/* css/style.css - 主页面样式 - 多背景图片主题 */

/* 字体定义 */
@font-face {
    font-family: 'MyCustomFont';
    src: url('../font/13.woff2') format('woff2');
    font-weight: normal;
    font-style: normal;
    font-display: swap; /* 确保文本不会因为字体加载而闪烁 */
}

/* 基础样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 蓝色系 */
    --blue-primary: #4A90E2;
    --blue-light: #6BB0FF;
    --blue-lighter: #8CC2FF;
    --blue-pastel: #E6F2FF;
    --blue-soft: #F0F8FF;
    --blue-dark: #3A7BC8;
    
    /* 粉色系 */
    --pink-primary: #FF6B93;
    --pink-light: #FF9EBB;
    --pink-lighter: #FFC8DD;
    --pink-pastel: #FFE4EC;
    --pink-soft: #FFF0F5;
    
    /* 中性色 - 白色系 */
    --white-dark: #F5F5F5;
    --white-medium: #FAFAFA;
    --white-light: #FFFFFF;
    --white-cream: #FFFEFC;
    
    /* 文字颜色 */
    --text-dark: #5A4B4B;
    --text-medium: #7A6B6B;
    --text-light: #9A8B8B;
    --text-white: #FFFFFF;
    
    /* 渐变 */
    --gradient-blue-pink: linear-gradient(135deg, var(--blue-primary) 0%, var(--pink-primary) 100%);
    --gradient-pink-blue: linear-gradient(135deg, var(--pink-primary) 0%, var(--blue-primary) 100%);
    --gradient-blue: linear-gradient(135deg, var(--blue-light) 0%, var(--blue-primary) 50%, var(--blue-dark) 100%);
    --gradient-pink: linear-gradient(135deg, var(--pink-light) 0%, var(--pink-primary) 50%, #FF4081 100%);
    --gradient-white: linear-gradient(135deg, var(--white-medium) 0%, var(--white-light) 50%, var(--white-cream) 100%);
    
    /* 阴影 */
    --shadow-light: rgba(74, 144, 226, 0.08);
    --shadow-medium: rgba(74, 144, 226, 0.12);
    --shadow-dark: rgba(74, 144, 226, 0.16);
    --shadow-pink: rgba(255, 107, 147, 0.12);
    --shadow-white: rgba(255, 255, 255, 0.15);
}

body {
    font-family: 'MyCustomFont', 'Nunito', 'Poppins', sans-serif;
    background: 
        /* 减少透明度，让girl.jpg更清晰 */
        linear-gradient(rgba(255, 255, 255, 0.4), rgba(255, 255, 255, 0.5)),
        url('../package/girl.jpg') no-repeat center center fixed;
    background-size: cover;
    color: var(--text-dark);
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

/* 装饰元素 */
.floating-elements {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.floating-element {
    position: absolute;
    font-size: 2rem;
    opacity: 0.15;
    animation: float 25s infinite linear;
}

.floating-element.element1 {
    top: 15%;
    left: 8%;
    color: var(--blue-primary);
    animation-delay: 0s;
}

.floating-element.element2 {
    top: 35%;
    right: 12%;
    color: var(--pink-primary);
    animation-delay: 8s;
}

.floating-element.element3 {
    bottom: 25%;
    left: 20%;
    color: var(--pink-lighter);
    animation-delay: 16s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    25% {
        transform: translateY(-25px) rotate(90deg);
    }
    50% {
        transform: translateY(0) rotate(180deg);
    }
    75% {
        transform: translateY(25px) rotate(270deg);
    }
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 25px 20px;
    position: relative;
    z-index: 1;
}

/* 头部样式 - 使用girl2.jpg背景 */
.main-header {
    text-align: center;
    margin-bottom: 60px;
    padding-top: 30px;
    background: 
        linear-gradient(rgba(255, 255, 255, 0.4), rgba(255, 255, 255, 0.5)),
        url('../package/girl2.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 25px;
    padding: 35px;
    box-shadow: 0 10px 30px var(--shadow-light);
    backdrop-filter: blur(2px);
    border: 3px solid rgba(255, 255, 255, 0.8);
    position: relative;
    overflow: hidden;
}

