/* ==================== 基础变量与重置 ==================== */
:root {
    --primary: #4CAF50;
    --primary-light: #81C784;
    --primary-dark: #388E3C;
    --bg: #f0f7f0;
    --surface: #ffffff;
    --text: #2c3e50;
    --text-secondary: #666;
    --border: #e0e0e0;
    --shadow: rgba(0,0,0,0.08);
    --correct: #4CAF50;
    --wrong: #f44336;
    --radius: 16px;
    --radius-sm: 10px;
    --header-bg: #4CAF50;
    --header-text: #fff;
    --input-bg: #fff;
    --card-hover: #f5f5f5;
    --accent: #FF9800;
}

/* 黑白简洁风 */
[data-theme="black"] {
    --primary: #333;
    --primary-light: #666;
    --primary-dark: #111;
    --bg: #fafafa;
    --surface: #fff;
    --text: #222;
    --text-secondary: #888;
    --border: #ddd;
    --shadow: rgba(0,0,0,0.06);
    --correct: #333;
    --wrong: #e74c3c;
    --header-bg: #333;
    --header-text: #fff;
    --input-bg: #fff;
    --card-hover: #f0f0f0;
    --accent: #555;
}

/* 粉白可爱萌风 */
[data-theme="pink"] {
    --primary: #FF8BA7;
    --primary-light: #FFB3C6;
    --primary-dark: #E85D75;
    --bg: #FFF0F3;
    --surface: #fff;
    --text: #5D3A3A;
    --text-secondary: #9E7A7A;
    --border: #FFD6E0;
    --shadow: rgba(255,139,167,0.12);
    --correct: #FF8BA7;
    --wrong: #FF6B6B;
    --header-bg: #FF8BA7;
    --header-text: #fff;
    --input-bg: #FFF5F7;
    --card-hover: #FFF0F3;
    --accent: #FFD93D;
}

/* 清爽绿白风（默认） */
[data-theme="green"] {
    --primary: #4CAF50;
    --primary-light: #81C784;
    --primary-dark: #388E3C;
    --bg: #f0f7f0;
    --surface: #ffffff;
    --text: #2c3e50;
    --text-secondary: #666;
    --border: #e0e0e0;
    --shadow: rgba(0,0,0,0.08);
    --correct: #4CAF50;
    --wrong: #f44336;
    --header-bg: #4CAF50;
    --header-text: #fff;
    --input-bg: #fff;
    --card-hover: #f5f5f5;
    --accent: #FF9800;
}

/* 小孩哥蓝白风 */
[data-theme="blue"] {
    --primary: #2196F3;
    --primary-light: #64B5F6;
    --primary-dark: #1976D2;
    --bg: #E3F2FD;
    --surface: #fff;
    --text: #1a237e;
    --text-secondary: #5c6bc0;
    --border: #BBDEFB;
    --shadow: rgba(33,150,243,0.1);
    --correct: #2196F3;
    --wrong: #f44336;
    --header-bg: #2196F3;
    --header-text: #fff;
    --input-bg: #fff;
    --card-hover: #E3F2FD;
    --accent: #FF9800;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

html, body {
    height: 100%;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    overflow-x: hidden;
}

#app {
    min-height: 100vh;
    max-width: 600px;
    margin: 0 auto;
    position: relative;
}

/* ==================== 页面切换 ==================== */
.page {
    display: none;
    min-height: 100vh;
    animation: fadeIn 0.3s ease;
}

.page.active {
    display: block;
}

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

/* ==================== 认证页面 ==================== */
#auth-page {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.auth-container {
    width: 100%;
    max-width: 360px;
    text-align: center;
}

.logo {
    font-size: 72px;
    margin-bottom: 10px;
}

.auth-container h1 {
    font-size: 26px;
    margin-bottom: 6px;
    color: var(--text);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 30px;
}

.auth-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    background: var(--surface);
    border-radius: var(--radius);
    padding: 4px;
    box-shadow: 0 2px 8px var(--shadow);
}

.auth-tab {
    flex: 1;
    padding: 12px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s;
}

.auth-tab.active {
    background: var(--primary);
    color: #fff;
}

.auth-form {
    display: none;
    flex-direction: column;
    gap: 14px;
}

.auth-form.active {
    display: flex;
}

.auth-form input {
    padding: 14px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 16px;
    background: var(--input-bg);
    color: var(--text);
    outline: none;
    transition: border-color 0.2s;
}

.auth-form input:focus {
    border-color: var(--primary);
}

.btn-primary {
    padding: 14px 24px;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--primary);
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 4px 12px var(--shadow);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px var(--shadow);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    padding: 14px 24px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--surface);
    color: var(--text);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

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

.auth-tip {
    margin-top: 20px;
    color: var(--text-secondary);
    font-size: 13px;
}

/* ==================== 头部 ==================== */
.app-header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    background: var(--header-bg);
    color: var(--header-text);
    box-shadow: 0 2px 8px var(--shadow);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo-small {
    font-size: 24px;
}

