* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    max-width: 600px;
    width: 100%;
}

h1 {
    text-align: center;
    color: #667eea;
    margin-bottom: 30px;
    font-size: 2.5em;
}

h2 {
    text-align: center;
    color: #333;
    margin-bottom: 20px;
}

.menu {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.btn {
    padding: 15px 30px;
    font-size: 1.2em;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: bold;
    color: white;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.btn-easy {
    background: linear-gradient(135deg, #84fab0 0%, #8fd3f4 100%);
}

.btn-medium {
    background: linear-gradient(135deg, #ffd89b 0%, #19547b 100%);
}

.btn-hard {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.btn-submit {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.btn-back, .btn-restart {
    background: linear-gradient(135deg, #868f96 0%, #596164 100%);
    margin-top: 20px;
}

.hidden {
    display: none !important;
}

.stats {
    display: flex;
    justify-content: space-around;
    margin-bottom: 30px;
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
}

.stat-item {
    text-align: center;
}

.label {
    display: block;
    color: #666;
    font-size: 0.9em;
    margin-bottom: 5px;
}

.value {
    display: block;
    color: #667eea;
    font-size: 1.8em;
    font-weight: bold;
}

.question-box {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 40px;
    border-radius: 15px;
    margin-bottom: 30px;
}

.question-box h2 {
    color: white;
    font-size: 2.5em;
    margin: 0;
}

.answer-section {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

#answer {
    flex: 1;
    padding: 15px;
    font-size: 1.2em;
    border: 2px solid #ddd;
    border-radius: 10px;
    text-align: center;
}

#answer:focus {
    outline: none;
    border-color: #667eea;
}

.feedback {
    text-align: center;
    font-size: 1.2em;
    font-weight: bold;
    min-height: 30px;
    margin-bottom: 10px;
}

.feedback.correct {
    color: #28a745;
}

.feedback.wrong {
    color: #dc3545;
}

.game-over {
    text-align: center;
}

.final-score {
    font-size: 2em;
    color: #667eea;
    margin: 20px 0;
}

.final-score span {
    font-weight: bold;
    font-size: 1.5em;
}

.message {
    font-size: 1.2em;
    color: #666;
    margin-bottom: 30px;
}