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

body {
    font-family: 'Helvetica Neue', Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f9f9f9;
}

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

a {
    text-decoration: none;
    color: #333;
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

.section-title {
    text-align: center;
    margin-bottom: 40px;
    font-size: 2.2rem;
    color: #333;
    position: relative;
    padding-bottom: 15px;
}

.section-title:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: #3498db;
}

section {
    padding: 80px 0;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 30px;
    font-weight: bold;
    text-align: center;
    transition: all 0.3s ease;
    margin-right: 15px;
    cursor: pointer;
}

.btn-primary {
    background-color: #3498db;
    color: white;
    border: 2px solid #3498db;
}

.btn-primary:hover {
    background-color: #2980b9;
    border-color: #2980b9;
}

.btn-secondary {
    background-color: transparent;
    color: #3498db;
    border: 2px solid #3498db;
}

.btn-secondary:hover {
    background-color: #3498db;
    color: white;
}

/* 头部导航 */
header {
    background-color: white;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 1000;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo h1 {
    font-size: 1.8rem;
    color: #3498db;
    font-weight: bold;
}

nav ul {
    display: flex;
}

nav ul li {
    margin-left: 30px;
}

nav ul li a {
    font-weight: 500;
    position: relative;
    padding-bottom: 5px;
}

nav ul li a:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: #3498db;
    transition: width 0.3s ease;
}

nav ul li a:hover:after {
    width: 100%;
}

/* 英雄区域 */
.hero {
    padding-top: 150px;
    background: linear-gradient(135deg, #f0f8ff 0%, #e1f0fa 100%);
}

.hero .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.hero-content {
    flex: 1;
    padding-right: 50px;
}

.hero-image {
    flex: 1;
    text-align: center;
    display: flex;
    justify-content: center;
    align-items: center;
}

.artistic-hero {
    position: relative;
    width: 400px;
    height: 400px;
    background: linear-gradient(135deg, #e1f0fa 0%, #f0f8ff 100%);
    border-radius: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: 0 10px 30px rgba(52, 152, 219, 0.2);
    overflow: hidden;
}

.artistic-hero:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%233498db' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.8;
}

.math-symbol {
    position: absolute;
    font-size: 80px;
    font-weight: bold;
    color: rgba(52, 152, 219, 0.7);
    animation: float 6s infinite ease-in-out;
    text-shadow: 0 2px 10px rgba(52, 152, 219, 0.3);
}

.math-small {
    font-size: 40px;
    opacity: 0.6;
}

.math-formula {
    position: absolute;
    font-family: 'Times New Roman', serif;
    font-style: italic;
    font-size: 20px;
    color: rgba(52, 152, 219, 0.8);
    background: rgba(255, 255, 255, 0.7);
    padding: 5px 12px;
    border-radius: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    animation: rotate-slow 20s infinite linear;
    transform-origin: center center;
}

.math-formula:nth-of-type(1) {
    top: 70px;
    right: 70px;
    animation-duration: 25s;
}

.math-formula:nth-of-type(2) {
    bottom: 80px;
    left: 50px;
    animation-duration: 30s;
    animation-direction: reverse;
}

@keyframes rotate-slow {
    0% {
        transform: rotate(0deg) translateX(30px) rotate(0deg);
    }
    100% {
        transform: rotate(360deg) translateX(30px) rotate(-360deg);
    }
}

.math-symbol:nth-child(1) {
    top: 60px;
    left: 60px;
    animation-delay: 0s;
}

.math-symbol:nth-child(2) {
    top: 180px;
    right: 70px;
    animation-delay: 1s;
}

.math-symbol:nth-child(3) {
    bottom: 70px;
    left: 100px;
    animation-delay: 2s;
}

.math-symbol:nth-child(4) {
    bottom: 120px;
    right: 100px;
    animation-delay: 3s;
}

.math-symbol:nth-child(5) {
    top: 100px;
    left: 160px;
    animation-delay: 1.5s;
}

.math-symbol:nth-child(6) {
    top: 240px;
    left: 220px;
    animation-delay: 2.5s;
}

.math-symbol:nth-child(7) {
    bottom: 150px;
    right: 180px;
    animation-delay: 3.5s;
}

.math-circle, .math-square, .math-triangle {
    position: absolute;
    opacity: 0.2;
    animation: rotate 20s infinite linear;
}

.math-circle {
    width: 100px;
    height: 100px;
    border: 10px solid #3498db;
    border-radius: 50%;
    top: 50px;
    right: 50px;
}

.math-square {
    width: 80px;
    height: 80px;
    border: 10px solid #3498db;
    bottom: 60px;
    left: 60px;
    animation-direction: reverse;
}

