/><circle cx="80" cy="20" r="5" fill="rgba(255,255,255,0.03)"/><path d="M60 60 Q70 50 80 60 Q70 70 60 60"/><circle cx="15" cy="80" r="3"/><path d="M70 80 L90 80 M80 75 L80 85"/></g></svg>');
    background-size: 200px 200px;
    background-repeat: repeat;
    animation: float 20s ease-in-out infinite;
    z-index: -1;
}

/* ===== ANIMATIONS ===== */
@keyframes float {

    0%,
    100% {
        transform: translateY(0px) rotate(0deg);
    }

    50% {
        transform: translateY(-20px) rotate(5deg);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.05);
    }
}

@keyframes ripple {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

/* ===== LAYOUT CONTAINER ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

/* ===== HEADER STYLES ===== */
.main-header {
    text-align: center;
    margin-bottom: 60px;
    position: relative;
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-bottom: 20px;
}

.logo {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #6366f1, #8b5cf6);
    border-radius: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    box-shadow: 0 10px 30px rgba(99, 102, 241, 0.3);
}

.brand-name {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #60a5fa, #a78bfa, #f472b6);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px rgba(96, 165, 250, 0.5);
}

.main-header h1 {
    font-size: 3rem;
    font-weight: 600;
    color: #f1f5f9;
    margin-bottom: 15px;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    line-height: 1.2;
}

.main-header p {
    font-size: 1.3rem;
    color: #cbd5e1;
    font-weight: 300;
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.6;
}

.cta-section {
    margin: 40px 0;
}

.btn-mulai {
    background: linear-gradient(135deg, #6366f1, #8b5cf6, #ec4899);
    color: white;
    padding: 20px 50px;
    font-size: 1.4rem;
    font-weight: 600;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    position: relative;
    overflow: hidden;
    box-shadow: 0 15px 35px rgba(99, 102, 241, 0.4);
    transition: all 0.3s ease;
    text-align: center;
    min-width: 280px;
}

.btn-mulai::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn-mulai:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 20px 40px rgba(99, 102, 241, 0.6);
}

.btn-mulai:hover::before {
    left: 100%;
}

.btn-mulai:active {
    transform: translateY(-1px) scale(1.02);
}

/* ===== FEATURES SECTION ===== */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin: 60px 0;
    width: 100%;
}

.feature-card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 30px;
    text-align: center;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, #6366f1, #8b5cf6, #ec4899);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-10px);
    background: rgba(255, 255, 255, 0.08);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    display: block;
}

.feature-card h3 {
    font-size: 1.4rem;
    font-weight: 600;
    margin-bottom: 15px;
    color: #f1f5f9;
}

.feature-card p {
    color: #cbd5e1;
    line-height: 1.6;
    font-size: 1rem;
}

/* ===== FOOTER STYLES ===== */
.main-footer {
    margin-top: auto;
    padding: 30px 0;
    text-align: center;
    background: rgba(0, 0, 0, 0.2);
    backdrop-filter: blur(10px);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.main-footer p {
    color: #94a3b8;
    font-size: 0.95rem;
    font-weight: 300;
}

/* ===== QUIZ STYLES (untuk halaman quiz) ===== */
#quiz-container {
    max-width: 600px;
    margin: auto;
    padding: 40px;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 25px;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.15);
    color: #1e293b;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

#question-box {
    font-size: 1.4rem;
    margin-bottom: 30px;
    font-weight: 500;
    line-height: 1.5;
}

#answers-box button {
    display: block;
    width: 100%;
    margin: 15px 0;
    padding: 15px 20px;
    font-size: 1.1rem;
    border: 2px solid #e2e8f0;
    border-radius: 15px;
    background-color: #f8fafc;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
    text-align: left;
}

#answers-box button:hover {
    background-color: #f1f5f9;
    border-color: #6366f1;
    transform: translateX(5px);
}

#answers-box button.correct {
    background-color: #10b981;
    color: white;
    border-color: #059669;
}

#answers-box button.wrong {
    background-color: #ef4444;
    color: white;
    border-color: #dc2626;
}

#next-btn {
    margin-top: 30px;
    padding: 15px 30px;
    font-size: 1.1rem;
    background: linear-gradient(135deg, #6366f1, #8b5cf6);
    color: white;
    border: none;
    border-radius: 15px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

#next-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
}

#score-box {
    font-size: 1.6rem;
    margin-top: 40px;
    font-weight: 600;
}

/* ===== ANIMATION CLASSES ===== */
.fade-in-up {
    animation: fadeInUp 0.8s ease-out;
}

