/* ============================================
   Excel学习平台 - 样式表
   风格：活泼学生风 · 明亮配色
   ============================================ */

/* ---------- CSS变量 ---------- */
:root {
    --primary: #4A90D9;
    --primary-light: #6BA5E7;
    --primary-dark: #3A7BC8;
    --green: #52C41A;
    --green-light: #b7eb8f;
    --green-bg: #f6ffed;
    --blue: #1890FF;
    --blue-light: #91d5ff;
    --blue-bg: #e6f7ff;
    --orange: #FA8C16;
    --orange-light: #ffd591;
    --orange-bg: #fff7e6;
    --coral: #FF6B6B;
    --coral-light: #ffa39e;
    --coral-bg: #fff1f0;
    --purple: #722ED1;
    --purple-light: #d3adf7;
    --purple-bg: #f9f0ff;
    --pink: #EB2F96;
    --pink-light: #ffadd2;
    --pink-bg: #fff0f6;
    --yellow: #FADB14;
    --yellow-bg: #feffe6;
    --bg: #F5F7FA;
    --white: #FFFFFF;
    --text: #2c3e50;
    --text-light: #5a6d80;
    --text-lighter: #95a5b8;
    --border: #e8ecf1;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --font: 'PingFang SC','Microsoft YaHei','Helvetica Neue',Arial,sans-serif;
    --transition: all 0.3s ease;
}

/* ---------- 重置 ---------- */
*,*::before,*::after { margin:0; padding:0; box-sizing:border-box; }
html { scroll-behavior: smooth; }
body { font-family: var(--font); background: var(--bg); color: var(--text); line-height:1.7; }
a { text-decoration:none; color:inherit; }
ul { list-style:none; }
img { max-width:100%; }
button { cursor:pointer; border:none; font-family:var(--font); }

/* ---------- 容器 ---------- */
.container { max-width:1200px; margin:0 auto; padding:0 20px; }

/* ---------- 导航栏 ---------- */
.navbar {
    background: var(--white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
}
.nav-flex {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}
.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}
.menu-toggle {
    display: none;
    background: none;
    font-size: 1.5rem;
    color: var(--text);
    padding: 5px;
}
.nav-links {
    display: flex;
    gap: 4px;
}
.nav-links a {
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
    white-space: nowrap;
}
.nav-links a:hover { background: var(--bg); color: var(--primary); }
.nav-links a.active { background: var(--primary); color: var(--white); }

/* ---------- Hero横幅 ---------- */
.hero {
    background: linear-gradient(135deg, #4A90D9 0%, #6366f1 50%, #8b5cf6 100%);
    color: var(--white);
    padding: 80px 0 100px;
    position: relative;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 500px;
    height: 500px;
    background: rgba(255,255,255,0.08);
    border-radius: 50%;
}
.hero::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 400px;
    height: 400px;
    background: rgba(255,255,255,0.05);
    border-radius: 50%;
}
.hero-content { position: relative; z-index: 1; text-align: center; }
.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,0.2);
    padding: 6px 20px;
    border-radius: 30px;
    font-size: 0.9rem;
    margin-bottom: 20px;
    backdrop-filter: blur(10px);
}
.hero h1 { font-size: 2.8rem; margin-bottom: 16px; text-shadow: 0 2px 10px rgba(0,0,0,0.2); }
.hero-desc { font-size: 1.15rem; opacity: 0.95; line-height: 1.8; margin-bottom: 30px; }
.hero-stats {
    display: flex;
    justify-content: center;
    gap: 50px;
    margin-bottom: 35px;
}
.stat-item { text-align: center; }
.stat-num { display: block; font-size: 2rem; font-weight: 800; }
.stat-label { font-size: 0.85rem; opacity: 0.85; }
.hero-wave { position: absolute; bottom: -1px; left: 0; width: 100%; }
.hero-wave svg { display: block; width: 100%; height: 60px; }

