/* ==========================================================================
   Component Styles - 组件样式 (v2.0 - 支持主题切换)
   ========================================================================== */

/* --- 组件: 筛选器与控制按钮 --- */
.filter-btn {
    padding: 8px 20px;
    border: 2px solid var(--border-color); /* 使用变量 */
    border-radius: 50px;
    background: var(--bg-secondary-color); /* 使用变量 */
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s ease;
    color: var(--text-sub); /* 使用变量 */
}
/* 激活状态：使用默认主题色 */
.filter-btn.active {
    background: var(--theme-color-default);
    color: var(--text-inverse);
    border-color: var(--theme-color-default);
}
/* 激活状态（已掌握）：使用特定状态色 */
.filter-btn[data-filter="learned"].active {
    background: var(--color-learned);
    border-color: var(--color-learned);
}
/* 悬浮状态 */
.filter-btn:not(.active):hover {
    border-color: var(--border-color-hover);
    color: var(--text-main);
}


/* --- 【新增】主题切换按钮 与 随机按钮 (样式统一) --- */
.shuffle-btn,
.theme-toggle-btn {
    width: 38px;
    height: 38px;
    padding: 0;
    border: 2px solid var(--border-color); /* 使用变量 */
    border-radius: 50%;
    background: var(--bg-secondary-color); /* 使用变量 */
    cursor: pointer;
    color: var(--text-sub); /* 使用变量 */
    display: flex;
    align-items: center;
    justify-content: center;
    margin-left: 10px;
    transition: all 0.2s ease;
}
.shuffle-btn:hover,
.theme-toggle-btn:hover {
    border-color: var(--border-color-hover);
    color: var(--text-main);
}
.shuffle-btn svg,
.theme-toggle-btn svg {
    width: 20px;
    height: 20px;
    transition: transform 0.3s ease;
}
.shuffle-btn:active svg {
    transform: rotate(45deg);
}

/* 主题图标切换逻辑 */
.theme-toggle-btn .icon-moon { display: none; } /* 默认隐藏月亮 */
body.dark-mode .theme-toggle-btn .icon-sun { display: none; } /* 深色模式下隐藏太阳 */
body.dark-mode .theme-toggle-btn .icon-moon { display: block; } /* 深色模式下显示月亮 */


/* --- 组件: 加载/空状态提示 --- */
.loading-state { grid-column: 1 / -1; text-align: center; font-size: 1.2rem; color: var(--text-sub); padding: 4rem 0; }


/* --- 组件: 3D 翻转卡片 (核心与通用) --- */
.card {
    background-color: transparent;
    height: 400px;
    perspective: 1000px;
    cursor: pointer;
    transition: opacity 0.3s ease-in-out, transform 0.3s ease-in-out;
    animation: card-fade-in 0.5s ease-out forwards;
}
@keyframes card-fade-in {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}
.card-inner { position: relative; width: 100%; height: 100%; transition: transform 0.6s cubic-bezier(0.4, 0.2, 0.2, 1), background-color 0.3s ease, box-shadow 0.3s ease; transform-style: preserve-3d; box-shadow: var(--shadow); border-radius: var(--radius-lg); }
.card.is-flipped .card-inner { transform: rotateY(180deg); }
.card-front, .card-back { position: absolute; width: 100%; height: 100%; backface-visibility: hidden; border-radius: var(--radius-lg); background: var(--card-bg); border: 2px solid transparent; display: flex; flex-direction: column; overflow: hidden; }