.pulse {
    animation: pulse 2s infinite;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    .main-header h1 {
        font-size: 2.2rem;
    }

    .main-header p {
        font-size: 1.1rem;
    }

    .btn-mulai {
        padding: 18px 40px;
        font-size: 1.2rem;
        min-width: 250px;
    }

    .features {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .feature-card {
        padding: 25px;
    }

    #quiz-container {
        padding: 30px 20px;
        margin: 20px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .main-header h1 {
        font-size: 1.8rem;
    }

    .brand-name {
        font-size: 2rem;
    }

    .btn-mulai {
        padding: 15px 30px;
        font-size: 1.1rem;
        min-width: 220px;
    }

    /* ===== RESET & BASE STYLES ===== */
    * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
    }

    body {
        font-family: 'Poppins', sans-serif;
        background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #334155 100%);
        color: white;
        min-height: 100vh;
        display: flex;
        flex-direction: column;
        position: relative;
        overflow-x: hidden;
    }

    /* ===== BACKGROUND EDUCATIONAL ICONS ===== */
    body::before {
        content: '';
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><g fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="1"><circle cx="20" cy="20" r="2"/><path d="M10 40 L30 40 M20 35 L20 45"/><circle cx="80" cy="20" r="5" fill="rgba(255,255,255,0.03)"/><path d="M60 60 Q70 50 80 60 Q70 70 60 60"/><circle cx="15" cy="80" r="3"/><path d="M70 80 L90 80 M80 75 L80 85"/></g></svg>');
        background-size: 200px 200px;
        background-repeat: repeat;
        animation: float 20s ease-in-out infinite;
        z-index: -1;
    }

    /* ===== ANIMATIONS ===== */
    @keyframes float {

        0%,
        100% {
            transform: translateY(0px) rotate(0deg);
        }

        50% {
            transform: translateY(-20px) rotate(5deg);
        }
    }

    @keyframes fadeInUp {
        from {
            opacity: 0;
            transform: translateY(30px);
        }

        to {
            opacity: 1;
            transform: translateY(0);
        }
    }

    @keyframes pulse {

        0%,
        100% {
            transform: scale(1);
        }

        50% {
            transform: scale(1.05);
        }
    }

    @keyframes ripple {
        to {
            transform: scale(4);
            opacity: 0;
        }
    }

    @keyframes slideIn {
        from {
            opacity: 0;
            transform: translateY(20px);
        }

        to {
            opacity: 1;
            transform: translateY(0);
        }
    }

    /* ===== LAYOUT CONTAINER ===== */
    .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
        flex-grow: 1;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
    }

    /* ===== HEADER STYLES ===== */
    .main-header {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .logo-container {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 15px;
        margin-bottom: 20px;
    }

    .logo {
        width: 60px;
        height: 60px;
        background: linear-gradient(135deg, #6366f1, #8b5cf6);
        border-radius: 15px;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 2rem;
        box-shadow: 0 10px 30px rgba(99, 102, 241, 0.3);
    }

    .brand-name {
        font-size: 2.5rem;
        font-weight: 700;
        background: linear-gradient(135deg, #60a5fa, #a78bfa, #f472b6);
        background-clip: text;
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        text-shadow: 0 0 30px rgba(96, 165, 250, 0.5);
    }

    .main-header h1 {
        font-size: 3rem;
        font-weight: 600;
        color: #f1f5f9;
        margin-bottom: 15px;
        text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
        line-height: 1.2;
    }

    .main-header p {
        font-size: 1.3rem;
        color: #cbd5e1;
        font-weight: 300;
        max-width: 600px;
        margin: 0 auto;
        line-height: 1.6;
    }

    /* ===== NAVIGATION CARDS ===== */
    .navigation-section {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 30px;
        margin: 40px 0;
        width: 100%;
    }

    .nav-card {
        background: rgba(255, 255, 255, 0.05);
        backdrop-filter: blur(10px);
        border: 1px solid rgba(255, 255, 255, 0.1);
        border-radius: 20px;
        padding: 40px 30px;
        text-align: center;
        cursor: pointer;
        transition: all 0.3s ease;
        position: relative;
        overflow: hidden;
    }

    .nav-card::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        height: 3px;
        background: linear-gradient(90deg, #6366f1, #8b5cf6, #ec4899);
        transform: scaleX(0);
        transition: transform 0.3s ease;
    }

    .nav-card:hover {
        transform: translateY(-10px);
        background: rgba(255, 255, 255, 0.08);
        box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
    }

    .nav-card:hover::before {
        transform: scaleX(1);
    }

    .nav-icon {
        font-size: 3.5rem;
        margin-bottom: 20px;
        display: block;
    }