/* ---------- 按钮 ---------- */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: 600;
    transition: var(--transition);
    text-align: center;
}
.btn-hero {
    background: var(--yellow);
    color: #333;
    box-shadow: 0 4px 15px rgba(250,219,20,0.4);
}
.btn-hero:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(250,219,20,0.5); }
.btn-primary {
    background: var(--primary);
    color: var(--white);
}
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-1px); }
.btn-success {
    background: var(--green);
    color: var(--white);
}
.btn-download {
    background: linear-gradient(135deg, var(--green), #73d13d);
    color: var(--white);
    padding: 10px 24px;
    border-radius: 8px;
    font-size: 0.9rem;
    cursor: pointer;
    border: none;
    font-family: var(--font);
    font-weight: 600;
}
.btn-download:hover { transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-quiz {
    background: linear-gradient(135deg, var(--primary), #6366f1);
    color: var(--white);
    padding: 12px 36px;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    font-family: var(--font);
    font-weight: 600;
}
.btn-quiz:hover { transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-retry {
    background: var(--orange);
    color: var(--white);
    padding: 10px 24px;
    border-radius: 8px;
    font-size: 0.9rem;
    cursor: pointer;
    border: none;
    font-family: var(--font);
    font-weight: 600;
    margin-top: 10px;
}

/* ---------- 章节标题 ---------- */
.section { padding: 60px 0; }
.section-title {
    font-size: 1.8rem;
    text-align: center;
    margin-bottom: 8px;
    color: var(--text);
}
.section-desc {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 40px;
    font-size: 1.05rem;
}

/* ---------- 模块卡片网格 ---------- */
.modules-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.module-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: 30px 24px;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    border: 2px solid transparent;
    display: block;
}
.module-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}
.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
}
.card-green::before { background: var(--green); }
.card-green:hover { border-color: var(--green-light); }
.card-blue::before { background: var(--blue); }
.card-blue:hover { border-color: var(--blue-light); }
.card-orange::before { background: var(--orange); }
.card-orange:hover { border-color: var(--orange-light); }
.card-coral::before { background: var(--coral); }
.card-coral:hover { border-color: var(--coral-light); }
.card-purple::before { background: var(--purple); }
.card-purple:hover { border-color: var(--purple-light); }
.card-pink::before { background: var(--pink); }
.card-pink:hover { border-color: var(--pink-light); }

.card-icon { font-size: 2.5rem; margin-bottom: 12px; }
.card-badge {
    display: inline-block;
    padding: 3px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 10px;
}
.card-green .card-badge { background: var(--green-bg); color: var(--green); }
.card-blue .card-badge { background: var(--blue-bg); color: var(--blue); }
.card-orange .card-badge { background: var(--orange-bg); color: var(--orange); }
.card-coral .card-badge { background: var(--coral-bg); color: var(--coral); }
.card-purple .card-badge { background: var(--purple-bg); color: var(--purple); }
.card-pink .card-badge { background: var(--pink-bg); color: var(--pink); }

.module-card h3 { font-size: 1.15rem; margin-bottom: 8px; }
.module-card p { color: var(--text-light); font-size: 0.9rem; line-height: 1.6; }
.card-meta {
    display: flex;
    gap: 16px;
    margin-top: 16px;
    font-size: 0.8rem;
    color: var(--text-lighter);
}
.card-arrow {
    position: absolute;
    bottom: 20px;
    right: 20px;
    font-size: 1.5rem;
    color: var(--text-lighter);
    transition: var(--transition);
}
.module-card:hover .card-arrow { transform: translateX(5px); color: var(--primary); }
.card-locked { opacity: 0.7; cursor: default; }
.card-locked:hover { transform: none; box-shadow: var(--shadow-sm); }
.card-lock {
    margin-top: 16px;
    padding: 6px 16px;
    background: var(--bg);
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-lighter);
    display: inline-block;
}

/* ---------- 学习路径 ---------- */
.path-container { max-width: 700px; margin: 0 auto; position: relative; }
.path-container::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(to bottom, var(--green), var(--blue), var(--orange), var(--purple));
    border-radius: 3px;
}
.path-item {
    display: flex;
    align-items: flex-start;
    gap: 24px;
    padding: 20px 0;
    position: relative;
}
.path-dot {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 4px solid var(--white);
    box-shadow: var(--shadow-sm);
    z-index: 1;
}
.path-green .path-dot { background: var(--green); }
.path-blue .path-dot { background: var(--blue); }
.path-orange .path-dot { background: var(--orange); }
.path-purple .path-dot { background: var(--purple); }
.path-content {
    background: var(--white);
    padding: 20px 24px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    flex: 1;
}
.path-content h4 { margin-bottom: 6px; font-size: 1.05rem; }
.path-content p { color: var(--text-light); font-size: 0.9rem; }

