:root {
    --font-scale: 1;
    --primary: #0984e3;
    --success: #00b894;
    --danger: #d63031;
    --text-main: #2d3436;
    --text-kana: #051024;
    --text-muted: #636e72;
    --text-light: #b2bec3;
    --bg-color: #f0f4f8;
    --card-bg: #ffffff;
    --border-color: #dfe6e9;
}

* {
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    justify-content: center;
    height: 100dvh; /* ✨ 關鍵修正：改用動態視窗高度 */
    min-height: -webkit-fill-available; /* 支援 iOS Safari 的防呆寫法 */
    overflow: hidden; 
}

html {
    height: -webkit-fill-available; /* 配合上方設定 */
    font-size: calc(16px * var(--font-scale));
}

.app-container {
    width: 100%;
    max-width: 600px;
    display: flex;
    flex-direction: column;
    padding: 10px;
    /* ✨ 新增安全邊距，防止被首頁條(Home Indicator)擋住 */
    padding-bottom: calc(10px + env(safe-area-inset-bottom)); 
    height: 100%;
}

/* 頂部控制列 */
.top-bar { display: none; }
.hud { display: flex; justify-content: space-between; align-items: center; padding: 5px 15px; background: var(--card-bg); border-radius: 15px; box-shadow: 0 2px 10px rgba(0,0,0,0.05); font-weight: bold; margin-bottom: 12px; flex-shrink: 0;}

/* 元件與按鈕 */
.icon-btn { background: none; border: none; font-size: 1.2rem; cursor: pointer; padding: 5px 10px; border-radius: 8px; transition: 0.2s; -webkit-tap-highlight-color: transparent;}
.icon-btn:hover { background: #dfe6e9; }
.action-btn { background: var(--primary); color: white; border: none; padding: 12px 20px; border-radius: 12px; font-size: 1.1rem; cursor: pointer; font-weight: bold; transition: 0.2s; -webkit-tap-highlight-color: transparent;}
.action-btn:active { transform: scale(0.96); }
.full-width { width: 100%; margin-top: 15px; }

/* 首頁選單 */
.menu-container { display: flex; flex-direction: column; align-items: center; text-align: center; flex: 1; justify-content: center; overflow-y: auto; }
.menu-container h1 { margin-bottom: 20px; font-size: 2rem; }
#theme-select, #home-tag-select { 
    width: 100%; max-width: 350px; padding: 12px; border-radius: 10px; 
    border: 2px solid var(--border-color); font-size: 1rem; margin-bottom: 10px; 
}

/* 首頁按鈕群組 */
.main-menu-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
    width: 100%;
    max-width: 320px;
    margin-top: 30px;
}

.main-menu-actions .action-btn {
    width: 100%;
    position: relative;
}

.checkbox-group { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; max-width: 400px; margin-top: 10px; }
.checkbox-group label { background: var(--card-bg); padding: 8px 15px; border-radius: 20px; border: 1px solid var(--border-color); cursor: pointer; }

/* --- 單字卡專屬樣式 --- */
.flashcard-wrapper {
    flex: 1; 
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    overflow: hidden; 
    padding-bottom: 10px;
    min-height: 0; /* ✨ 關鍵修正：讓 Flexbox 允許內部卡片縮小，不再把導覽列擠出畫面 */
}
.flashcard {
    background-color: var(--card-bg); width: 100%; height: 100%; border-radius: 1.5rem; box-shadow: 0 10px 25px rgba(0,0,0,0.08); border: 2px solid var(--border-color); display: flex; flex-direction: column; overflow: hidden;
}
.card-content {
    flex: 1; overflow-y: auto; display: flex; flex-direction: column; cursor: pointer; -webkit-tap-highlight-color: transparent;
}
.card-front {
    display: flex; flex-direction: column; justify-content: center; align-items: center; flex: 1; padding: 2rem; text-align: center;
}
.front-jp { font-size: 4.5rem; color: var(--text-main); font-weight: bold; }
.card-back {
    display: none; flex-direction: column; padding: 2rem 1.5rem; flex: 1; cursor: default;
}

.clickable-area { cursor: pointer; border-radius: 1rem; transition: background-color 0.2s; -webkit-tap-highlight-color: transparent; }
.clickable-area:active { background-color: #f5f6fa; }

.back-vocab-section { display: flex; flex-direction: column; align-items: center; text-align: center; gap: 0.3rem; padding: 1rem 0; }
.word-header-container { display: grid; grid-template-columns: 1fr auto 1fr; width: 100%; align-items: center; margin-bottom: 0.5rem; }
.back-jp-main { grid-column: 2; font-size: 3.5rem; font-weight: bold; color: var(--text-main); line-height: 1.1; }
.badge-wrapper { grid-column: 3; justify-self: start; padding-left: 0.8rem; }
.pos-badge { font-size: 1rem; color: #ffffff; font-weight: bold; padding: 0.4rem 0.8rem; border-radius: 0.8rem; white-space: nowrap; }