    .nav-card h3 {
        font-size: 1.5rem;
        font-weight: 600;
        margin-bottom: 15px;
        color: #f1f5f9;
    }

    .nav-card p {
        color: #cbd5e1;
        line-height: 1.6;
        font-size: 1rem;
    }

    /* ===== MATERIALS SECTION ===== */
    .materials-section {
        width: 100%;
        animation: slideIn 0.5s ease-out;
    }

    .section-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        margin-bottom: 40px;
        flex-wrap: wrap;
        gap: 20px;
    }

    .section-header h2 {
        font-size: 2.2rem;
        font-weight: 600;
        color: #f1f5f9;
        background: linear-gradient(135deg, #60a5fa, #a78bfa);
        background-clip: text;
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
    }

    .btn-back {
        background: rgba(255, 255, 255, 0.1);
        border: 1px solid rgba(255, 255, 255, 0.2);
        color: white;
        padding: 12px 24px;
        border-radius: 12px;
        cursor: pointer;
        font-size: 1rem;
        font-weight: 500;
        transition: all 0.3s ease;
        backdrop-filter: blur(10px);
    }

    .btn-back:hover {
        background: rgba(255, 255, 255, 0.15);
        transform: translateX(-3px);
    }

    .materials-grid {
        display: grid;
        gap: 40px;
    }

    .material-category {
        background: rgba(255, 255, 255, 0.05);
        backdrop-filter: blur(15px);
        border: 1px solid rgba(255, 255, 255, 0.1);
        border-radius: 20px;
        padding: 30px;
        transition: all 0.3s ease;
    }

    .material-category:hover {
        background: rgba(255, 255, 255, 0.08);
        transform: translateY(-5px);
    }

    .material-category h3 {
        font-size: 1.8rem;
        font-weight: 600;
        color: #f1f5f9;
        margin-bottom: 25px;
        border-bottom: 2px solid rgba(255, 255, 255, 0.1);
        padding-bottom: 15px;
    }

    .material-list {
        display: grid;
        gap: 15px;
    }

    .material-item {
        display: flex;
        align-items: center;
        gap: 20px;
        padding: 20px;
        background: rgba(255, 255, 255, 0.03);
        border: 1px solid rgba(255, 255, 255, 0.08);
        border-radius: 15px;
        cursor: pointer;
        transition: all 0.3s ease;
        position: relative;
        overflow: hidden;
    }

    .material-item::before {
        content: '';
        position: absolute;
        left: 0;
        top: 0;
        bottom: 0;
        width: 4px;
        background: linear-gradient(135deg, #6366f1, #8b5cf6);
        transform: scaleY(0);
        transition: transform 0.3s ease;
    }

    .material-item:hover {
        background: rgba(255, 255, 255, 0.08);
        transform: translateX(10px);
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    }

    .material-item:hover::before {
        transform: scaleY(1);
    }

    .material-icon {
        font-size: 2.5rem;
        flex-shrink: 0;
    }

    .material-info {
        flex-grow: 1;
    }

    .material-info h4 {
        font-size: 1.3rem;
        font-weight: 600;
        color: #f1f5f9;
        margin-bottom: 8px;
    }

    .material-info p {
        color: #cbd5e1;
        font-size: 0.95rem;
        line-height: 1.5;
        margin-bottom: 10px;
    }

    .difficulty {
        display: inline-block;
        padding: 4px 12px;
        border-radius: 20px;
        font-size: 0.8rem;
        font-weight: 500;
        text-transform: uppercase;
        letter-spacing: 0.5px;
    }

    .difficulty.easy {
        background: rgba(34, 197, 94, 0.2);
        color: #4ade80;
        border: 1px solid rgba(34, 197, 94, 0.3);
    }

    .difficulty.medium {
        background: rgba(251, 191, 36, 0.2);
        color: #fbbf24;
        border: 1px solid rgba(251, 191, 36, 0.3);
    }

    .difficulty.hard {
        background: rgba(239, 68, 68, 0.2);
        color: #f87171;
        border: 1px solid rgba(239, 68, 68, 0.3);
    }

    /* ===== MODAL STYLES ===== */
    .modal {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.8);
        backdrop-filter: blur(10px);
        display: flex;
        align-items: center;
        justify-content: center;
        z-index: 1000;
        animation: fadeInUp 0.3s ease-out;
    }

    .modal-content {
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        border-radius: 20px;
        max-width: 800px;
        width: 90%;
        max-height: 80vh;
        overflow-y: auto;
        box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
        border: 1px solid rgba(255, 255, 255, 0.2);
        color: #1e293b;
    }