/* ---------- 特色卡片 ---------- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
.feature-card {
    background: var(--white);
    padding: 28px 24px;
    border-radius: var(--radius-md);
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}
.feature-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.feature-icon { font-size: 2.2rem; margin-bottom: 12px; }
.feature-card h4 { margin-bottom: 8px; font-size: 1rem; }
.feature-card p { color: var(--text-light); font-size: 0.85rem; }

/* ---------- 页脚 ---------- */
.footer {
    background: var(--text);
    color: rgba(255,255,255,0.7);
    text-align: center;
    padding: 30px 20px;
    font-size: 0.85rem;
    line-height: 2;
}

/* ============================================
   模块页面样式
   ============================================ */

/* ---------- 模块头部 ---------- */
.module-hero {
    padding: 50px 0 70px;
    color: var(--white);
    position: relative;
    overflow: hidden;
}
.module-hero-green { background: linear-gradient(135deg, #52C41A, #73d13d, #389e0d); }
.module-hero-blue { background: linear-gradient(135deg, #1890FF, #40a9ff, #096dd9); }
.module-hero h1 { font-size: 2.2rem; margin-bottom: 10px; }
.module-hero p { opacity: 0.9; font-size: 1.05rem; }
.module-hero .hero-wave { position: absolute; bottom: -1px; left: 0; width: 100%; }
.module-hero .hero-wave svg { display: block; width: 100%; height: 50px; }

/* ---------- 模块进度 ---------- */
.module-progress {
    background: var(--white);
    border-radius: var(--radius-md);
    padding: 20px 24px;
    margin: -30px auto 30px;
    max-width: 800px;
    box-shadow: var(--shadow-md);
    position: relative;
    z-index: 10;
}
.progress-bar-bg {
    background: var(--bg);
    border-radius: 10px;
    height: 12px;
    overflow: hidden;
    margin-top: 10px;
}
.progress-bar-fill {
    height: 100%;
    border-radius: 10px;
    background: linear-gradient(90deg, var(--green), #73d13d);
    transition: width 0.5s ease;
}
.progress-text { font-size: 0.9rem; color: var(--text-light); }
.progress-text span { font-weight: 700; color: var(--green); }

/* ---------- 课次手风琴 ---------- */
.lesson-list { max-width: 900px; margin: 0 auto; padding-bottom: 60px; }

.lesson-card {
    background: var(--white);
    border-radius: var(--radius-md);
    margin-bottom: 16px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    border: 2px solid transparent;
    transition: var(--transition);
}
.lesson-card.active { border-color: var(--green-light); box-shadow: var(--shadow-md); }

.lesson-header {
    display: flex;
    align-items: center;
    padding: 18px 24px;
    cursor: pointer;
    gap: 16px;
    transition: var(--transition);
    user-select: none;
}
.lesson-header:hover { background: var(--green-bg); }
.lesson-num {
    background: var(--green);
    color: var(--white);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.85rem;
    flex-shrink: 0;
}
.lesson-header h3 { flex: 1; font-size: 1.05rem; }
.lesson-toggle {
    font-size: 1.2rem;
    transition: transform 0.3s ease;
    color: var(--text-lighter);
}
.lesson-card.active .lesson-toggle { transform: rotate(180deg); color: var(--green); }

.lesson-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
}
.lesson-body-inner { padding: 0 24px 24px; }

/* ---------- 内容区块 ---------- */
.content-block {
    margin-bottom: 24px;
    padding: 20px;
    border-radius: var(--radius-sm);
    border-left: 4px solid;
}
.block-knowledge { background: #f0f9ff; border-color: var(--blue); }
.block-steps { background: var(--green-bg); border-color: var(--green); }
.block-tips { background: var(--yellow-bg); border-color: var(--yellow); }
.block-errors { background: var(--coral-bg); border-color: var(--coral); }
.block-practice { background: var(--purple-bg); border-color: var(--purple); }
.block-challenge { background: var(--orange-bg); border-color: var(--orange); }
.block-norm { background: var(--pink-bg); border-color: var(--pink); }

