/* ========================================
   鼎途网络 - 全局样式文件
   研学专业风 | 天蓝 + 浅灰 + 纯白
   ======================================== */

/* CSS Reset & 基础设置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    line-height: 1.8;
    color: #333;
    background-color: #f5f7fa;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

ul, ol {
    list-style: none;
}

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

/* 颜色变量 */
:root {
    --primary-blue: #4A90E2;
    --light-blue: #87CEEB;
    --sky-blue: #E3F2FD;
    --dark-blue: #1E3A5F;
    --light-gray: #F5F7FA;
    --medium-gray: #9CA3AF;
    --dark-gray: #4B5563;
    --pure-white: #FFFFFF;
    --text-dark: #1F2937;
    --border-color: #E5E7EB;
}

/* 容器 */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

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

/* ========================================
   顶部导航栏
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: transparent;
    transition: all 0.4s ease;
}

.header.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
    backdrop-filter: blur(10px);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo img {
    height: 45px;
    width: auto;
}

.logo-text {
    font-size: 24px;
    font-weight: 700;
    color: var(--pure-white);
    letter-spacing: 2px;
}

.header.scrolled .logo-text {
    color: var(--primary-blue);
}

.nav-menu {
    display: flex;
    gap: 8px;
}

.nav-menu li {
    position: relative;
}

.nav-menu a {
    display: block;
    padding: 12px 24px;
    color: var(--pure-white);
    font-size: 15px;
    font-weight: 500;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.header.scrolled .nav-menu a {
    color: var(--text-dark);
}

.nav-menu a:hover,
.nav-menu a.active {
    background: var(--primary-blue);
    color: var(--pure-white);
    transform: translateY(-2px);
}

/* 汉堡菜单 */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 28px;
    height: 3px;
    background: var(--pure-white);
    border-radius: 2px;
    transition: all 0.3s ease;
}

.header.scrolled .hamburger span {
    background: var(--text-dark);
}

/* ========================================
   通用按钮样式
   ======================================== */
.btn {
    display: inline-block;
    padding: 14px 36px;
    font-size: 16px;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-blue), var(--light-blue));
    color: var(--pure-white);
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(74, 144, 226, 0.4);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary-blue);
    color: var(--primary-blue);
}

.btn-outline:hover {
    background: var(--primary-blue);
    color: var(--pure-white);
}

/* ========================================
   页面过渡动画
   ======================================== */
.page-transition {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.page-transition.loaded {
    opacity: 1;
    transform: translateY(0);
}

/* 滚动渐入动画 */
.scroll-reveal {
    opacity: 0;
    transform: translateY(50px);
    transition: all 0.8s ease;
}

.scroll-reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

/* ========================================
   页脚样式
   ======================================== */
.footer {
    background: linear-gradient(135deg, var(--dark-blue), #2C3E50);
    color: var(--pure-white);
    padding: 60px 0 30px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    font-size: 18px;
    margin-bottom: 20px;
    color: var(--light-blue);
    position: relative;
    padding-bottom: 10px;
}

.footer-section h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background: var(--primary-blue);
}

.footer-section ul li {
    margin-bottom: 12px;
}

.footer-section ul li a {
    color: #B0B8C4;
    font-size: 14px;
    transition: all 0.3s ease;
}

.footer-section ul li a:hover {
    color: var(--light-blue);
    padding-left: 8px;
}

.footer-contact p {
    color: #B0B8C4;
    font-size: 14px;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 30px;
    text-align: center;
    color: #8895A4;
    font-size: 14px;
}

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

@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: 80px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 80px);
        background: var(--pure-white);
        flex-direction: column;
        padding: 30px;
        gap: 10px;
        transition: all 0.4s ease;
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-menu a {
        color: var(--text-dark);
        padding: 16px 20px;
        border-radius: 8px;
    }

    .nav-menu a:hover,
    .nav-menu a.active {
        background: var(--sky-blue);
        color: var(--primary-blue);
    }

    .header-inner {
        padding: 15px 20px;
    }

    .footer-grid {
        grid-template-columns: 1fr;
    }

    .container,
    .container-narrow {
        padding: 0 15px;
    }
}

/* ========================================
   工具类
   ======================================== */
.text-center { text-align: center; }
.text-primary { color: var(--primary-blue); }
.mt-20 { margin-top: 20px; }
.mt-40 { margin-top: 40px; }
.mb-20 { margin-bottom: 20px; }
.mb-40 { margin-bottom: 40px; }
.p-40 { padding: 40px; }

.section-padding {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 60px;
}

.section-title h2 {
    font-size: 36px;
    color: var(--text-dark);
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.section-title h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-blue), var(--light-blue));
    border-radius: 2px;
}

.section-title p {
    color: var(--dark-gray);
    font-size: 16px;
    max-width: 600px;
    margin: 20px auto 0;
}