/* 头部装饰边框 */
.main-header::before {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-white);
    border-radius: 28px;
    z-index: -1;
    animation: borderGlow 3s ease-in-out infinite alternate;
}

.logo-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
    position: relative;
    z-index: 2;
}

.logo-icon {
    width: 85px;
    height: 85px;
    background: var(--gradient-blue-pink);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.8rem;
    color: white;
    box-shadow: 0 12px 30px var(--shadow-medium);
    margin-bottom: 15px;
    border: 3px solid var(--white-light);
    position: relative;
    z-index: 1;
}

.logo-text h1 {
    font-size: 2.8rem;
    color: var(--text-dark);
    margin-bottom: 10px;
    font-weight: 700;
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    position: relative;
}

.tagline {
    font-size: 1.3rem;
    color: var(--text-medium);
    font-weight: 400;
    line-height: 1.5;
}

.header-subtitle {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    padding: 14px 30px;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 50px;
    font-size: 1.2rem;
    color: var(--blue-primary);
    box-shadow: 0 8px 25px var(--shadow-light);
    border: 2px solid var(--white-light);
    margin-top: 15px;
    position: relative;
    z-index: 2;
}

.header-subtitle i {
    font-size: 1.3rem;
    color: var(--pink-primary);
}

/* 七年级部分 - 使用girl4.jpg背景，去除蓝色边框 */
.grade-7 {
    position: relative;
    margin-bottom: 70px;
    background: 
        linear-gradient(rgba(255, 255, 255, 0.4), rgba(255, 255, 255, 0.5)),
        url('../package/girl4.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 25px;
    padding: 30px;
    box-shadow: 0 15px 35px var(--shadow-light);
    backdrop-filter: blur(2px);
    border: 3px solid rgba(255, 255, 255, 0.8);
    overflow: hidden;
}

/* 七年级装饰边框 - 移除蓝色边框 */
.grade-7::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: transparent; /* 移除蓝色渐变背景 */
    border-radius: 25px;
    z-index: -1;
    opacity: 0;
}

.grade-7::after {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: transparent; /* 移除蓝色装饰边框 */
    border-radius: 28px;
    z-index: -2;
    animation: none; /* 移除动画 */
}

/* 八年级部分 - 粉色背景 */
.grade-8 {
    position: relative;
    margin-bottom: 70px;
    background: 
        linear-gradient(rgba(255, 107, 147, 0.05), rgba(255, 107, 147, 0.08)),
        url('../package/girl3.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 25px;
    padding: 30px;
    box-shadow: 0 15px 35px var(--shadow-pink);
    backdrop-filter: blur(5px);
    border: 3px solid transparent;
    overflow: hidden;
}

/* 八年级装饰边框 */
.grade-8::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-pink);
    border-radius: 25px;
    z-index: -1;
    opacity: 0.1;
}

.grade-8::after {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-pink);
    border-radius: 28px;
    z-index: -2;
    animation: borderGlowPink 3s ease-in-out infinite alternate;
}

@keyframes borderGlowPink {
    0% {
        opacity: 0.3;
    }
    100% {
        opacity: 0.6;
    }
}

/* 年级内部容器 */
.section-header {
    position: relative; /* 添加相对定位 */
    margin-bottom: 40px;
    padding: 25px;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.05);
    border: 2px solid;
    z-index: 1;
}

/* 七年级头部边框改为透明 */
.grade7-header {
    border-color: transparent;
    background: 
        /* 添加女孩图片背景 */
        linear-gradient(rgba(255, 255, 255, 0.4), rgba(255, 255, 255, 0.5)),
        url('../package/girl4.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 20px;
    position: relative;
    overflow: hidden;
}

/* 添加遮罩层，让文字更清晰 */
.grade7-header::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.6);
    border-radius: 20px;
    z-index: 0;
}

/* 确保内容在遮罩层之上 */
.grade7-header .grade-icon,
.grade7-header .grade-info {
    position: relative;
    z-index: 1;
}