.content-block h4 { margin-bottom: 12px; font-size: 1.05rem; }
.content-block h5 { margin: 14px 0 8px; font-size: 0.95rem; color: var(--text); }
.content-block ul { padding-left: 20px; }
.content-block li { margin-bottom: 6px; font-size: 0.9rem; color: var(--text-light); list-style: disc; }
.content-block li strong { color: var(--text); }
.content-block p { font-size: 0.9rem; color: var(--text-light); margin-bottom: 8px; }
.content-block ol { padding-left: 20px; }
.content-block ol li { list-style: decimal; }

/* ---------- 概念卡 ---------- */
.concept-cards { display: grid; grid-template-columns: repeat(3,1fr); gap: 12px; margin: 12px 0; }
.concept-card {
    background: var(--white);
    padding: 16px;
    border-radius: var(--radius-sm);
    text-align: center;
    box-shadow: var(--shadow-sm);
}
.concept-card h6 { font-size: 0.95rem; margin-bottom: 6px; }
.concept-card p { font-size: 0.8rem; color: var(--text-light); }

/* ---------- Excel界面演示 ---------- */
.excel-demo {
    background: var(--white);
    border: 2px solid #d4d4d4;
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin: 14px 0;
    font-size: 0.8rem;
}
.excel-titlebar {
    background: #217346;
    color: var(--white);
    padding: 6px 12px;
    font-size: 0.75rem;
}
.excel-tabs {
    background: #f3f3f3;
    padding: 4px 12px;
    display: flex;
    gap: 2px;
    border-bottom: 1px solid #d4d4d4;
}
.excel-tabs span {
    padding: 4px 10px;
    font-size: 0.7rem;
    cursor: default;
    border-radius: 4px 4px 0 0;
}
.excel-tabs span.etab-active { background: var(--white); border: 1px solid #d4d4d4; border-bottom: none; }
.excel-formula-bar {
    display: flex;
    border-bottom: 1px solid #d4d4d4;
    align-items: center;
    font-size: 0.75rem;
}
.excel-namebox {
    padding: 4px 8px;
    border-right: 1px solid #d4d4d4;
    min-width: 60px;
    font-weight: 600;
}
.excel-fx { padding: 4px 8px; border-right: 1px solid #d4d4d4; color: var(--text-lighter); }
.excel-input { padding: 4px 8px; flex: 1; }
.excel-grid { width: 100%; border-collapse: collapse; }
.excel-grid th, .excel-grid td {
    border: 1px solid #e0e0e0;
    padding: 4px 12px;
    text-align: center;
    font-size: 0.75rem;
}
.excel-grid th { background: #f8f8f8; color: var(--text-light); font-weight: 400; }
.excel-grid .row-header { background: #f8f8f8; color: var(--text-light); font-weight: 400; width: 35px; }
.excel-grid .active-cell { background: #e8f4fd; border: 2px solid var(--primary) !important; }
.excel-sheet-tabs {
    display: flex;
    padding: 4px 12px;
    gap: 4px;
    border-top: 1px solid #d4d4d4;
    font-size: 0.7rem;
}
.excel-sheet-tabs span {
    padding: 3px 10px;
    border: 1px solid #d4d4d4;
    background: var(--white);
    border-radius: 0 0 4px 4px;
    border-top: 2px solid transparent;
}
.excel-sheet-tabs span.est-active { border-top-color: var(--green); background: var(--white); font-weight: 600; }
.excel-statusbar {
    background: #217346;
    color: var(--white);
    padding: 3px 12px;
    font-size: 0.7rem;
}

/* ---------- 快捷键表格 ---------- */
.shortcut-table { width: 100%; border-collapse: collapse; margin: 10px 0; }
.shortcut-table th {
    background: var(--primary);
    color: var(--white);
    padding: 8px 12px;
    font-size: 0.85rem;
    text-align: left;
}
.shortcut-table td {
    padding: 8px 12px;
    font-size: 0.85rem;
    border-bottom: 1px solid var(--border);
}
.shortcut-table tr:nth-child(even) { background: #f8fafc; }
.kbd {
    display: inline-block;
    background: #f4f4f4;
    border: 1px solid #d4d4d4;
    border-radius: 4px;
    padding: 1px 6px;
    font-size: 0.8rem;
    font-family: monospace;
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

