body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f4f4f4;
    margin: 0;
}

.container {
    background-color: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 90%;
    max-width: 800px;
}

h1 {
    color: #333;
    margin-bottom: 20px;
}

.sheet-selection-container {
    margin-bottom: 20px;
}

#sheet-selector {
    padding: 8px;
    border-radius: 5px;
    border: 1px solid #ccc;
    font-size: 1em;
}

.main-buttons {
    display: block;
    width: max-content;
    margin: 20px auto;
}

.main-buttons button {
    background-color: #007bff;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s ease;
}

.main-buttons button:hover {
    background-color: #0056b3;
}

/* 전체 문장 목록 스타일 */
#sentence-list {
    text-align: left;
    max-height: 400px;
    overflow-y: auto;
    border: 1px solid #ddd;
    border-radius: 5px;
    padding: 15px;
}

.sentence-item {
    padding: 10px;
    border-bottom: 1px solid #eee;
}

.sentence-item:last-child {
    border-bottom: none;
}

.english-text {
    font-weight: bold;
    color: #333;
}

.korean-text {
    color: #555;
    margin-top: 5px;
}

/* 퀴즈 모드 관련 스타일 */
.hidden {
    display: none;
}

#quiz-display {
    min-height: 80px;
    margin-bottom: 20px;
    padding: 15px;
    border: 1px solid #ddd;
    border-radius: 5px;
    background-color: #e9e9e9;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.quiz-text {
    font-size: 1.2em;
    font-weight: bold;
    color: #555;
    min-height: 20px;
}

#sentence-hint {
    font-size: 0.9em;
    color: #777;
    margin-top: 5px;
    display: none; /* 초기에는 숨김 */
}

textarea {
    width: calc(100% - 20px);
    height: 100px;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 1em;
    resize: vertical;
}

.quiz-buttons {
    display: flex;
    justify-content: center;
    align-items: center;
}

.quiz-buttons button, #back-to-list-button {
    background-color: #007bff;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1em;
    margin: 5px;
    transition: background-color 0.3s ease;
}

.quiz-buttons button:hover, #back-to-list-button:hover {
    background-color: #0056b3;
}

#feedback {
    margin-top: 15px;
    font-weight: bold;
    min-height: 20px;
}

#feedback.correct {
    color: green;
}

#feedback.incorrect {
    color: red;
}

.score-display {
    margin-top: 10px;
}

#score, #total-sentences {
    font-weight: bold;
    color: #007bff;
}