.grade8-header {
    border-color: var(--pink-primary);
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(255, 240, 245, 0.95));
}

.grade-icon {
    width: 75px;
    height: 75px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.2rem;
    flex-shrink: 0;
}

.grade7-header .grade-icon {
    background: var(--gradient-blue);
    color: white;
    box-shadow: 0 8px 20px rgba(74, 144, 226, 0.3);
}

.grade8-header .grade-icon {
    background: var(--gradient-pink);
    color: white;
    box-shadow: 0 8px 20px rgba(255, 107, 147, 0.3);
}

.grade-info h2 {
    font-size: 1.9rem;
    color: var(--text-dark);
    margin-bottom: 8px;
    font-weight: 700;
    padding-left: 0; /* 移除左边距 */
}

.grade-info {
    padding-top: 15px; /* 给图标留出空间 */
}

.grade7-header .grade-info h2 {
    color: var(--text-dark); /* 改为深色文字 */
}

.grade8-header .grade-info h2 {
    background: var(--gradient-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.grade-info p {
    color: var(--text-medium);
    font-size: 1.15rem;
    line-height: 1.6;
}

/* 知识点网格 */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 30px;
    position: relative;
    z-index: 1;
}

.topic-card {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    padding: 30px;
    text-decoration: none;
    color: inherit;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: 0 10px 30px var(--shadow-light);
    border: 3px solid;
    display: flex;
    flex-direction: column;
    height: 100%;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(5px);
}

/* 七年级知识点边框 - 改为半透明边框 */
.grade-7 .topic-card {
    border-color: rgba(255, 255, 255, 0.8); /* 改为半透明边框 */
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(240, 248, 255, 0.95));
}

.grade-7 .topic-card:hover {
    border-color: rgba(255, 255, 255, 0.9); /* 悬停时边框 */
    background: linear-gradient(rgba(255, 255, 255, 0.98), rgba(255, 255, 255, 0.98));
}

/* 八年级知识点边框 */
.grade-8 .topic-card {
    border-color: var(--pink-light);
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(255, 240, 245, 0.95));
}

.grade-8 .topic-card:hover {
    border-color: var(--pink-primary);
    background: linear-gradient(rgba(255, 255, 255, 0.98), rgba(255, 255, 255, 0.98));
}

.topic-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 5px;
}

/* 七年级知识点顶部装饰 - 改为半透明 */
.grade-7 .topic-card::before {
    background: rgba(255, 255, 255, 0.8); /* 改为半透明装饰线 */
}

/* 八年级知识点顶部装饰 */
.grade-8 .topic-card::before {
    background: var(--gradient-pink);
}

.topic-card:hover {
    transform: translateY(-12px) scale(1.02);
    box-shadow: 0 25px 50px var(--shadow-dark);
}

.topic-card:hover::before {
    height: 6px;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
}

.topic-icon {
    width: 65px;
    height: 65px;
    border-radius: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.9rem;
}

/* 七年级知识点图标颜色 */
.grade-7 .topic-card .topic-icon {
    background: linear-gradient(135deg, rgba(74, 144, 226, 0.15) 0%, rgba(74, 144, 226, 0.25) 100%);
    color: var(--blue-primary);
}

/* 八年级知识点图标颜色 */
.grade-8 .topic-card .topic-icon {
    background: linear-gradient(135deg, rgba(255, 107, 147, 0.15) 0%, rgba(255, 107, 147, 0.25) 100%);
    color: var(--pink-primary);
}

.topic-number {
    font-size: 1.6rem;
    font-weight: 700;
    opacity: 0.3;
}

/* 七年级知识点数字颜色 */
.grade-7 .topic-card .topic-number {
    color: var(--blue-primary);
}

/* 八年级知识点数字颜色 */
.grade-8 .topic-card .topic-number {
    color: var(--pink-primary);
}

.card-body h3 {
    font-size: 1.7rem;
    color: var(--text-dark);
    margin-bottom: 15px;
    font-weight: 700;
}

