/* ==================== 全局样式 ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* 始终预留滚动条位置，避免内容高度变化时页面左右抖动 */
html {
    overflow-y: scroll;
    scrollbar-gutter: stable;
}

:root {
    /* 中性底色 - 高级且带点温暖 */
    --bg-paper: #FDFBF7;
    --bg-paper-light: #FFFFFF;
    --bg-paper-warm: #F4F1EB;

    /* 文字颜色 - 柔和的深色 */
    --text-primary: #2D3436;
    --text-secondary: #636E72;
    --text-tertiary: #B2BEC3;

    /* 强调色 - 童趣且明亮 */
    --accent-primary: #6C5CE7;
    --accent-success: #00B894;
    --accent-error: #FF7675;
    --accent-subtle: #DFE6E9;
    --accent-warning: #FDCB6E;

    /* 功能性颜色 - 用于反馈 */
    --feedback-correct: #00B894;
    --feedback-incorrect: #FF7675;

    /* 细线（用于按钮/标签轮廓） */
    --hairline: 2px solid rgba(0, 0, 0, 0.04);

    /* 圆角与阴影 - 更大、更圆润的童趣感 */
    --radius-sm: 12px;
    --radius-md: 20px;
    --radius-lg: 28px;
    --radius-pill: 9999px;
    --shadow-soft: 0 4px 12px rgba(0, 0, 0, 0.03), 0 1px 3px rgba(0, 0, 0, 0.02);
    --shadow-hover: 0 8px 24px rgba(108, 92, 231, 0.12), 0 2px 6px rgba(108, 92, 231, 0.08);
}

/* ==================== 暗黑模式 ==================== */
body.dark-mode {
    /* 深邃夜色 - 带点蓝调的深色 */
    --bg-paper: #1E1E24;
    --bg-paper-light: #2B2B36;
    --bg-paper-warm: #151519;

    /* 文字颜色 */
    --text-primary: #F5F6FA;
    --text-secondary: #DFE6E9;
    --text-tertiary: #636E72;

    /* 强调色 */
    --accent-primary: #A29BFE;
    --accent-success: #55E6C1;
    --accent-error: #FF9FF3;
    --accent-subtle: #3D3D4D;
    --accent-warning: #FFEAA7;

    /* 功能性颜色 - 用于反馈 */
    --feedback-correct: #55E6C1;
    --feedback-incorrect: #FF9FF3;

    /* 细线（用于按钮/标签轮廓） */
    --hairline: 2px solid rgba(255, 255, 255, 0.05);

    --shadow-soft: 0 4px 12px rgba(0, 0, 0, 0.2);
    --shadow-hover: 0 8px 24px rgba(162, 155, 254, 0.15);
}

/* 屏幕阅读器专用：视觉隐藏但可被辅助技术读取 */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ==================== SVG 图标样式 ==================== */
.lucide {
    width: 20px;
    height: 20px;
    vertical-align: middle;
    stroke-width: 2px;
}

.oil-icon {
    width: 1em;
    height: 1em;
    display: inline-block;
    vertical-align: -0.125em;
    object-fit: contain;
}

.icon-inline.oil-icon {
    vertical-align: -0.2em;
}

.icon-inline {
    vertical-align: -0.2em;
}

.site-brand .oil-icon {
    width: 1.5em;
    height: 1.5em;
    margin-right: 0.5rem;
}
    width: 1.1em;
    height: 1.1em;
    margin-right: 4px;
    position: relative;
    top: -1px;
}

header h1 .lucide,
.site-brand .lucide {
    width: 22px;
    height: 22px;
    margin-right: 0;
    position: relative;
    top: -1px;
}

.complete-message h2 .lucide {
    width: 32px;
    height: 32px;
    margin-right: 10px;
}

.learning-card-badge .lucide {
    width: 14px;
    height: 14px;
    margin-right: 4px;
}

body {
    font-family: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: var(--bg-paper);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 24px 20px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 640px;
    margin: 0 auto;
}

