/* 全局样式 */
:root {
    --primary-color: #4285f4;
    --secondary-color: #4e5968;
    --success-color: #34a853;
    --warning-color: #fbbc05;
    --danger-color: #ea4335;
    --dark-color: #333;
    --light-color: #f4f4f4;
    --gray-color: #888;
    --box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--dark-color);
    background-color: #fff;
}

a {
    text-decoration: none;
    color: var(--primary-color);
}

.container {
    max-width: 3200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 标题样式 */
h1, h2, h3 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 15px;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 8px 16px;
    border-radius: 50px;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    font-size: 14px;
    position: relative;
    overflow: hidden;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    opacity: 0.95;
}

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

.btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 5px;
    height: 5px;
    background: rgba(255, 255, 255, 0.5);
    opacity: 0;
    border-radius: 100%;
    transform: scale(1, 1) translate(-50%, -50%);
    transform-origin: 50% 50%;
}

.btn:hover::after {
    animation: ripple 1s ease-out;
}

@keyframes ripple {
    0% {
        transform: scale(0, 0);
        opacity: 0.5;
    }
    100% {
        transform: scale(20, 20);
        opacity: 0;
    }
}

.btn-large {
    padding: 12px 30px;
    font-size: 16px;
}

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

.btn-secondary:hover {
    background: #3c4654;
}

/* 头部样式 */
header {
    background: linear-gradient(135deg, #4285f4, #34a853);
    color: white;
    padding: 120px 0 70px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100"><rect x="0" y="0" width="100" height="100" fill="none"/><path d="M0 0L100 100" stroke="rgba(255,255,255,0.05)" stroke-width="1"/><path d="M100 0L0 100" stroke="rgba(255,255,255,0.05)" stroke-width="1"/></svg>');
    opacity: 0.3;
}

header h1 {
    font-size: 48px;
    margin-bottom: 10px;
    position: relative;
}

header .subtitle {
    font-size: 22px;
    opacity: 0.9;
    margin-bottom: 30px;
}

/* 介绍部分 */
.intro {
    text-align: center;
    padding: 35px 0;
    background-color: #f0f5ff;
    border-bottom: 1px solid #e1e8f5;
    position: relative;
}

.intro::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    background-image: radial-gradient(#4285f4 1px, transparent 1px);
    background-size: 20px 20px;
    opacity: 0.1;
}

.intro h2 {
    font-size: 30px;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.intro p {
    font-size: 16px;
    max-width: 95%;
    margin: 0 auto;
    color: #4a5568;
    line-height: 1.5;
}

/* 步骤部分 */
.steps {
    padding: 70px 0;
}

.step-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.step {
    background: white;
    border-radius: 10px;
    box-shadow: var(--box-shadow);
    overflow: hidden;
    transition: var(--transition);
}

.step:hover {
    transform: translateY(-5px);
}

.step-number {
    background-color: var(--primary-color);
    color: white;
    font-size: 24px;
    font-weight: bold;
    padding: 15px 0;
    text-align: center;
}

.step-content {
    padding: 25px;
}

.step h3 {
    font-size: 22px;
    margin-bottom: 15px;
}

.step p {
    margin-bottom: 20px;
    color: var(--gray-color);
}

.step-links {
    display: flex;
    justify-content: flex-start;
}

/* CTA部分 */
.cta {
    background: linear-gradient(135deg, #4285f4, #34a853);
    color: white;
    text-align: center;
    padding: 60px 0;
    position: relative;
    overflow: hidden;
    margin-top: 50px;
}

.cta::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100"><rect x="0" y="0" width="100" height="100" fill="none"/><path d="M0 0L100 100" stroke="rgba(255,255,255,0.05)" stroke-width="1"/><path d="M100 0L0 100" stroke="rgba(255,255,255,0.05)" stroke-width="1"/></svg>');
    opacity: 0.3;
}