/* --- 组件: 单词卡片正面 --- */
.card-front {
    justify-content: space-between;
    padding: 2rem 1.5rem;
    border-color: color-mix(in srgb, var(--theme-color) 40%, transparent);
}
.prefix-badge {
    position: absolute;
    top: 1rem;
    left: 1rem;
    font-size: 0.8rem;
    font-weight: bold;
    padding: 2px 8px;
    border-radius: 4px;
    text-transform: uppercase;
    opacity: 0.8;
    color: var(--theme-color);
    background: color-mix(in srgb, var(--theme-color) 10%, transparent);
}
.visual-area { flex-grow: 1; display: flex; align-items: center; justify-content: center; padding: 1rem; }
.visual-area svg { width: 120px; height: 120px; transition: transform 0.3s ease; }
.card:hover .visual-area svg { transform: scale(1.1); }
.visual-area .layer-root { stroke: var(--text-sub); color: var(--text-sub); opacity: 0.7; stroke-width: 2; }
.visual-area .layer-prefix { stroke: color-mix(in srgb, var(--theme-color) 40%, transparent); color: color-mix(in srgb, var(--theme-color) 40%, transparent); stroke-width: 2.5; transition: opacity 0.3s ease, transform 0.3s ease; }
.card.prefix-hidden .visual-area .layer-prefix { opacity: 0; transform: scale(0.8); }
.word-area { display: flex; align-items: center; justify-content: center; gap: 10px; margin-bottom: 0.5rem; }
.word-text { font-size: 2rem; font-weight: 800; color: var(--theme-color); }
.hint-text { font-size: 0.8rem; color: var(--text-sub); text-align: center; }


/* --- 组件: 单词卡片背面 --- */
.card-back {
    transform: rotateY(180deg);
    padding: 2rem 1.5rem;
    text-align: left;
    background-color: var(--card-back-bg);
    gap: 1.5rem;
}
.breakdown-box {
    font-family: 'Courier New', monospace;
    background: var(--border-color);
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    text-align: center;
    font-weight: bold;
    color: var(--text-code);
    flex-shrink: 0;
}
.meaning-section { flex-shrink: 0; }
.cn-translation { font-size: 1.4rem; color: var(--text-highlight); margin-bottom: 0.5rem; }
.imagery-text { font-size: 0.95rem; color: var(--text-sub); line-height: 1.4; font-style: italic; border-left: 3px solid var(--border-imagery); padding-left: 10px; }
.sentence-section {
    flex-grow: 1;
    overflow-y: auto;
    min-height: 0;
    background: var(--card-back-section-bg);
    padding: 1rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
}
.sentence-block + .sentence-block {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}
.sentence-en { font-weight: 500; margin-bottom: 0.5rem; color: var(--text-main); }
.sentence-cn { font-size: 0.9rem; color: var(--text-sub); margin-bottom: 0.8rem; }


/* --- 组件: 卡片上的按钮 (SVG切换, 标记, 音频) --- */
.toggle-prefix-btn, .mark-btn { position: absolute; width: 32px; height: 32px; background: none; border: none; border-radius: 50%; cursor: pointer; color: var(--text-sub); display: flex; align-items: center; justify-content: center; transition: all 0.2s ease; z-index: 10; }
.toggle-prefix-btn { top: 1rem; right: 1rem; }
.mark-btn { bottom: 1rem; right: 1rem; }
.toggle-prefix-btn:hover, .mark-btn:hover { background-color: rgba(0,0,0,0.05); }
body.dark-mode .toggle-prefix-btn:hover, body.dark-mode .mark-btn:hover { background-color: rgba(255,255,255,0.1); }
.mark-btn:hover { transform: scale(1.1); }
.toggle-prefix-btn svg, .mark-btn svg { width: 20px; height: 20px; }
.mark-btn svg { width: 24px; height: 24px; }
.toggle-prefix-btn .icon-eye-off { display: none; }
.toggle-prefix-btn.is-toggled .icon-eye { display: none; }
.toggle-prefix-btn.is-toggled .icon-eye-off { display: block; }
.mark-btn .icon-check-filled { display: none; }
.card.is-learned .mark-btn .icon-check-empty { display: none; }
.card.is-learned .mark-btn .icon-check-filled { display: block; color: var(--theme-color); }
.audio-btn { background: none; border: none; cursor: pointer; color: inherit; display: flex; align-items: center; justify-content: center; padding: 4px; border-radius: 50%; transition: background 0.2s; }
.audio-btn:hover { background: rgba(0,0,0,0.05); }
body.dark-mode .audio-btn:hover { background: rgba(255,255,255,0.1); }
.word-audio { width: 32px; height: 32px; color: var(--text-sub); }
.sentence-audio { width: 100%; padding: 6px; border-radius: 4px; background: var(--bg-color); font-size: 0.85rem; font-weight: 600; justify-content: center; }
.sentence-audio:hover { background: var(--border-color); }