.hidden {
    display: none !important;
}

/* ==================== 头部 ==================== */
.site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 48px;
    padding: 4px 0;
}

.site-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-size: 18px;
    font-weight: 800;
    color: var(--accent-primary);
    letter-spacing: -0.01em;
    font-family: 'Nunito', sans-serif;
}

.subtitle {
    font-size: 0.95em;
    color: var(--text-secondary);
}

/* ==================== 首页 ==================== */
.home-section {
    padding: 0;
    margin-bottom: 0;
}

.home-intro {
    text-align: center;
    margin-bottom: 32px;
}

.home-eyebrow {
    display: inline-block;
    padding: 6px 16px;
    background: var(--bg-paper-light);
    border-radius: var(--radius-pill);
    font-size: 13px;
    font-weight: 800;
    color: var(--accent-primary);
    letter-spacing: 0.04em;
    text-transform: uppercase;
    margin-bottom: 16px;
    box-shadow: var(--shadow-soft);
}

.home-headline {
    font-size: clamp(2rem, 6vw, 2.5rem);
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.02em;
    line-height: 1.2;
    text-shadow: 2px 2px 0px rgba(0,0,0,0.02);
}

.home-workspace {
    background: var(--bg-paper-light);
    border: none;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
    padding: 32px 28px;
    position: relative;
    overflow: hidden;
}

.home-workspace::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 6px;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-success), var(--accent-warning));
}

.workspace-header {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 28px;
    padding-bottom: 24px;
    border-bottom: 2px dashed var(--accent-subtle);
}

.workspace-header h2 {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text-primary);
    margin: 0;
    text-align: left;
    letter-spacing: -0.01em;
}

.workspace-meta {
    font-size: 13px;
    color: var(--text-tertiary);
    white-space: nowrap;
}

.home-metrics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-bottom: 28px;
}

.metric-cell {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 20px 12px;
    background: var(--bg-paper-warm);
    border-radius: var(--radius-md);
    transition: transform 0.2s ease;
}

.metric-cell:hover {
    transform: translateY(-2px);
    background: var(--bg-paper);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
}

.metric-num {
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent-primary);
    font-variant-numeric: tabular-nums;
    letter-spacing: -0.02em;
    line-height: 1;
    font-family: 'Nunito', sans-serif;
}

.metric-label {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
}

.home-actions {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.mode-help {
    margin: 0 0 2px;
    font-size: 13px;
    color: var(--text-tertiary);
    text-align: center;
}

/* ==================== 区块样式 ==================== */
.section {
    padding: 30px 0;
    margin-bottom: 30px;
}

.section h2 {
    color: var(--text-primary);
    margin-bottom: 20px;
    text-align: center;
    font-weight: normal;
    font-size: 1.3em;
}

/* ==================== 按钮样式 ==================== */
.btn {
    padding: 12px 24px;
    border: none;
    background: transparent;
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
    outline: none;
    font-family: inherit;
    letter-spacing: 0.02em;
    border-radius: var(--radius-pill);
}

.btn:hover {
    color: var(--text-primary);
    transform: translateY(-2px);
}

.btn:active {
    background: var(--bg-paper-warm);
    transform: translateY(1px);
}

.btn:focus-visible,
.pack-tab:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}

.btn-primary {
    color: var(--accent-primary);
}

.btn-primary:hover {
    color: var(--text-primary);
}

.btn-secondary {
    color: var(--text-secondary);
}

.btn-secondary:hover {
    color: var(--text-primary);
}

.btn-toggle-active {
    color: #fff;
    background: var(--accent-primary);
    border-radius: 4px;
}

.btn-toggle-active:hover {
    color: #fff;
}

.btn-success {
    color: var(--accent-success);
}

.btn-success:hover {
    color: var(--text-primary);
}

.btn-warning {
    color: var(--accent-error);
}

.btn-warning:hover {
    color: var(--text-primary);
}

.btn-ghost {
    color: var(--text-secondary);
    border-radius: var(--radius-pill);
    background: transparent;
}

