* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 30px 40px;
    max-width: 600px;
    width: 100%;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    min-height: 400px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.screen {
    display: none;
    flex-direction: column;
    gap: 20px;
}

.screen.active {
    display: flex;
}

h1 {
    font-size: 2.5rem;
    text-align: center;
    color: #333;
}

h2 {
    font-size: 1.5rem;
    color: #444;
}

button {
    background: #667eea;
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 30px;
    font-size: 1.1rem;
    cursor: pointer;
    transition: 0.3s;
    align-self: center;
}

button:hover {
    background: #764ba2;
    transform: scale(1.05);
}

button:disabled {
    opacity: 0.5;
    pointer-events: none;
}

.progress {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 10px;
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: #e0e0e0;
    border-radius: 10px;
    overflow: hidden;
}

#progress-fill {
    height: 100%;
    background: #667eea;
    transition: width 0.3s;
}

#answers-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.answer-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 18px;
    border: 2px solid #ddd;
    border-radius: 12px;
    cursor: pointer;
    transition: 0.2s;
    background: #f9f9f9;
}

.answer-option:hover {
    border-color: #667eea;
    background: #f0f2ff;
}

.answer-option input[type="radio"] {
    width: 18px;
    height: 18px;
    accent-color: #667eea;
    cursor: pointer;
}

.answer-option label {
    flex: 1;
    cursor: pointer;
    font-size: 1rem;
}

.answer-option.correct {
    border-color: #28a745;
    background: #d4edda;
}

.answer-option.wrong {
    border-color: #dc3545;
    background: #f8d7da;
}

.answer-option.disabled {
    pointer-events: none;
    opacity: 0.8;
}

.feedback {
    text-align: center;
    font-size: 1.1rem;
    font-weight: bold;
    min-height: 30px;
}

#next-btn {
    display: none;
    background: #28a745;
}

#result-screen p {
    font-size: 1.2rem;
    text-align: center;
}

#result-screen span {
    font-weight: bold;
    color: #667eea;
}

@media (max-width: 500px) {
    .container {
        padding: 20px;
    }
    h1 {
        font-size: 2rem;
    }
}