.cta h2 {
    font-size: 36px;
    margin-bottom: 20px;
}

.cta p {
    font-size: 18px;
    max-width: 600px;
    margin: 0 auto 30px;
    opacity: 0.9;
}

/* 页脚样式 */
footer {
    padding: 20px 0;
    text-align: center;
    background-color: #f8f9fa;
    border-top: 1px solid #eaeaea;
}

footer a {
    color: var(--primary-color);
    font-weight: bold;
    transition: var(--transition);
}

footer a:hover {
    text-decoration: underline;
    color: #0051b3;
}

/* 主内容三列布局 */
.main-content {
    padding: 40px 0 60px;
    background-color: #f9fafb;
}

.three-column-layout {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 25px;
    max-width: 95%;
    margin: 0 auto;
    padding: 0 15px;
}

.column {
    display: flex;
    flex-direction: column;
    background: white;
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.05);
    position: relative;
    overflow: hidden;
}

.column::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(90deg, var(--primary-color), rgba(66, 133, 244, 0.6));
}

.column h2 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 24px;
    position: relative;
    padding-bottom: 10px;
    font-weight: 700;
}

.column h2::after {
    content: '';
    position: absolute;
    width: 45px;
    height: 3px;
    background: var(--primary-color);
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    border-radius: 2px;
}

/* 左侧步骤样式 */
.left-steps .step {
    background: white;
    border-radius: 10px;
    box-shadow: var(--box-shadow);
    overflow: hidden;
    transition: var(--transition);
    height: 100%;
    width: 100%;
    display: flex;
    flex-direction: column;
    min-height: 280px;
}

.left-steps .step:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 30px rgba(66, 133, 244, 0.1);
}

.left-steps .step-number {
    padding: 8px 0;
    font-size: 20px;
}

.left-steps .step-content {
    padding: 15px;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.left-steps h3 {
    font-size: 16px;
    margin-bottom: 10px;
}

.left-steps p {
    font-size: 13px;
    margin-bottom: 15px;
    color: var(--gray-color);
    line-height: 1.5;
    flex: 1;
    display: flex;
    align-items: center;
    overflow-wrap: break-word;
    word-wrap: break-word;
    hyphens: auto;
    max-height: 100px;
    overflow-y: auto;
}

.left-steps .step-links {
    margin-top: auto;
}

.left-steps .btn {
    padding: 6px 12px;
    font-size: 12px;
}

/* 左侧步骤的2x2网格样式调整 */
.left-steps .grid-2x2 .step {
    margin-bottom: 0;
    height: 100%;
    display: flex;
    flex-direction: column;
}

/* 中间基础学习的网格样式调整 */
.center-basics .grid-2x2 .learning-card {
    margin: 0;
    height: 100%;
}

/* 右侧进阶升级的网格样式调整 */
.right-advanced .grid-2x2 .advanced-card {
    margin: 0;
    height: 100%;
}

/* 基础学习卡片和进阶升级卡片 */
.learning-card, .advanced-card {
    background: white;
    border-radius: 12px;
    box-shadow: var(--box-shadow);
    padding: 25px 18px;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    position: relative;
    overflow: hidden;
    height: 100%;
    justify-content: space-between;
    min-height: 230px;
}

.learning-card::before, .advanced-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), #5a9eff);
}

.learning-card:hover, .advanced-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 30px rgba(66, 133, 244, 0.1);
}

.card-icon {
    font-size: 28px;
    color: var(--primary-color);
    margin: 0 auto 15px;
    background: rgba(66, 133, 244, 0.1);
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    box-shadow: 0 3px 10px rgba(66, 133, 244, 0.2);
    animation: float 4s ease-in-out infinite;
}

.learning-card:hover .card-icon, .advanced-card:hover .card-icon {
    background: var(--primary-color);
    color: white;
    transform: scale(1.1) rotate(5deg);
}

.learning-card h3, .advanced-card h3 {
    font-size: 18px;
    margin-bottom: 12px;
    color: var(--dark-color);
}

