/* Global Styles */
body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-color: #f5f5f5;
}

.app {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
}

.app-header {
    text-align: center;
    margin-bottom: 30px;
}

.app-header h1 {
    color: #333;
    margin: 0 0 10px;
}

.app-header p {
    color: #666;
    margin: 0;
}

.error {
    background: #ffebee;
    color: #c62828;
    padding: 10px;
    border-radius: 4px;
    margin-bottom: 20px;
    border-left: 4px solid #f44336;
}

/* Settings Styles */
.settings {
    background: #f9f9f9;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.settings h2 {
    text-align: center;
    color: #333;
    margin-bottom: 30px;
}

.setting-group {
    margin-bottom: 20px;
}

.setting-group h3 {
    color: #444;
    margin-bottom: 10px;
}

.setting-group label {
    display: block;
    margin-bottom: 10px;
    color: #555;
    font-weight: 500;
}

.setting-group input[type="number"] {
    margin-left: 10px;
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    width: 60px;
}

.checkbox-label {
    display: flex;
    align-items: center;
    margin-bottom: 8px;
    font-weight: normal;
    color: #555;
}

.checkbox-label input[type="checkbox"] {
    margin-right: 8px;
    width: 18px;
    height: 18px;
}

.start-button {
    display: block;
    width: 100%;
    padding: 12px;
    background: #4CAF50;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    margin-top: 20px;
    text-decoration: none;
    text-align: center;
}

.start-button:hover {
    background: #45a049;
}

/* Quiz Styles */
.quiz {
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    text-align: center;
}

.quiz-header {
    margin-bottom: 30px;
}

.progress-text {
    color: #666;
    font-size: 14px;
}

.problem-form {
    margin: 40px 0;
}

.problem {
    font-size: 48px;
    font-weight: bold;
    color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}

.number {
    font-size: 48px;
}

.operation {
    font-size: 36px;
    color: #666;
}

.equals {
    font-size: 36px;
    color: #333;
}

.answer-input input {
    font-size: 48px;
    width: 80px;
    text-align: center;
    border: 2px solid #ddd;
    border-radius: 8px;
    padding: 10px;
    background: #f9f9f9;
    font-weight: bold;
    color: #333;
}

.answer-input input:focus {
    outline: none;
    border-color: #4CAF50;
    background: white;
}

.submit-button {
    padding: 12px 24px;
    background: #2196F3;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    margin: 20px 0;
}

.submit-button:hover {
    background: #1976D2;
}

.instructions {
    color: #888;
    font-size: 14px;
    margin-top: 20px;
}

/* Results Styles */
.results {
    background: #f9f9f9;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    text-align: center;
}

.results h2 {
    color: #333;
    margin-bottom: 30px;
}

.stats {
    display: grid;
    gap: 15px;
    margin-bottom: 30px;
}

.stat {
    background: white;
    padding: 15px;
    border-radius: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.stat-label {
    color: #666;
    font-size: 14px;
}

.stat-value {
    color: #333;
    font-size: 18px;
    font-weight: bold;
}

.feedback {
    margin: 20px 0;
    padding: 15px;
    background: #e3f2fd;
    border-radius: 8px;
    border-left: 4px solid #2196F3;
}

.feedback p {
    margin: 0;
    color: #1976D2;
    font-size: 16px;
}

.restart-button {
    display: inline-block;
    padding: 12px 24px;
    background: #FF9800;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    text-decoration: none;
}

.restart-button:hover {
    background: #F57C00;
}

/* Responsive */
@media (max-width: 600px) {
    .app {
        padding: 10px;
    }

    .problem {
        font-size: 36px;
    }

    .number {
        font-size: 36px;
    }

    .answer-input input {
        font-size: 36px;
        width: 60px;
    }
}