.btn-ghost:hover {
    color: var(--accent-primary);
    background: var(--bg-paper-warm);
    transform: translateY(-1px);
}

.btn-cta {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    width: 100%;
    padding: 18px 24px;
    background: var(--accent-primary);
    color: #fff;
    border-radius: var(--radius-lg);
    border: none;
    box-shadow: 0 4px 12px rgba(108, 92, 231, 0.2);
}

.btn-cta:hover {
    filter: brightness(1.05);
    color: #fff;
    box-shadow: var(--shadow-hover);
    transform: translateY(-3px);
}

.btn-cta:active {
    filter: brightness(0.95);
    background: var(--accent-primary);
    transform: translateY(1px);
    box-shadow: 0 2px 4px rgba(108, 92, 231, 0.2);
}

.btn-outline {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    width: 100%;
    padding: 16px 24px;
    background: var(--bg-paper-light);
    color: var(--text-primary);
    border: 2px solid var(--accent-subtle);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
}

.btn-outline:hover {
    background: var(--bg-paper);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
    transform: translateY(-3px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.05);
}

.btn-label {
    font-size: 15px;
    font-weight: 600;
}

.btn-desc {
    font-size: 12px;
    font-weight: 400;
    opacity: 0.7;
}

.pack-selector {
    display: flex;
    justify-content: center;

    gap: 4px;
    margin-bottom: 8px;
    padding: 4px;

    background: var(--bg-paper-warm);
    border-radius: var(--radius-pill);
    border: none;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.02);
}

.pack-tab {
    flex: 1;
    padding: 12px 20px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-family: inherit;
    font-size: 15px;
    font-weight: 700;
    cursor: pointer;
    border-radius: var(--radius-pill);
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.pack-tab:hover {
    color: var(--text-primary);
    transform: translateY(-1px);
}

.pack-tab.active {
    color: var(--accent-primary);
    background: var(--bg-paper-light);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    transform: translateY(-1px);
}

.pack-help {
    margin: 0 0 20px;
    font-size: 13px;
    color: var(--text-tertiary);
    text-align: center;
}

/* ==================== 加载动画 ==================== */
.loading {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.spinner {
    width: 48px;
    height: 48px;
    margin: 0 auto 24px;
    border: 4px solid var(--accent-subtle);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    animation: spin 1s cubic-bezier(0.68, -0.55, 0.265, 1.55) infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ==================== 统计信息 ==================== */
.stats {
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 30px;
    padding: 20px 0;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 80px;
}

.stat-label {
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-size: 1.75em;
    font-weight: 800;
    color: var(--text-primary);
    font-family: 'Nunito', sans-serif;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--accent-subtle);
    margin-top: 15px;
    overflow: hidden;
    border-radius: var(--radius-pill);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-success));
    transition: width 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    border-radius: var(--radius-pill);
}

/* ==================== 单词显示 ==================== */
.word-display {
    text-align: center;
    padding: 60px 20px;
}

.chinese-word {
    font-size: 3em;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 24px;
    animation: fadeIn 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
    letter-spacing: 0.02em;
    text-shadow: 2px 2px 0px rgba(0,0,0,0.05);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ==================== 输入区域 ==================== */
.input-area {
    margin: 40px 0;
    position: relative;
}

#word-input {
    width: 100%;
    padding: 20px 24px;
    font-size: 28px;
    font-weight: 700;
    border: 3px solid var(--accent-subtle);
    border-radius: var(--radius-pill);
    text-align: center;
    outline: none;
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
    font-family: 'Nunito', 'SF Mono', 'Consolas', monospace;
    letter-spacing: 0.05em;
    background: var(--bg-paper-light);
    color: var(--text-primary);
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.02);
}

#word-input:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 4px rgba(108, 92, 231, 0.15);
    transform: translateY(-2px);
}

#word-input:focus-visible {
    border-color: var(--accent-primary);
    outline: none;
}