/* 針對讀音的設定 */
.kana-text { font-size: 1.8rem; color: var(--text-kana); font-weight: bold; display: flex; align-items: center; justify-content: center; flex-wrap: wrap; }
.romaji-text { font-family: monospace; color: var(--text-light); font-size: 1.1rem; }
.zh-text { font-size: 1.6rem; color: var(--text-main); font-weight: bold; margin-top: 0.5rem; }

hr { border: 0; border-top: 2px solid var(--border-color); margin: 1.5rem 0; }

.example-section { display: flex; flex-direction: column; align-items: flex-start; text-align: left; gap: 0.3rem; padding: 1rem 0.5rem; }
.ex-jp-text { font-size: 1.3rem; font-weight: bold; color: var(--text-main); line-height: 1.4; margin-bottom: 0.3rem; }
.ex-kana-text { font-size: 1.05rem; color: var(--text-kana); font-weight: bold; }
.ex-romaji-text { font-family: monospace; font-size: 0.9rem; color: var(--text-light); }
.ex-zh-text { font-size: 1.1rem; color: var(--text-muted); margin-top: 0.3rem; }
.note-text { font-size: 0.95rem; color: #636e72; background: #f5f6fa; padding: 10px; border-radius: 8px; margin-top: 10px; text-align: left; border-left: 4px solid var(--primary); }

.nav-buttons { display: flex; justify-content: space-between; align-items: center; width: 100%; padding: 10px 0; flex-shrink: 0; }
.nav-btn { background-color: #ffffff; border: 2px solid var(--border-color); font-size: 1.8rem; cursor: pointer; padding: 0.6rem 2.5rem; color: var(--primary); transition: 0.2s; border-radius: 1rem; box-shadow: 0 4px 0 var(--border-color); display: flex; align-items: center; justify-content: center; -webkit-tap-highlight-color: transparent; }
.nav-btn:active:not(:disabled) { transform: translateY(4px); box-shadow: 0 0 0 var(--primary); }
.nav-btn:disabled { color: #dcdde1; border-color: #f5f6fa; box-shadow: 0 4px 0 #f5f6fa; cursor: not-allowed; }
.nav-center-controls { display: flex; flex-direction: column; align-items: center; gap: 5px; }
.flip-back-btn { background: none; border: none; color: var(--primary); font-size: 1.2rem; cursor: pointer; font-weight: bold; display: none; }
.flip-back-btn:hover { text-decoration: underline; }

.battle-area { flex: 1; display: flex; flex-direction: column; overflow-y: auto; padding-bottom: 20px;}
.question-card { background: var(--card-bg); padding: 30px 20px; border-radius: 20px; box-shadow: 0 8px 16px rgba(0,0,0,0.05); text-align: center; margin-bottom: 20px; flex-shrink: 0;}
.controls { display: flex; flex-direction: column; gap: 12px; }

.audio-option-row { display: flex; gap: 10px; align-items: center; width: 100%; }
.play-audio-btn { flex: 0 0 60px; height: 60px; border-radius: 15px; background: #74b9ff; color: white; border: none; font-size: 1.5rem; cursor: pointer; box-shadow: 0 4px 0 #0984e3; }
.play-audio-btn:active { transform: translateY(4px); box-shadow: none; }
.select-ans-btn { flex: 1; background: var(--card-bg); color: var(--text-main); border: 2px solid var(--border-color); padding: 15px; border-radius: 15px; font-size: 1.1rem; cursor: pointer; font-weight: bold; }
.select-ans-btn:active { background: #f5f6fa; }

.mic-btn { background: #ff7675; color: white; border: none; padding: 15px 30px; border-radius: 30px; font-size: 1.2rem; cursor: pointer; font-weight: bold; box-shadow: 0 5px 15px rgba(255, 118, 117, 0.4); margin-top: 20px; transition: 0.2s; display: inline-block;}
.mic-btn:active { transform: scale(0.95); background: #d63031; }

.text-left { text-align: left; }
.text-center { text-align: center; }
.success-text { color: var(--success); font-weight: bold; margin: 0 0 5px 0; }
.danger-text { color: var(--danger); font-weight: bold; margin: 0; }
.feedback-box { background: #ffeaa7; padding: 12px; border-radius: 10px; margin-bottom: 15px; }

.modal { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.5); display: flex; justify-content: center; align-items: center; z-index: 100; }
.modal-content { background: var(--card-bg); padding: 30px; border-radius: 20px; width: 90%; max-width: 400px; text-align: center; }