.math-triangle {
    width: 0;
    height: 0;
    border-left: 60px solid transparent;
    border-right: 60px solid transparent;
    border-bottom: 100px solid rgba(52, 152, 219, 0.3);
    top: 150px;
    left: 150px;
    animation-duration: 15s;
}

/* Add mathematical formulas as pseudo-elements */
.artistic-hero:after {
    content: 'x² + y² = r²';
    position: absolute;
    bottom: 30px;
    right: 40px;
    font-family: 'Times New Roman', serif;
    font-style: italic;
    font-size: 24px;
    color: rgba(52, 152, 219, 0.6);
    transform: rotate(-10deg);
    animation: pulse 4s infinite ease-in-out;
}

@keyframes pulse {
    0%, 100% {
        opacity: 0.6;
    }
    50% {
        opacity: 0.9;
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) scale(1);
    }
    50% {
        transform: translateY(-20px) scale(1.05);
    }
}

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

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 15px;
    color: #333;
}

.hero h2 {
    font-size: 1.8rem;
    margin-bottom: 15px;
    color: #3498db;
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    color: #666;
}

.cta-buttons {
    margin-top: 30px;
}

/* 特点部分 */
.features {
    background-color: white;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
}

@media (max-width: 1200px) {
    .features-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 900px) {
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 600px) {
    .features-grid {
        grid-template-columns: 1fr;
    }
}

.feature-item {
    text-align: center;
    padding: 25px 20px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border-top: 3px solid #3498db;
    background-color: #fff;
}

.feature-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(52, 152, 219, 0.2);
}

.feature-icon {
    font-size: 2rem;
    color: #fff;
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #3498db, #2980b9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.2);
}

.feature-item h3 {
    margin-bottom: 15px;
    font-size: 1.3rem;
}

/* 教师部分 */
.teachers {
    background-color: #f9f9f9;
}

.teachers-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.teacher-card {
    background-color: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease;
}

.teacher-card:hover {
    transform: translateY(-10px);
}

.teacher-image {
    height: 250px;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, #f0f8ff 0%, #e1f0fa 100%);
}

.teacher-avatar {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    background: linear-gradient(45deg, #3498db, #5dade2);
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: 0 10px 20px rgba(255, 126, 0, 0.3);
    transition: transform 0.5s ease, box-shadow 0.5s ease;
    position: relative;
    overflow: hidden;
}

.teacher-avatar:before {
    content: '';
    position: absolute;
    top: -20px;
    left: -20px;
    right: -20px;
    bottom: -20px;
    background: linear-gradient(45deg, rgba(255, 255, 255, 0.2), transparent);
    transform: rotate(45deg);
}

.teacher-avatar-text {
    font-size: 80px;
    font-weight: bold;
    color: white;
    text-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.teacher-card:hover .teacher-avatar {
    transform: scale(1.05);
    box-shadow: 0 15px 30px rgba(255, 126, 0, 0.4);
}

.teacher-card h3 {
    padding: 20px 20px 5px;
    font-size: 1.4rem;
}

.teacher-title {
    padding: 0 20px 10px;
    color: #3498db;
    font-weight: bold;
}

.teacher-desc {
    padding: 0 20px 20px;
    color: #666;
}

/* 课程部分 */
.courses {
    background-color: white;
}

.course-preview {
    display: flex;
    align-items: center;
    background-color: #f9f9f9;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.05);
}

.video-container {
    flex: 1;
    padding: 20px;
}

.video-placeholder {
    width: 100%;
    height: 300px;
    background: linear-gradient(135deg, #3498db, #5dade2);
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    overflow: hidden;
    box-shadow: 0 10px 20px rgba(52, 152, 219, 0.2);
    cursor: pointer;
    transition: transform 0.3s ease;
}

