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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 40px;
    padding: 20px 0;
    border-bottom: 2px solid #e0e0e0;
}

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 8px;
    color: #232f3e;
}

.subtitle {
    font-size: 1rem;
    color: #666;
    font-weight: 300;
}

/* Main Content */
.main-content {
    background-color: white;
    border-radius: 8px;
    padding: 30px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* Question Counter */
.question-counter {
    text-align: center;
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid #e0e0e0;
}

/* Question Container */
.question-container {
    margin-bottom: 30px;
}

.question-text {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 25px;
    padding: 15px;
    background-color: #fafafa;
    border-left: 4px solid #232f3e;
    border-radius: 4px;
}

/* Options Container */
.options-container {
    margin-bottom: 25px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.option {
    display: flex;
    align-items: flex-start;
    padding: 12px;
    border: 1px solid #e0e0e0;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.option:hover {
    background-color: #f9f9f9;
    border-color: #232f3e;
}

.option input[type="radio"] {
    margin-right: 12px;
    margin-top: 2px;
    cursor: pointer;
    accent-color: #232f3e;
}

.option label {
    display: flex;
    align-items: flex-start;
    cursor: pointer;
    flex: 1;
}

.option-letter {
    font-weight: 600;
    min-width: 25px;
    color: #232f3e;
}

.option-text {
    margin-left: 8px;
    flex: 1;
}

/* Correct Answer Highlighting */
.option.correct {
    background-color: #e8f5e9;
    border-color: #4caf50;
}

.option.correct .option-letter {
    color: #4caf50;
}

/* Button Container */
.button-container {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    font-size: 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
}

.btn-primary {
    background-color: #232f3e;
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background-color: #1a2332;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

.btn-primary:disabled {
    background-color: #ccc;
    cursor: not-allowed;
    opacity: 0.6;
}

.btn-secondary {
    background-color: #f0f0f0;
    color: #333;
    border: 1px solid #ddd;
}

.btn-secondary:hover:not(:disabled) {
    background-color: #e0e0e0;
    border-color: #999;
}

.btn-secondary:disabled {
    background-color: #f5f5f5;
    color: #999;
    cursor: not-allowed;
    border-color: #ddd;
}

/* Answer Display */
.answer-display {
    padding: 15px;
    background-color: #e8f5e9;
    border-left: 4px solid #4caf50;
    border-radius: 4px;
    margin-bottom: 20px;
    color: #2e7d32;
    font-weight: 500;
}

.answer-display.hidden {
    display: none;
}

/* Navigation */
.navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 15px;
    padding-top: 20px;
    border-top: 1px solid #e0e0e0;
}

.navigation .btn {
    flex: 1;
    padding: 12px 20px;
}

/* Jump to Question */
.jump-to-question {
    display: flex;
    gap: 8px;
    align-items: center;
}

#jump-input {
    padding: 10px 12px;
    font-size: 0.95rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    width: 140px;
    transition: border-color 0.2s ease;
}

#jump-input:focus {
    outline: none;
    border-color: #232f3e;
    box-shadow: 0 0 0 2px rgba(35, 47, 62, 0.1);
}

#jump-input::placeholder {
    color: #999;
}

.jump-to-question .btn {
    flex: 0;
    padding: 10px 16px;
    white-space: nowrap;
}

/* Error Message */
.error-message {
    padding: 15px;
    background-color: #ffebee;
    border-left: 4px solid #f44336;
    border-radius: 4px;
    color: #c62828;
    margin-bottom: 20px;
}

.error-message.hidden {
    display: none;
}

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

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

    .main-content {
        padding: 20px;
    }

    .question-text {
        font-size: 1rem;
    }

    .navigation {
        flex-direction: column;
    }

    .navigation .btn {
        width: 100%;
    }

    .jump-to-question {
        width: 100%;
        flex-direction: column;
    }

    #jump-input {
        width: 100%;
    }

    .jump-to-question .btn {
        width: 100%;
    }
}