/* --- 组件: 前缀介绍卡片 --- */
.prefix-intro-card .card-front, .prefix-intro-card .card-back { background: var(--card-bg); }
body:not(.dark-mode) .prefix-intro-card .card-front,
body:not(.dark-mode) .prefix-intro-card .card-back { background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%); }
.prefix-intro-card .intro-title { font-size: 2.2rem; font-weight: 800; letter-spacing: 1px; font-family: 'Georgia', serif; color: var(--theme-color); }
.prefix-intro-card .card-back { display: flex; flex-direction: column; justify-content: center; gap: 2rem; }
.prefix-intro-card .intro-section { padding: 0 1rem; }
.prefix-intro-card .intro-section-title { font-size: 1.1rem; color: var(--text-main); margin-bottom: 0.5rem; border-bottom: 2px solid; padding-bottom: 0.3rem; font-weight: 700; border-color: var(--theme-color); }
.prefix-intro-card .intro-description, .prefix-intro-card .intro-imagery { font-size: 1rem; color: var(--text-sub); line-height: 1.6; }
.prefix-intro-card .intro-imagery { font-style: italic; }
.prefix-intro-card .visual-area svg { color: var(--theme-color); }


/* --- 组件: 加载动画 Spinner --- */
.spinner { animation: rotate 2s linear infinite; width: 40px; height: 40px; }
.spinner .path { stroke: var(--text-sub); stroke-linecap: round; animation: dash 1.5s ease-in-out infinite; }
@keyframes rotate { 100% { transform: rotate(360deg); } }
@keyframes dash { 0% { stroke-dasharray: 1, 150; stroke-dashoffset: 0; } 50% { stroke-dasharray: 90, 150; stroke-dashoffset: -35; } 100% { stroke-dasharray: 90, 150; stroke-dashoffset: -124; } }


/* --- 状态与动画: 洗牌 --- */
.card-grid.is-shuffling .card { opacity: 0; transform: scale(0.95); pointer-events: none; }


/* --- 组件: 骨架加载图 --- */
#skeleton-loader { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 2rem; grid-column: 1 / -1; transition: opacity 0.3s ease-out; }
.skeleton-card { height: 400px; background-color: var(--card-bg); border-radius: var(--radius-lg); box-shadow: var(--shadow); padding: 2rem 1.5rem; display: flex; flex-direction: column; justify-content: space-between; overflow: hidden; position: relative; }
.skeleton-badge, .skeleton-visual, .skeleton-word, .skeleton-hint { background-color: var(--border-color); border-radius: 4px; animation: pulse 1.5s cubic-bezier(0.4, 0, 0.6, 1) infinite; }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.6; } }
.skeleton-badge { position: absolute; top: 1rem; left: 1rem; width: 60px; height: 20px; border-radius: var(--radius-sm); }
.skeleton-visual { width: 120px; height: 120px; border-radius: 50%; margin: auto; }
.skeleton-word { width: 60%; height: 36px; margin: 0 auto 1rem; border-radius: var(--radius-sm); }
.skeleton-hint { width: 40%; height: 16px; margin: 0 auto; }


/* --- 滚动条美化 --- */
.sentence-section::-webkit-scrollbar { width: 6px; }
.sentence-section::-webkit-scrollbar-track { background: transparent; }
.sentence-section::-webkit-scrollbar-thumb { background-color: var(--border-color-hover); border-radius: 10px; }
.sentence-section::-webkit-scrollbar-thumb:hover { background-color: var(--text-sub); }