.app-title {
    font-size: 18px;
    font-weight: 700;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 14px;
}

.btn-icon {
    width: 36px;
    height: 36px;
    border: none;
    border-radius: 50%;
    background: rgba(255,255,255,0.2);
    color: var(--header-text);
    font-size: 16px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s;
}

.btn-icon:hover {
    background: rgba(255,255,255,0.35);
}

.page-title {
    font-size: 17px;
    font-weight: 600;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
}

.btn-text {
    border: none;
    background: rgba(255,255,255,0.2);
    color: var(--header-text);
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    cursor: pointer;
}

/* ==================== 主内容区 ==================== */
.main-content {
    padding: 16px;
    padding-bottom: 40px;
}

.section {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 18px;
    margin-bottom: 16px;
    box-shadow: 0 2px 12px var(--shadow);
}

.section h2 {
    font-size: 17px;
    margin-bottom: 14px;
    color: var(--text);
}

/* 模式选择 */
.mode-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
}

.mode-card {
    padding: 18px 12px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    background: var(--surface);
}

.mode-card:hover {
    border-color: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.mode-card.selected {
    border-color: var(--primary);
    background: var(--card-hover);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.mode-icon {
    font-size: 32px;
    margin-bottom: 8px;
}

.mode-name {
    font-size: 15px;
    font-weight: 700;
    margin-bottom: 4px;
}

.mode-desc {
    font-size: 12px;
    color: var(--text-secondary);
}

/* 配置区 */
.config-row {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 14px;
    flex-wrap: wrap;
}

.config-row label {
    font-size: 14px;
    font-weight: 600;
    min-width: 80px;
}

.count-presets {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.count-btn {
    padding: 8px 16px;
    border: 2px solid var(--border);
    border-radius: 20px;
    background: var(--surface);
    color: var(--text);
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s;
}

.count-btn.active {
    border-color: var(--primary);
    background: var(--primary);
    color: #fff;
}

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

#custom-count {
    width: 80px;
    padding: 10px 12px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    text-align: center;
    background: var(--input-bg);
    color: var(--text);
    outline: none;
}

#custom-count:focus {
    border-color: var(--primary);
}

/* 开始按钮 */
.btn-start {
    width: 100%;
    padding: 16px;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--primary);
    color: #fff;
    font-size: 18px;
    font-weight: 700;
    cursor: pointer;
    margin-bottom: 16px;
    box-shadow: 0 4px 16px var(--shadow);
    transition: all 0.2s;
}

.btn-start:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--shadow);
}

/* 快捷入口 */
.quick-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.quick-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 16px 8px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--surface);
    color: var(--text);
    font-size: 13px;
    cursor: pointer;
    transition: all 0.2s;
}

.quick-btn:hover {
    border-color: var(--primary);
    background: var(--card-hover);
}

.quick-icon {
    font-size: 28px;
}

/* ==================== 练习页面 ==================== */
.practice-content {
    padding: 16px;
    padding-bottom: 40px;
}

.timer {
    font-size: 14px;
    font-weight: 600;
    background: rgba(255,255,255,0.2);
    padding: 4px 10px;
    border-radius: 20px;
}

.question-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px;
    margin-bottom: 12px;
    background: var(--surface);
    border-radius: var(--radius-sm);
    box-shadow: 0 2px 8px var(--shadow);
}

.question-num {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-light);
    color: #fff;
    border-radius: 50%;
    font-size: 14px;
    font-weight: 700;
    flex-shrink: 0;
}

.question-text {
    font-size: 18px;
    font-weight: 600;
    min-width: 100px;
}

.question-input {
    flex: 1;
    padding: 12px 14px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 18px;
    text-align: center;
    background: var(--input-bg);
    color: var(--text);
    outline: none;
    transition: border-color 0.2s;
    max-width: 120px;
}

.question-input:focus {
    border-color: var(--primary);
}

.question-input.correct-answer {
    border-color: var(--correct);
    background: rgba(76, 175, 80, 0.1);
}

.question-input.wrong-answer {
    border-color: var(--wrong);
    background: rgba(244, 67, 54, 0.1);
}

.answer-mark {
    font-size: 24px;
    width: 32px;
    text-align: center;
    flex-shrink: 0;
}

.correct-mark {
    color: var(--correct);
}

.wrong-mark {
    color: var(--wrong);
}

.btn-large {
    width: 100%;
    padding: 16px;
    font-size: 18px;
    margin-top: 10px;
}

/* ==================== 结果页面 ==================== */
.result-content {
    padding: 20px;
    padding-bottom: 40px;
}

.result-card {
    text-align: center;
    padding: 30px 20px;
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: 0 2px 12px var(--shadow);
    margin-bottom: 20px;
}

.score-circle {
    width: 120px;
    height: 120px;
    margin: 0 auto 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: var(--primary);
    color: #fff;
    font-size: 48px;
    font-weight: 800;
    box-shadow: 0 4px 16px var(--shadow);
}