.card-body p {
    color: var(--text-medium);
    line-height: 1.6;
    margin-bottom: 30px;
    flex-grow: 1;
    font-size: 1.05rem;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 25px;
    border-top: 1px solid rgba(74, 144, 226, 0.1);
}

.grade-tag {
    padding: 8px 18px;
    border-radius: 25px;
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

/* 七年级标签颜色 */
.grade-7 .topic-card .grade-tag {
    background: linear-gradient(135deg, rgba(74, 144, 226, 0.15) 0%, rgba(74, 144, 226, 0.25) 100%);
    color: var(--blue-primary);
    border: 1px solid rgba(74, 144, 226, 0.3);
}

/* 八年级标签颜色 */
.grade-8 .topic-card .grade-tag {
    background: linear-gradient(135deg, rgba(255, 107, 147, 0.15) 0%, rgba(255, 107, 147, 0.25) 100%);
    color: var(--pink-primary);
    border: 1px solid rgba(255, 107, 147, 0.3);
}

.learn-link {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    transition: gap 0.3s;
}

/* 七年级学习链接颜色 */
.grade-7 .topic-card .learn-link {
    color: var(--blue-primary);
}

/* 八年级学习链接颜色 */
.grade-8 .topic-card .learn-link {
    color: var(--pink-primary);
}

.topic-card:hover .learn-link {
    gap: 15px;
}

/* 特色部分 - 渐变背景 */
.features-section {
    position: relative;
    margin: 80px 0 70px;
    background: 
        linear-gradient(rgba(74, 144, 226, 0.05), rgba(255, 107, 147, 0.05)),
        url('../package/girl5.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 25px;
    padding: 40px;
    box-shadow: 0 15px 35px var(--shadow-light);
    backdrop-filter: blur(5px);
    border: 3px solid transparent;
    overflow: hidden;
}

/* 特色部分装饰边框 */
.features-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-blue-pink);
    border-radius: 25px;
    z-index: -1;
    opacity: 0.1;
}

.features-section::after {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-blue-pink);
    border-radius: 28px;
    z-index: -2;
    animation: borderGlowGradient 3s ease-in-out infinite alternate;
}

@keyframes borderGlowGradient {
    0% {
        opacity: 0.3;
    }
    100% {
        opacity: 0.6;
    }
}

@keyframes borderGlow {
    0% {
        opacity: 0.3;
    }
    100% {
        opacity: 0.6;
    }
}

.features-title {
    text-align: center;
    font-size: 2.3rem;
    color: var(--text-dark);
    margin-bottom: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    font-weight: 700;
    position: relative;
    z-index: 1;
}

.features-title i {
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 2.5rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 35px;
    position: relative;
    z-index: 1;
}

.feature-card {
    background: rgba(255, 255, 255, 0.95);
    padding: 35px;
    border-radius: 22px;
    text-align: center;
    box-shadow: 0 12px 35px var(--shadow-medium);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    border: 3px solid;
    position: relative;
    backdrop-filter: blur(5px);
}

.feature-card:nth-child(1) {
    border-color: var(--blue-primary);
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(240, 248, 255, 0.95));
}

.feature-card:nth-child(2) {
    border-color: var(--pink-primary);
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(255, 240, 245, 0.95));
}

.feature-card:nth-child(3) {
    border-color: transparent;
    border-image: var(--gradient-blue-pink);
    border-image-slice: 1;
    background: linear-gradient(rgba(255, 255, 255, 0.95), rgba(255, 255, 255, 0.95));
}

.feature-card:hover {
    transform: translateY(-15px);
    box-shadow: 0 25px 50px var(--shadow-dark);
    background: rgba(255, 255, 255, 0.98);
}

.feature-icon {
    width: 90px;
    height: 90px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 25px;
    font-size: 2.3rem;
    color: white;
    background: var(--gradient-blue-pink);
    box-shadow: 0 12px 25px rgba(74, 144, 226, 0.3);
}

.feature-card:nth-child(1) .feature-icon {
    background: var(--gradient-blue);
}

.feature-card:nth-child(2) .feature-icon {
    background: var(--gradient-pink);
}

