/* 
 * sczhlp.com - AI大模型学习官网
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 */

/* ========== CSS 变量定义 ========== */
:root {
    --color-white: #ffffff;
    --color-light-green: #e8f5e9;
    --color-medium-green: #a5d6a7;
    --color-deep-green: #4caf50;
    --color-light-pink: #fce4ec;
    --color-medium-pink: #f48fb1;
    --color-deep-pink: #e91e63;
    --color-text-dark: #2c3e50;
    --color-text-gray: #666666;
    --color-border: #eeeeee;
    --shadow-soft: 0 4px 20px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.12);
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius-card: 16px;
    --border-radius-btn: 50px;
}

/* ========== 全局重置 ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--color-white);
    color: var(--color-text-dark);
    line-height: 1.8;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition-smooth);
}

ul {
    list-style: none;
}

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

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
}

/* ========== 顶部导航栏 ========== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: transparent;
    transition: var(--transition-smooth);
}

.header.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-soft);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 40px;
    max-width: 1400px;
    margin: 0 auto;
}

.logo {
    font-size: 28px;
    font-weight: bold;
    color: var(--color-deep-green);
    letter-spacing: 2px;
}

.logo span {
    color: var(--color-deep-pink);
}

.nav-menu {
    display: flex;
    gap: 40px;
}

.nav-menu a {
    font-size: 16px;
    font-weight: 500;
    position: relative;
    padding: 8px 0;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-deep-green), var(--color-deep-pink));
    transition: var(--transition-smooth);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-deep-green);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 28px;
    height: 3px;
    background: var(--color-text-dark);
    transition: var(--transition-smooth);
}

/* ========== 页脚 ========== */
.footer {
    background: linear-gradient(135deg, var(--color-light-green) 0%, var(--color-white) 50%, var(--color-light-pink) 100%);
    padding: 80px 0 40px;
    margin-top: 100px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 60px;
    margin-bottom: 60px;
}

.footer-section h4 {
    font-size: 18px;
    margin-bottom: 24px;
    color: var(--color-deep-green);
}

.footer-section p,
.footer-section a {
    color: var(--color-text-gray);
    font-size: 14px;
    line-height: 2.2;
}

.footer-section a:hover {
    color: var(--color-deep-pink);
}

.social-links {
    display: flex;
    gap: 16px;
    margin-top: 20px;
}

.social-links a {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--color-white);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-soft);
    transition: var(--transition-smooth);
}

.social-links a:hover {
    transform: translateY(-4px);
    background: var(--color-deep-green);
    color: var(--color-white);
}

.footer-bottom {
    text-align: center;
    padding-top: 40px;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-gray);
    font-size: 14px;
}

/* ========== 通用动画 ========== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-15px);
    }
}

.animate-in {
    animation: fadeInUp 0.8s ease-out forwards;
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    .container {
        padding: 0 24px;
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
        gap: 40px;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 80px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 80px);
        background: var(--color-white);
        flex-direction: column;
        align-items: center;
        justify-content: flex-start;
        padding-top: 60px;
        gap: 30px;
        transition: var(--transition-smooth);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hamburger {
        display: flex;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .container {
        padding: 0 20px;
    }
}