/* :root 定義全域 CSS 變數 */
:root {
    --primary-color: #00529B;
    --primary-color-light: #e7f5ff;
    --secondary-color: #007bff;
    --secondary-color-hover: #0056b3;
    --danger-color: #dc3545;
    --danger-color-hover: #c82333;
    --warning-color: #FFC107;
    --warning-color-hover: #FFD54F;

    --text-color-main: #333;
    --text-color-subtle: #666;
    --border-color: #e0e0e0;
    --background-soft: #f4f7f9;
    --background-white: #fff;
    --border-radius-main: 8px;
}

/* 基本樣式 */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--background-soft); /* 使用一個柔和的灰白色背景，增加質感 */
    color: var(--text-color-main); /* 主要文字顏色 */
    line-height: 1.6;
    margin: 0;
}

header {
    text-align: center;
    padding: 15px 10px;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 1%;
}

h1 {
    color: var(--primary-color);
    font-size: 2.2rem;
    margin: 0 0 10px 0;
}

header p {
    color: var(--text-color-subtle);
    font-size: 1rem;
}

/* 控制項樣式 */
.controls {
    display: flex;
    justify-content: center;
    gap: 20px;
    align-items: center;
    margin-bottom: 2.5rem; /* 使用 rem 保持一致性 */
    background-color: var(--background-white);
    padding: 10px;
    border-radius: var(--border-radius-main);
    max-width: 860px;
    margin-left: auto;
    margin-right: auto;
}

.select-group label {
    margin-right: 8px;
    font-weight: bold;
    color: #555;
}

.select-group select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    padding: 8px 12px;
    border: 1px solid #ddd; /* 或者 var(--border-color) */
    border-radius: var(--border-radius-main);
    font-size: 16px;
    background-color: #f9f9f9;
    background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23007CB2%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E');
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 10px;
    padding-right: 30px;
    cursor: pointer;
}

/* 單字卡片容器 */
#word-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    max-width: 900px;
    margin: 40px auto;
    padding: 20px;
}

#word-list .message {
    grid-column: 1 / -1;
    text-align: center;
}

/* 單字卡片樣式 */
.word-card {
    background-color: var(--background-white);
    border-radius: var(--border-radius-main);
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
    padding: 20px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 200px;
    transition: transform 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
}

.word-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.08);
}

.word-info {
    text-align: center;
    width: 100%;
}

.word-card .english {
    font-size: 2.5rem;
    font-weight: bold;
    color: var(--primary-color);
    margin: 0 0 5px 0;
}

.word-card .phonetic {
    font-size: 1.1rem;
    color: var(--text-color-subtle);
    margin: 0 0 10px 0;
}

.word-card .details {
    font-size: 1.3rem;
    color: #34495e;
    margin: 0;
}

.word-card .pos {
    display: inline-block;
    background-color: var(--primary-color-light);
    color: var(--primary-color);
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.9rem;
    font-style: italic;
    margin-right: 8px;
}

.word-card .sentence {
    font-size: 1rem;
    color: #777;
    margin: 10px 0 0 0;
    font-style: italic;
}

/* 播放按鈕 */
.play-audio-btn {
    background-color: var(--warning-color);
    color: white;
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 24px;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    align-self: center;
    transition: background-color 0.2s;
}

.play-audio-btn:hover {
    background-color: var(--warning-color-hover);
}

.play-audio-btn:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

/* --- 教學模式控制按鈕樣式 --- */
#toggle-teaching-mode {
    padding: 8px 16px;
    border: 1px solid #ddd;
    border-radius: var(--border-radius-main);
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    background-color: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

#toggle-teaching-mode:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    background-color: var(--secondary-color-hover);
    border-color: var(--secondary-color-hover);
    color: white;
}

/* 當 Modal 彈出時，「結束教學」按鈕的樣式 */
.modal-open #toggle-teaching-mode {
    background-color: var(--danger-color); /* 紅色 */
    border-color: var(--danger-color);
}
.modal-open #toggle-teaching-mode:hover {
    background-color: var(--danger-color-hover);
    border-color: var(--danger-color-hover);
}

/* --- Modal (教學模式彈出視窗) 樣式 --- */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh; /* 使用 vh 單位確保佔滿整個視窗高度 */
    background-color: var(--background-white); /* 根據要求改為純白背景 */
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Modal 內的單字卡列表容器 */
.modal-content #word-list {
    min-height: initial;
    grid-template-columns: 1fr; /* 在 Modal 中永遠是單欄 */
}

/* Modal 內的單字卡 */
.modal-content .word-card {
    display: none;
    max-width: 600px;
    width: 90%; /* 在小螢幕上佔 90% 寬度 */
    transform: translateY(0);
    border: none; /* 根據要求移除框線 */
    box-shadow: none; /* 同時移除陰影，讓其完全融入背景 */
}

.modal-content .word-card:hover {
    transform: none;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.modal-content .word-card.active {
    display: flex;
}

.modal-content .word-card .english {
    font-size: 18rem; /* 根據要求放大 3 倍 (6rem * 3) */
    line-height: 1.2;
    white-space: nowrap; /* 新增：防止文字自動換行，以便 JS 測量寬度 */
}

/* Modal 的關閉按鈕 */
.modal-close-btn {
    position: absolute;
    top: 20px;
    right: 30px;
    font-size: 40px;
    color: var(--text-color-main); /* 因應白色背景，將關閉按鈕改為深色 */
    background: none;
    border: none;
    cursor: pointer;
    transition: transform 0.2s;
}

.modal-close-btn:hover {
    transform: scale(1.2);
}