.bottom-controls { width: 100%; display: flex; align-items: center; justify-content: center; gap: 1rem; margin-top: auto; background: var(--card-bg); padding: 0.2rem 1.5rem; border-radius: 1rem; box-shadow: 0 -2px 10px rgba(0,0,0,0.03); border: 2px solid var(--border-color); flex-shrink: 0; }
#font-scale-slider { flex: 1; cursor: pointer; }

/* --- 辭典風重音標示法 --- */
.mora {
    display: inline-block;
    position: relative;
    padding: 0 1px; /* 微調間距讓紅線相連 */
    margin-top: 8px; /* 預留上方畫線的空間 */
    border-top: 3px solid transparent; 
    line-height: 1.2;
}

/* 高音拍：上方畫紅線 */
.pitch-high {
    border-top: 3px solid #e74c3c;
}

/* 音調下降點：在右側畫一條垂直短線 */
.pitch-drop::after {
    content: '';
    position: absolute;
    top: -3px; 
    right: -2px; 
    width: 3px;
    height: 50%; 
    background-color: #e74c3c;
}

/* ✨ 新增：超扁平螢幕/手機電腦版模式防護 */
@media (max-height: 650px) {
    .card-front, .card-back {
        padding: 1rem; /* 縮小卡片內距 */
    }
    .front-jp {
        font-size: 3rem; /* 縮小大字體 */
    }
    .back-jp-main {
        font-size: 2.5rem;
    }
    .question-card {
        padding: 15px 10px; /* 測驗卡片也縮小 */
        margin-bottom: 10px;
    }
    .bottom-controls {
        padding: 0.5rem 1rem; /* 縮小底部控制器 */
    }
}

/* 將原本的頂部控制列隱藏 */
.top-bar { display: none; }

/* 元件與按鈕基底更淺的顏色設定已直接套用於 inline-style 中，這邊調整細節 */
#theme-select, #home-tag-select { 
    width: 100%; max-width: 350px; padding: 12px; border-radius: 10px; 
    border: 2px solid var(--border-color); font-size: 1rem; margin-bottom: 10px; 
}

/* 首頁按鈕群組 */
.main-menu-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
    width: 100%;
    max-width: 320px;
    margin-top: 30px;
}

.main-menu-actions .action-btn {
    width: 100%;
    position: relative;
    color: var(--text-main); /* 因為底色變淺，文字改回深色以利閱讀 */
}

/* 特別調整主按鈕字體顏色，如果覺得不夠明顯可以改回 white */
#view-cards-btn, #start-btn, #daily-btn {
    color: #2d3436; 
}

/* 隱藏原生頂部工具列 */
.top-bar { display: none; }

#theme-select, #home-tag-select { 
    width: 100%; max-width: 350px; padding: 12px; border-radius: 10px; 
    border: 2px solid var(--border-color); font-size: 1rem; margin-bottom: 10px; 
}

/* 首頁按鈕群組 */
.main-menu-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
    width: 100%;
    max-width: 320px;
    margin-top: 30px;
}

.main-menu-actions .action-btn {
    width: 100%;
}

/* === 新增：無背景按鈕 === */
.ghost-btn {
    background: transparent;
    border: none;
    box-shadow: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 1rem;
    font-weight: bold;
    transition: 0.2s;
    padding: 5px 10px;
    border-radius: 8px;
}
.ghost-btn:hover {
    background: rgba(0,0,0,0.05);
}

/* --- 按鈕疊加效果設定 --- */

/* 外層容器：作為絕對定位的基準點 */
.action-btn-wrapper {
    position: relative;
    width: 100%;
    display: flex; 
}

/* 疊加在右側的按鈕 (測驗設定齒輪) */
.overlay-icon-btn {
    position: absolute;
    right: 8px; /* 固定在距離右邊 8px 的位置 */
    top: 50%;
    transform: translateY(-50%); /* 垂直置中 */
    background: rgba(255, 255, 255, 0.0); /* 半透明底色，讓它看起來是個小按鈕 */
    border: none;
    border-radius: 8px;
    padding: 6px 10px;
    font-size: 1.2rem;
    cursor: pointer;
    z-index: 10;
    transition: 0.2s;
    -webkit-tap-highlight-color: transparent;
}
/*.overlay-icon-btn:hover {
    background: rgba(255, 255, 255, 0.8);
}*/

/* 疊加在右側的純文字標籤 (每日挑戰狀態 ❌/✅) */
.overlay-icon-text {
    position: absolute;
    right: 15px; /* 固定在距離右邊 15px 的位置 */
    top: 50%;
    transform: translateY(-50%); /* 垂直置中 */
    font-size: 1.3rem;
    pointer-events: none; /* ❗穿透點擊：確保點擊符號時，還是算點到下面的「每日挑戰」按鈕 */
    z-index: 10;
}