    .modal-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 30px 30px 20px;
        border-bottom: 1px solid rgba(0, 0, 0, 0.1);
    }

    .modal-header h2 {
        font-size: 1.8rem;
        font-weight: 600;
        color: #1e293b;
    }

    .close-btn {
        background: none;
        border: none;
        font-size: 2rem;
        cursor: pointer;
        color: #64748b;
        transition: color 0.3s ease;
        padding: 5px;
        line-height: 1;
    }

    .close-btn:hover {
        color: #1e293b;
    }

    .modal-body {
        padding: 30px;
    }

    .modal-footer {
        display: flex;
        gap: 15px;
        padding: 20px 30px 30px;
        justify-content: flex-end;
    }

    .btn-primary {
        background: linear-gradient(135deg, #6366f1, #8b5cf6);
        color: white;
        border: none;
        padding: 12px 24px;
        border-radius: 12px;
        font-size: 1rem;
        font-weight: 500;
        cursor: pointer;
        transition: all 0.3s ease;
    }

    .btn-primary:hover {
        transform: translateY(-2px);
        box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
    }

    .btn-secondary {
        background: rgba(100, 116, 139, 0.1);
        color: #475569;
        border: 1px solid rgba(100, 116, 139, 0.2);
        padding: 12px 24px;
        border-radius: 12px;
        font-size: 1rem;
        font-weight: 500;
        cursor: pointer;
        transition: all 0.3s ease;
    }

    .btn-secondary:hover {
        background: rgba(100, 116, 139, 0.15);
    }

    /* ===== CTA BUTTON STYLES ===== */
    .cta-section {
        margin: 40px 0;
    }

    .btn-mulai {
        background: linear-gradient(135deg, #6366f1, #8b5cf6, #ec4899);
        color: white;
        padding: 20px 50px;
        font-size: 1.4rem;
        font-weight: 600;
        border: none;
        border-radius: 50px;
        cursor: pointer;
        text-decoration: none;
        display: inline-block;
        position: relative;
        overflow: hidden;
        box-shadow: 0 15px 35px rgba(99, 102, 241, 0.4);
        transition: all 0.3s ease;
        text-align: center;
        min-width: 280px;
    }

    .btn-mulai::before {
        content: '';
        position: absolute;
        top: 0;
        left: -100%;
        width: 100%;
        height: 100%;
        background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
        transition: left 0.5s;
    }

    .btn-mulai:hover {
        transform: translateY(-3px) scale(1.05);
        box-shadow: 0 20px 40px rgba(99, 102, 241, 0.6);
    }

    .btn-mulai:hover::before {
        left: 100%;
    }

    .btn-mulai:active {
        transform: translateY(-1px) scale(1.02);
    }

    /* ===== FEATURES SECTION ===== */
    .features {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 30px;
        margin: 60px 0;
        width: 100%;
    }

    .feature-card {
        background: rgba(255, 255, 255, 0.05);
        backdrop-filter: blur(10px);
        border: 1px solid rgba(255, 255, 255, 0.1);
        border-radius: 20px;
        padding: 30px;
        text-align: center;
        transition: all 0.3s ease;
        position: relative;
        overflow: hidden;
    }

    .feature-card::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        height: 2px;
        background: linear-gradient(90deg, #6366f1, #8b5cf6, #ec4899);
        transform: scaleX(0);
        transition: transform 0.3s ease;
    }

    .feature-card:hover {
        transform: translateY(-10px);
        background: rgba(255, 255, 255, 0.08);
        box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
    }

    .feature-card:hover::before {
        transform: scaleX(1);
    }

    .feature-icon {
        font-size: 3rem;
        margin-bottom: 20px;
        display: block;
    }

    .feature-card h3 {
        font-size: 1.4rem;
        font-weight: 600;
        margin-bottom: 15px;
        color: #f1f5f9;
    }

    .feature-card p {
        color: #cbd5e1;
        line-height: 1.6;
        font-size: 1rem;
    }

    /* ===== FOOTER STYLES ===== */
    .main-footer {
        margin-top: auto;
        padding: 30px 0;
        text-align: center;
        background: rgba(0, 0, 0, 0.2);
        backdrop-filter: blur(10px);
        border-top: 1px solid rgba(255, 255, 255, 0.1);
    }

    .main-footer p {
        color: #94a3b8;
        font-size: 0.95rem;
        font-weight: 300;
    }