.video-placeholder:hover {
    transform: scale(1.02);
}

.video-placeholder:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("data:image/svg+xml,%3Csvg width='100' height='100' viewBox='0 0 100 100' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M11 18c3.866 0 7-3.134 7-7s-3.134-7-7-7-7 3.134-7 7 3.134 7 7 7zm48 25c3.866 0 7-3.134 7-7s-3.134-7-7-7-7 3.134-7 7 3.134 7 7 7zm-43-7c1.657 0 3-1.343 3-3s-1.343-3-3-3-3 1.343-3 3 1.343 3 3 3zm63 31c1.657 0 3-1.343 3-3s-1.343-3-3-3-3 1.343-3 3 1.343 3 3 3zM34 90c1.657 0 3-1.343 3-3s-1.343-3-3-3-3 1.343-3 3 1.343 3 3 3zm56-76c1.657 0 3-1.343 3-3s-1.343-3-3-3-3 1.343-3 3 1.343 3 3 3zM12 86c2.21 0 4-1.79 4-4s-1.79-4-4-4-4 1.79-4 4 1.79 4 4 4zm28-65c2.21 0 4-1.79 4-4s-1.79-4-4-4-4 1.79-4 4 1.79 4 4 4zm23-11c2.76 0 5-2.24 5-5s-2.24-5-5-5-5 2.24-5 5 2.24 5 5 5zm-6 60c2.21 0 4-1.79 4-4s-1.79-4-4-4-4 1.79-4 4 1.79 4 4 4zm29 22c2.76 0 5-2.24 5-5s-2.24-5-5-5-5 2.24-5 5 2.24 5 5 5zM32 63c2.76 0 5-2.24 5-5s-2.24-5-5-5-5 2.24-5 5 2.24 5 5 5zm57-13c2.76 0 5-2.24 5-5s-2.24-5-5-5-5 2.24-5 5 2.24 5 5 5zm-9-21c1.105 0 2-.895 2-2s-.895-2-2-2-2 .895-2 2 .895 2 2 2zM60 91c1.105 0 2-.895 2-2s-.895-2-2-2-2 .895-2 2 .895 2 2 2zM35 41c1.105 0 2-.895 2-2s-.895-2-2-2-2 .895-2 2 .895 2 2 2zM12 60c1.105 0 2-.895 2-2s-.895-2-2-2-2 .895-2 2 .895 2 2 2z' fill='%23ffffff' fill-opacity='0.1' fill-rule='evenodd'/%3E%3C/svg%3E");
    opacity: 0.5;
}

.video-placeholder:after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.3;
}

.play-button {
    width: 80px;
    height: 80px;
    background-color: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 20px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, background-color 0.3s ease;
}

.video-placeholder:hover .play-button {
    transform: scale(1.1);
    background-color: white;
}

.play-button i {
    color: #3498db;
    font-size: 30px;
    margin-left: 8px; /* Offset to center the play icon visually */
}

.video-text {
    text-align: center;
    color: white;
    font-weight: bold;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.video-text p:first-child {
    font-size: 1.4rem;
    margin-bottom: 5px;
}

.video-text p:last-child {
    font-size: 1rem;
    opacity: 0.9;
}

.course-video {
    width: 100%;
    height: 300px;
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(52, 152, 219, 0.2);
    background-color: #000;
}

.course-info {
    flex: 1;
    padding: 40px;
}

.course-info h3 {
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.course-teacher {
    color: #3498db;
    font-weight: bold;
    margin-bottom: 15px;
}

.course-desc {
    margin-bottom: 20px;
    color: #666;
}

.course-features {
    display: flex;
    flex-wrap: wrap;
}

.course-features span {
    margin-right: 20px;
    color: #666;
}

.course-features i {
    color: #3498db;
    margin-right: 5px;
}

/* 二维码部分 */
.qrcode-section {
    background: linear-gradient(135deg, #f0f8ff 0%, #e1f0fa 100%);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.qrcode-section:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%233498db' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.5;
    z-index: 0;
}

.qrcode-content {
    margin-bottom: 40px;
}

.qrcode-content h2 {
    font-size: 2rem;
    margin-bottom: 15px;
}

.qrcode-content p {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 30px;
}

.qrcode-img-container {
    width: 200px;
    height: 220px;
    background: #fff;
    border-radius: 10px;
    margin: 0 auto 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.2);
    overflow: hidden;
    padding: 15px;
}

.qrcode-img {
    width: 180px;
    height: 180px;
    object-fit: contain;
    margin-bottom: 10px;
}

.qrcode-flex {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.qrcode-info {
    max-width: 400px;
    text-align: left;
}

.qrcode-info h3 {
    font-size: 24px;
    margin-bottom: 15px;
    color: #3498db;
}

.qrcode-info p {
    margin-bottom: 25px;
    color: #666;
    line-height: 1.6;
}



.qrcode-text {
    color: #3498db;
    font-weight: bold;
    font-size: 1rem;
    margin-top: 5px;
}

.qrcode-tip {
    font-size: 1rem;
    color: #888;
}

/* 关于部分 */
.about {
    background-color: white;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-content p {
    margin-bottom: 20px;
    font-size: 1.1rem;
    color: #666;
}

/* 页脚 */
footer {
    background-color: #333;
    text-align: center;
    padding: 15px 0;
}

.copyright {
    color: #ccc;
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 992px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .teachers-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .course-preview {
        flex-direction: column;
    }
    
    /* Footer responsive styles removed as footer is now simplified */
}

@media (max-width: 768px) {
    .hero .container {
        flex-direction: column;
        text-align: center;
    }
    
    .hero-content {
        padding-right: 0;
        margin-bottom: 40px;
    }
    
    header .container {
        flex-direction: column;
    }
    
    nav ul {
        margin-top: 15px;
    }
    
    nav ul li {
        margin: 0 15px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .teachers-grid {
        grid-template-columns: 1fr;
    }
}