.feature-card:nth-child(3) .feature-icon {
    background: var(--gradient-blue-pink);
}

.feature-card h3 {
    font-size: 1.6rem;
    color: var(--text-dark);
    margin-bottom: 20px;
    font-weight: 700;
}

.feature-card p {
    color: var(--text-medium);
    line-height: 1.7;
    font-size: 1.05rem;
}

/* 页脚 - 渐变背景 */
.main-footer {
    position: relative;
    margin-top: 80px;
    padding: 50px 0;
    text-align: center;
    background: 
        linear-gradient(rgba(74, 144, 226, 0.05), rgba(255, 107, 147, 0.05)),
        url('../package/girl3.jpg') no-repeat center center;
    background-size: cover;
    border-radius: 25px;
    box-shadow: 0 15px 35px var(--shadow-light);
    backdrop-filter: blur(5px);
    border: 3px solid transparent;
    overflow: hidden;
}

/* 页脚装饰边框 */
.main-footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-blue-pink);
    border-radius: 25px;
    z-index: -1;
    opacity: 0.1;
}

.main-footer::after {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-blue-pink);
    border-radius: 28px;
    z-index: -2;
    animation: borderGlowGradient 3s ease-in-out infinite alternate;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
    position: relative;
    z-index: 1;
}

.footer-logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    font-size: 1.6rem;
    color: var(--text-dark);
    margin-bottom: 25px;
    font-weight: 700;
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-logo i {
    font-size: 1.8rem;
}

.footer-copyright {
    color: var(--text-medium);
    margin-bottom: 15px;
    font-size: 1.05rem;
}

.footer-note {
    color: var(--text-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    font-size: 1.05rem;
}

.footer-note i {
    color: var(--blue-primary);
}

/* 返回顶部按钮样式 */
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 60px;
    height: 60px;
    background: var(--gradient-blue-pink);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.4rem;
    z-index: 1000;
    display: none;
    transition: all 0.3s ease;
    box-shadow: 0 8px 25px rgba(74, 144, 226, 0.3);
    border: 3px solid var(--white-light);
}

.back-to-top:hover {
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 15px 35px rgba(74, 144, 226, 0.4);
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .topics-grid {
        grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
        gap: 25px;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 20px 15px;
    }
    
    .logo-text h1 {
        font-size: 2.2rem;
    }
    
    .tagline {
        font-size: 1.1rem;
    }
    
    .header-subtitle {
        font-size: 1rem;
        padding: 12px 25px;
        flex-direction: column;
        gap: 8px;
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .section-header {
        flex-direction: column;
        text-align: center;
        gap: 20px;
        padding: 20px;
    }
    
    .grade-info h2 {
        font-size: 1.6rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .features-title {
        font-size: 1.9rem;
        flex-direction: column;
        gap: 15px;
    }
    
    .topic-card {
        padding: 25px;
    }
    
    .card-body h3 {
        font-size: 1.5rem;
    }
    
    .back-to-top {
        bottom: 25px;
        right: 25px;
        width: 50px;
        height: 50px;
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .main-header {
        padding: 25px 20px;
    }
    
    .logo-icon {
        width: 70px;
        height: 70px;
        font-size: 2.2rem;
    }
    
    .logo-text h1 {
        font-size: 1.9rem;
    }
    
    .grade-section {
        padding: 20px 15px;
    }
    
    .feature-card {
        padding: 25px 20px;
    }
    
    .feature-icon {
        width: 75px;
        height: 75px;
        font-size: 1.9rem;
    }
}

/* 打印样式 */
@media print {
    .floating-elements,
    .back-to-top {
        display: none;
    }
    
    .topic-card:hover {
        transform: none;
        box-shadow: none;
    }
    
    body {
        background: white !important;
    }
    
    .grade-section,
    .topic-card,
    .feature-card,
    .main-header,
    .main-footer {
        box-shadow: none;
        border: 1px solid #ddd;
        page-break-inside: avoid;
    }
    
    /* 移除背景图片 */
    .main-header,
    .grade-7,
    .grade-8,
    .features-section,
    .main-footer {
        background: white !important;
    }
}