.score-label {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
}

.result-message {
    margin-top: 12px;
    font-size: 16px;
    color: var(--text-secondary);
}

.result-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-bottom: 20px;
}

.stat-item {
    text-align: center;
    padding: 14px 8px;
    background: var(--surface);
    border-radius: var(--radius-sm);
    box-shadow: 0 2px 8px var(--shadow);
}

.stat-item.correct .stat-value {
    color: var(--correct);
}

.stat-item.wrong .stat-value {
    color: var(--wrong);
}

.stat-value {
    font-size: 22px;
    font-weight: 800;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 12px;
    color: var(--text-secondary);
}

.result-details {
    margin-bottom: 20px;
}

.result-detail-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    margin-bottom: 8px;
    background: var(--surface);
    border-radius: var(--radius-sm);
    box-shadow: 0 1px 6px var(--shadow);
    font-size: 15px;
}

.result-detail-item .detail-mark {
    font-size: 20px;
    width: 28px;
    text-align: center;
}

.result-detail-item .detail-question {
    flex: 1;
}

.result-detail-item .detail-user {
    color: var(--wrong);
    text-decoration: line-through;
    margin-right: 8px;
}

.result-detail-item .detail-correct {
    color: var(--correct);
    font-weight: 700;
}

.result-actions {
    display: flex;
    gap: 12px;
}

.result-actions button {
    flex: 1;
}

/* ==================== 错题本 ==================== */
.wrong-content, .records-content, .theme-content {
    padding: 16px;
    padding-bottom: 40px;
}

.wrong-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px;
    margin-bottom: 10px;
    background: var(--surface);
    border-radius: var(--radius-sm);
    box-shadow: 0 2px 8px var(--shadow);
    position: relative;
}

.wrong-question {
    flex: 1;
    font-size: 16px;
    font-weight: 600;
}

.wrong-answers {
    font-size: 14px;
    color: var(--text-secondary);
}

.wrong-answers .wa-wrong {
    color: var(--wrong);
    text-decoration: line-through;
    margin-right: 6px;
}

.wrong-answers .wa-correct {
    color: var(--correct);
    font-weight: 700;
}

.wrong-delete {
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 18px;
    cursor: pointer;
    padding: 4px;
}

.wrong-delete:hover {
    color: var(--wrong);
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-icon {
    font-size: 64px;
    margin-bottom: 16px;
}

.empty-state p {
    font-size: 16px;
}

/* ==================== 练习记录 ==================== */
.record-item {
    padding: 14px;
    margin-bottom: 10px;
    background: var(--surface);
    border-radius: var(--radius-sm);
    box-shadow: 0 2px 8px var(--shadow);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.record-left {
    flex: 1;
}

.record-mode {
    font-size: 15px;
    font-weight: 700;
    margin-bottom: 4px;
}

.record-meta {
    font-size: 12px;
    color: var(--text-secondary);
}

.record-score {
    font-size: 24px;
    font-weight: 800;
    color: var(--primary);
}

/* ==================== 主题切换 ==================== */
.theme-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 14px;
}

.theme-card {
    padding: 14px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    background: var(--surface);
}

.theme-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.theme-card.selected {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.theme-preview {
    width: 100%;
    height: 80px;
    border-radius: var(--radius-sm);
    margin-bottom: 10px;
    border: 1px solid var(--border);
}

.theme-black { background: #fafafa; }
.theme-pink { background: #FFF0F3; }
.theme-green { background: #f0f7f0; }
.theme-blue { background: #E3F2FD; }

.theme-name {
    font-size: 14px;
    font-weight: 700;
    margin-bottom: 4px;
}

.theme-desc {
    font-size: 12px;
    color: var(--text-secondary);
}

/* ==================== Toast & Loading ==================== */
.toast {
    position: fixed;
    bottom: 80px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: rgba(0,0,0,0.8);
    color: #fff;
    padding: 12px 24px;
    border-radius: 24px;
    font-size: 14px;
    z-index: 1000;
    opacity: 0;
    transition: all 0.3s;
    pointer-events: none;
    white-space: nowrap;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255,255,255,0.8);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 999;
}

.loading-overlay.active {
    display: flex;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ==================== 响应式 ==================== */
@media (min-width: 768px) {
    #app {
        max-width: 680px;
    }

    .mode-grid {
        grid-template-columns: repeat(4, 1fr);
    }

    .quick-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .theme-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .result-stats {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 360px) {
    .mode-grid {
        grid-template-columns: 1fr;
    }

    .quick-grid {
        grid-template-columns: 1fr;
    }

    .theme-grid {
        grid-template-columns: 1fr;
    }

    .result-stats {
        grid-template-columns: repeat(2, 1fr);
    }

    .question-item {
        flex-wrap: wrap;
    }

    .question-text {
        min-width: auto;
    }
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}