#word-input.correct {
    border-color: var(--feedback-correct);
    color: var(--feedback-correct);
    background: rgba(0, 184, 148, 0.05);
    box-shadow: 0 0 0 4px rgba(0, 184, 148, 0.15);
}

#word-input.incorrect {
    border-color: var(--feedback-incorrect);
    color: var(--feedback-incorrect);
    background: rgba(255, 118, 117, 0.05);
    box-shadow: 0 0 0 4px rgba(255, 118, 117, 0.15);
    animation: shake 0.5s cubic-bezier(0.36, 0.07, 0.19, 0.97) both;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

@media (prefers-reduced-motion: reduce) {
    #word-input.incorrect {
        animation: none;
    }

    .btn,
    .pack-tab,
    #word-input {
        transition: none;
    }
}

.input-feedback {
    text-align: center;
    margin-top: 15px;
    min-height: 24px;
    font-size: 14px;
}

.feedback-correct {
    color: var(--feedback-correct);
    font-weight: normal;
}

.feedback-incorrect {
    color: var(--feedback-incorrect);
    font-weight: normal;
}

/* ==================== 控制按钮 ==================== */
.control-buttons {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.btn-icon {
    padding: 12px;
    min-width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    border-radius: 50%;
    background: var(--bg-paper-light);
    box-shadow: var(--shadow-soft);
    color: var(--text-secondary);
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.btn-icon:hover {
    color: var(--accent-primary);
    transform: translateY(-2px) scale(1.05);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.btn-icon:active {
    transform: translateY(1px) scale(0.95);
}

/* ==================== 答案显示 ==================== */
.answer-display {
    margin-top: 30px;
    padding: 30px 0;
    text-align: center;
}

.answer-display.learning-card-area:hover .learning-card {
    box-shadow: 0 0 0 1px var(--accent-primary);
}

.correct-answer {
    margin-bottom: 12px;
    font-size: 16px;
}

.answer-label {
    color: var(--text-secondary);
    margin-right: 8px;
}

.word-text {
    font-size: 24px;
    font-weight: 800;
    color: var(--accent-primary);
    font-family: 'Nunito', 'SF Mono', 'Consolas', monospace;
    letter-spacing: 0.05em;
}

/* ==================== 完成界面 ==================== */
.complete-message {
    text-align: center;
    padding: 60px 20px;
}

.complete-message h2 {
    color: var(--accent-primary);
    font-size: 2.5em;
    margin-bottom: 30px;
    font-weight: 800;
    text-shadow: 2px 2px 0px rgba(0,0,0,0.05);
}

.complete-stats {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin: 40px 0;
}

.complete-stats .stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.complete-stats .stat-value {
    font-size: 2.5em;
    font-weight: 800;
    color: var(--text-primary);
    font-family: 'Nunito', sans-serif;
}

.complete-stats .stat-name {
    font-size: 13px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.complete-subtitle {
    color: var(--text-secondary);
    font-size: 15px;
    margin: -16px 0 24px;
}

.complete-word-breakdown {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin: 0 0 40px;
    padding: 24px 32px;
    background: var(--bg-paper-warm);
    border-radius: var(--radius-lg);
    max-width: 400px;
    margin-left: auto;
    margin-right: auto;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.02);
}

.breakdown-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
}

.breakdown-value {
    font-size: 1.75em;
    font-weight: 800;
    color: var(--accent-primary);
    font-family: 'Nunito', sans-serif;
}

.breakdown-label {
    font-size: 13px;
    color: var(--text-secondary);
}

.complete-actions {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

/* ==================== 学习模式 ==================== */
.learning-mode {
    text-align: center;
    animation: fadeIn 0.4s ease;
}

.learning-badge {
    display: inline-block;
    padding: 6px 16px;
    font-size: 13px;
    font-weight: 800;
    margin-bottom: 24px;
    color: var(--accent-primary);
    background: rgba(108, 92, 231, 0.1);
    border-radius: var(--radius-pill);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.word-pair {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    margin: 24px 0;
    font-size: 20px;
    background: var(--bg-paper-light);
    padding: 20px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-soft);
}