.learning-card p, .advanced-card p {
    margin-bottom: 18px;
    color: var(--gray-color);
    font-size: 14px;
    line-height: 1.5;
    flex: 1;
    display: flex;
    align-items: center;
    overflow-wrap: break-word;
    word-wrap: break-word;
    hyphens: auto;
    max-height: 120px;
    overflow-y: auto;
}

.learning-card .btn, .advanced-card .btn {
    margin-top: auto;
    border-radius: 30px;
    padding: 8px 15px;
    font-size: 13px;
    font-weight: 500;
    letter-spacing: 0.5px;
}

/* 给中间的基础学习卡片和右侧的进阶升级卡片设置不同的颜色主题 */
.center-basics .card-icon {
    background: rgba(0, 112, 243, 0.1);
    color: var(--primary-color);
}

.center-basics .learning-card::before {
    background: linear-gradient(90deg, var(--primary-color), #5a9eff);
}

.center-basics .learning-card:hover .card-icon {
    background: var(--primary-color);
    color: white;
}

.right-advanced .card-icon {
    background: rgba(66, 133, 244, 0.1);
    color: var(--primary-color);
}

.right-advanced .advanced-card::before {
    background: linear-gradient(90deg, var(--primary-color), #5a9eff);
}

.right-advanced .advanced-card:hover .card-icon {
    background: var(--primary-color);
    color: white;
}

.right-advanced .btn {
    background-color: var(--primary-color);
}

.right-advanced h2 {
    color: var(--primary-color);
}

.right-advanced h2::after {
    background: var(--primary-color);
}

/* 2x2网格布局 */
.grid-2x2 {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    grid-template-rows: repeat(2, auto);
    gap: 15px;
    width: 100%;
    margin-bottom: 0;
}

/* 响应式设计调整 */
@media (min-width: 1600px) {
    .three-column-layout {
        max-width: 80%;
    }
    
    .grid-2x2 {
        gap: 20px;
    }
    
    .column h2 {
        font-size: 24px;
        margin-bottom: 22px;
    }
}

@media (max-width: 1400px) {
    .three-column-layout {
        max-width: 95%;
    }
    
    .grid-2x2 {
        aspect-ratio: 1.3 / 1;
    }
}

@media (max-width: 1024px) {
    .three-column-layout {
        grid-template-columns: 1fr 1fr;
        gap: 20px;
        max-width: 95%;
    }
    
    .column {
        padding: 15px;
    }
    
    .right-advanced {
        grid-column: span 2;
    }
    
    .right-advanced .grid-2x2 {
        grid-template-columns: repeat(2, 1fr);
        grid-template-rows: repeat(2, auto);
        gap: 15px;
    }
    
    .learning-card, .advanced-card, .left-steps .step {
        min-height: 220px;
    }
    
    .top-nav {
        position: relative;
        background-color: #4285f4;
    }
    
    header {
        padding: 80px 0 60px;
    }
}

@media (max-width: 900px) {
    .right-advanced .grid-2x2 {
        grid-template-columns: repeat(2, 1fr);
        grid-template-rows: repeat(2, 1fr);
        gap: 15px;
    }
    
    .learning-card, .advanced-card, .left-steps .step {
        min-height: 250px;
    }
}

@media (max-width: 768px) {
    .three-column-layout {
        grid-template-columns: 1fr;
        gap: 25px;
        max-width: 95%;
    }
    
    .right-advanced {
        grid-column: auto;
    }
    
    .main-content {
        padding: 30px 0 50px;
    }
    
    .column h2 {
        font-size: 22px;
        margin-bottom: 18px;
    }
    
    .column {
        padding: 15px;
    }
    
    .grid-2x2 {
        gap: 15px;
    }
    
    .learning-card, .advanced-card, .left-steps .step {
        min-height: 200px;
    }
    