/* ---------- 测试区 ---------- */
.quiz-container { margin-top: 16px; }
.quiz-question {
    background: var(--white);
    padding: 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
    box-shadow: var(--shadow-sm);
    border-left: 3px solid var(--primary);
}
.quiz-question.correct { border-left-color: var(--green); background: var(--green-bg); }
.quiz-question.wrong { border-left-color: var(--coral); background: var(--coral-bg); }
.quiz-q-text { font-weight: 600; margin-bottom: 10px; font-size: 0.9rem; }
.quiz-options label {
    display: block;
    padding: 8px 12px;
    margin: 4px 0;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: var(--transition);
    border: 1px solid transparent;
}
.quiz-options label:hover { background: var(--bg); }
.quiz-options input[type="radio"] { margin-right: 8px; }
.quiz-options label.opt-correct { background: var(--green-bg); border-color: var(--green); color: var(--green); font-weight: 600; }
.quiz-options label.opt-wrong { background: var(--coral-bg); border-color: var(--coral); color: var(--coral); }
.quiz-explain {
    margin-top: 8px;
    padding: 8px 12px;
    background: var(--blue-bg);
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--blue);
    display: none;
}
.quiz-result {
    text-align: center;
    padding: 20px;
    background: var(--white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    margin-top: 16px;
}
.quiz-score { font-size: 2rem; font-weight: 800; }
.quiz-msg { font-size: 1.1rem; margin: 8px 0; }
.quiz-actions { margin-top: 12px; display: flex; gap: 10px; justify-content: center; }

/* ---------- 数据预览表 ---------- */
.data-preview {
    width: 100%;
    border-collapse: collapse;
    margin: 12px 0;
    font-size: 0.8rem;
}
.data-preview th {
    background: var(--green);
    color: var(--white);
    padding: 8px;
    white-space: nowrap;
}
.data-preview td {
    padding: 6px 8px;
    border-bottom: 1px solid var(--border);
    white-space: nowrap;
}
.data-preview tr:nth-child(even) { background: #f8fafc; }
.data-preview-wrap { overflow-x: auto; margin: 12px 0; }
.data-more { text-align: center; color: var(--text-lighter); font-size: 0.8rem; padding: 8px; }

/* ---------- 步骤列表 ---------- */
.step-list { counter-reset: step; padding-left: 0; }
.step-item {
    display: flex;
    gap: 14px;
    margin-bottom: 12px;
    align-items: flex-start;
}
.step-item::before {
    counter-increment: step;
    content: counter(step);
    background: var(--green);
    color: var(--white);
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
    flex-shrink: 0;
    margin-top: 2px;
}
.step-content { flex: 1; font-size: 0.9rem; color: var(--text-light); }
.step-content strong { color: var(--text); }

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 1024px) {
    .modules-grid { grid-template-columns: repeat(2, 1fr); }
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .concept-cards { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
    .menu-toggle { display: block; }
    .nav-links {
        display: none;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 16px;
        box-shadow: var(--shadow-md);
        gap: 4px;
    }
    .nav-links.show { display: flex; }
    .nav-links a { padding: 12px 16px; }

    .hero { padding: 50px 0 80px; }
    .hero h1 { font-size: 1.8rem; }
    .hero-desc { font-size: 0.95rem; }
    .hero-stats { gap: 30px; }
    .stat-num { font-size: 1.5rem; }

    .modules-grid { grid-template-columns: 1fr; }
    .features-grid { grid-template-columns: 1fr; }

    .section { padding: 40px 0; }
    .section-title { font-size: 1.5rem; }

    .module-hero h1 { font-size: 1.6rem; }
    .lesson-header h3 { font-size: 0.95rem; }
    .lesson-body-inner { padding: 0 16px 20px; }
    .content-block { padding: 14px; }

    .concept-cards { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .hero h1 { font-size: 1.5rem; }
    .hero-stats { flex-direction: column; gap: 12px; }
    .module-card { padding: 20px 16px; }
    .path-container::before { left: 16px; }
    .path-dot { width: 34px; height: 34px; }
}