    /* ===== QUIZ STYLES (untuk halaman quiz) ===== */
    #quiz-container {
        max-width: 600px;
        margin: auto;
        padding: 40px;
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        border-radius: 25px;
        box-shadow: 0 25px 50px rgba(0, 0, 0, 0.15);
        color: #1e293b;
        border: 1px solid rgba(255, 255, 255, 0.2);
    }

    #question-box {
        font-size: 1.4rem;
        margin-bottom: 30px;
        font-weight: 500;
        line-height: 1.5;
    }

    #answers-box button {
        display: block;
        width: 100%;
        margin: 15px 0;
        padding: 15px 20px;
        font-size: 1.1rem;
        border: 2px solid #e2e8f0;
        border-radius: 15px;
        background-color: #f8fafc;
        cursor: pointer;
        transition: all 0.3s ease;
        font-weight: 500;
        text-align: left;
    }

    #answers-box button:hover {
        background-color: #f1f5f9;
        border-color: #6366f1;
        transform: translateX(5px);
    }

    #answers-box button.correct {
        background-color: #10b981;
        color: white;
        border-color: #059669;
    }

    #answers-box button.wrong {
        background-color: #ef4444;
        color: white;
        border-color: #dc2626;
    }

    #next-btn {
        margin-top: 30px;
        padding: 15px 30px;
        font-size: 1.1rem;
        background: linear-gradient(135deg, #6366f1, #8b5cf6);
        color: white;
        border: none;
        border-radius: 15px;
        cursor: pointer;
        font-weight: 600;
        transition: all 0.3s ease;
    }

    #next-btn:hover {
        transform: translateY(-2px);
        box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
    }

    #score-box {
        font-size: 1.6rem;
        margin-top: 40px;
        font-weight: 600;
    }

    /* ===== ANIMATION CLASSES ===== */
    .fade-in-up {
        animation: fadeInUp 0.8s ease-out;
    }

    .pulse {
        animation: pulse 2s infinite;
    }

    /* ===== RESPONSIVE DESIGN ===== */
    @media (max-width: 768px) {
        .main-header h1 {
            font-size: 2.2rem;
        }

        .main-header p {
            font-size: 1.1rem;
        }

        .btn-mulai {
            padding: 18px 40px;
            font-size: 1.2rem;
            min-width: 250px;
        }

        .navigation-section {
            grid-template-columns: 1fr;
            gap: 20px;
        }

        .features {
            grid-template-columns: 1fr;
            gap: 20px;
        }

        .feature-card {
            padding: 25px;
        }

        .section-header {
            flex-direction: column;
            align-items: flex-start;
        }

        .section-header h2 {
            font-size: 1.8rem;
        }

        .material-item {
            flex-direction: column;
            text-align: center;
            gap: 15px;
        }

        .modal-content {
            width: 95%;
            margin: 20px;
        }

        .modal-header {
            padding: 20px 20px 15px;
        }

        .modal-body {
            padding: 20px;
        }

        .modal-footer {
            padding: 15px 20px 20px;
            flex-direction: column;
        }

        #quiz-container {
            padding: 30px 20px;
            margin: 20px;
        }
    }

    @media (max-width: 480px) {
        .container {
            padding: 0 15px;
        }

        .main-header h1 {
            font-size: 1.8rem;
        }

        .brand-name {
            font-size: 2rem;
        }

        .btn-mulai {
            padding: 15px 30px;
            font-size: 1.1rem;
            min-width: 220px;
        }

        .nav-card {
            padding: 30px 20px;
        }

        .material-category {
            padding: 20px;
        }

        .material-category h3 {
            font-size: 1.5rem;
        }

        .btn-tambah-materi {
            display: inline-block;
            padding: 12px 24px;
            background-color: #4CAF50;
            /* hijau lembut */
            color: white;
            font-size: 16px;
            font-weight: 600;
            text-decoration: none;
            border-radius: 8px;
            box-shadow: 0 4px 14px rgba(0, 0, 0, 0.1);
            transition: transform 0.2s ease, box-shadow 0.2s ease;
            animation: pulse 2s infinite;
        }

        .btn-tambah-materi:hover {
            transform: scale(1.05);
            box-shadow: 0 6px 18px rgba(0, 0, 0, 0.2);
        }

        @keyframes pulse {
            0% {
                transform: scale(1);
                box-shadow: 0 0 0 0 rgba(76, 175, 80, 0.7);
            }

            70% {
                transform: scale(1.03);
                box-shadow: 0 0 0 10px rgba(76, 175, 80, 0);
            }

            100% {
                transform: scale(1);
                box-shadow: 0 0 0 0 rgba(76, 175, 80, 0);
            }
        }
    }
}