.word-pair .chinese {
    color: var(--text-primary);
    font-weight: 700;
}

.word-pair .arrow {
    color: var(--accent-subtle);
    font-size: 20px;
}

.word-pair .english {
    color: var(--accent-primary);
    font-weight: 800;
    font-size: 24px;
    font-family: 'Nunito', 'SF Mono', 'Consolas', monospace;
}

.learning-hint {
    color: var(--text-secondary);
    font-size: 14px;
    margin-top: 15px;
}

/* ==================== 单词列表 ==================== */
#word-list-content {
    max-height: 500px;
    overflow-y: auto;
}

.word-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px;
    margin-bottom: 8px;
    background: var(--bg-paper-light);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-soft);
    transition: transform 0.2s ease;
}

.word-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.word-item .english {
    font-weight: 800;
    color: var(--accent-primary);
    font-family: 'Nunito', 'SF Mono', monospace;
    font-size: 1.1em;
}

.word-item .chinese {
    color: var(--text-secondary);
    font-weight: 600;
}

.word-item .status {
    padding: 6px 12px;
    font-size: 11px;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: var(--radius-pill);
}

.status-new {
    background: var(--bg-paper-warm);
    color: var(--text-secondary);
}

.status-learning {
    background: rgba(108, 92, 231, 0.1);
    color: var(--accent-primary);
}

.status-mastered {
    background: rgba(0, 184, 148, 0.1);
    color: var(--accent-success);
}

.status-mistake {
    background: rgba(255, 118, 117, 0.1);
    color: var(--accent-error);
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 600px) {
    body {
        padding: 16px;
    }

    .site-header {
        margin-bottom: 32px;
    }

    .home-workspace {
        padding: 20px 16px;
    }

    .home-metrics {
        gap: 8px;
    }

    .metric-cell {
        padding: 12px 4px;
    }

    .metric-num {
        font-size: 1.5rem;
    }

    .workspace-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 4px;
    }

    .chinese-word {
        font-size: 2em;
    }

    #word-input {
        font-size: 18px;
        padding: 14px;
    }

    .complete-stats {
        flex-direction: column;
        gap: 30px;
    }

    .complete-word-breakdown {
        flex-direction: row;
        gap: 24px;
        padding: 16px;
    }

    .stats {
        flex-direction: column;
        gap: 15px;
    }
}

/* ==================== 暗黑模式优化 ==================== */

/* 暗黑模式下的学习卡片背景 */
body.dark-mode .learning-card.permanent {
    background: var(--bg-paper-light);
}

body.dark-mode .complete-word-breakdown {
    background: var(--bg-paper-light);
}

/* 暗黑模式下的动态样式（使用JS注入的样式需要适配） */
body.dark-mode .char-correct {
    color: var(--feedback-correct);
}

body.dark-mode .char-incorrect {
    color: var(--feedback-incorrect);
}

body.dark-mode .char-empty {
    color: var(--text-tertiary);
}

body.dark-mode .hint-mode {
    border-color: var(--accent-primary) !important;
}

body.dark-mode .learning-card-badge {
    color: var(--accent-primary);
}

body.dark-mode .word-item-large .label {
    color: var(--text-secondary);
}

body.dark-mode .chinese-large,
body.dark-mode .english-large {
    color: var(--text-primary);
}

body.dark-mode .arrow-large {
    color: var(--text-tertiary);
}

body.dark-mode .learning-card-hint {
    color: var(--text-secondary);
}

/* 主题切换按钮动画 */
#theme-toggle {
    transition: transform 0.3s ease;
}

#theme-toggle:hover {
    transform: rotate(15deg) scale(1.1);
}

/* 主题切换时的平滑过渡 */
body,
.btn,
#word-input,
.stat-value,
.word-text,
.chinese-word {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}