    .top-nav .nav-links {
        display: none;
    }
    
    header h1 {
        font-size: 36px;
    }
    
    header .subtitle {
        font-size: 18px;
    }
    
    .intro h2, .cta h2 {
        font-size: 28px;
    }
    
    .intro p, .cta p {
        font-size: 16px;
    }
    
    .mobile-menu-btn {
        display: block;
        background: none;
        border: none;
        color: white;
        font-size: 24px;
        cursor: pointer;
    }
}

@media (max-width: 480px) {
    .grid-2x2 {
        grid-template-columns: 1fr;
        grid-template-rows: repeat(4, auto);
        gap: 15px;
    }
    
    .right-advanced .grid-2x2 {
        grid-template-columns: 1fr;
        grid-template-rows: repeat(4, auto);
    }
    
    .main-content {
        padding: 25px 0 40px;
    }
    
    .three-column-layout {
        gap: 20px;
        padding: 0 10px;
    }
    
    .column {
        padding: 15px 10px;
    }
    
    .learning-card, .advanced-card, .left-steps .step {
        min-height: 180px;
    }
    
    .learning-card p, .advanced-card p, .left-steps p {
        max-height: none;
        font-size: 13px;
    }
}

/* 添加顶部导航样式 */
.top-nav {
    background-color: rgba(255, 255, 255, 0.1);
    padding: 15px 0;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 10;
}

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

.top-nav .logo {
    color: white;
    font-size: 22px;
    font-weight: 700;
    text-decoration: none;
}

.top-nav .nav-links {
    display: flex;
    gap: 20px;
}

.top-nav .nav-links a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    padding: 5px 10px;
    border-radius: 5px;
    transition: background-color 0.3s;
}

.top-nav .nav-links a:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

/* 修改滚动条样式使其更美观 */
.learning-card p::-webkit-scrollbar,
.advanced-card p::-webkit-scrollbar,
.left-steps p::-webkit-scrollbar {
    width: 4px;
}

.learning-card p::-webkit-scrollbar-track,
.advanced-card p::-webkit-scrollbar-track,
.left-steps p::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 10px;
}

.learning-card p::-webkit-scrollbar-thumb,
.advanced-card p::-webkit-scrollbar-thumb,
.left-steps p::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 10px;
}

.learning-card p::-webkit-scrollbar-thumb:hover,
.advanced-card p::-webkit-scrollbar-thumb:hover,
.left-steps p::-webkit-scrollbar-thumb:hover {
    background: #aaa;
}

/* 添加动画效果 */
@keyframes float {
    0% {
        transform: translateY(0px);
    }
    50% {
        transform: translateY(-10px);
    }
    100% {
        transform: translateY(0px);
    }
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
}

/* 滚动导航样式 */
.top-nav.scrolled {
    background-color: #4285f4;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

/* 移动端菜单样式 */
.mobile-menu {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: white;
    z-index: 1000;
    transform: translateX(-100%);
    transition: transform 0.3s ease;
    display: flex;
    flex-direction: column;
}

.mobile-menu.active {
    transform: translateX(0);
}

.mobile-menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    background-color: #4285f4;
    color: white;
}

.mobile-menu-header span {
    font-size: 20px;
    font-weight: 600;
}

.mobile-menu-close {
    background: none;
    border: none;
    color: white;
    font-size: 20px;
    cursor: pointer;
}

.mobile-menu-links {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.mobile-menu-links a {
    color: #333;
    text-decoration: none;
    font-size: 18px;
    padding: 12px 15px;
    border-radius: 8px;
    transition: all 0.3s;
}

.mobile-menu-links a:hover {
    background-color: #f0f5ff;
    color: #4285f4;
}

/* 平滑滚动 */
html {
    scroll-behavior: smooth;
}

/* 交互式按钮样式 */
.btn-large {
    padding: 12px 30px;
    font-size: 16px;
    position: relative;
    z-index: 1;
    overflow: hidden;
    transition: all 0.3s ease;
}

.btn-large::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateX(-100%);
    transition: transform 0.3s ease;
    z-index: -1;
}

.btn-large:hover::before {
    transform: translateX(0);
}