/* 全局基础样式 */
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Microsoft Yahei", system-ui, -apple-system, sans-serif;
}
html,body{
    height: 100%;
    scroll-behavior: smooth;
}
body{
    background-color: #ffffff;
    color: #1d2129;
    line-height: 1.55;
    padding-top: 60px; /* 给固定导航留出顶部高度，避免内容被遮挡 */
}
.container{
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 16px;
}

/* 顶部导航栏 固定悬浮置顶，永远不会被滚动带走 */
.top-nav-bar{
    width: 100%;
    background-color: #2574eb;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 9999; /* 最高层级，不会被任何内容盖住 */
}
.nav-inner{
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 16px;
    height: 60px;
    flex-wrap: nowrap !important;
}
.logo-box img{
    height: 46px;
    vertical-align: middle;
    max-width: 240px;
    width: auto;
    display: block;
    flex-shrink: 0;
}
.nav-menu{
    display: flex;
    height: 100%;
    flex-wrap: nowrap !important;
}
.nav-item{
    height: 100%;
    display: flex;
    align-items: center;
    padding: 0 12px;
    position: relative;
}
.nav-item a{
    color: #ffffff;
    text-decoration: none;
    font-size: 15px;
    white-space: nowrap;
    opacity: 0.78;
}
.nav-item.active a{
    opacity: 1;
}
.nav-item.active::after{
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 65%;
    height: 4px;
    background: #fff;
    border-radius: 99px;
}

/* 移动端汉堡按钮 */
.menu-toggle{
    display: none;
    color: #fff;
    font-size: 32px;
    cursor: pointer;
    user-select: none;
    padding: 0 10px;
}

/* 移动端下拉菜单 强制初始隐藏，层级置顶 */
.mobile-menu{
    position: absolute;
    top: 60px;
    left: 0;
    width: 100%;
    background: #1b62cc;
    text-align: center;
    z-index: 9998;
    display: none !important;
}
.mobile-menu.show{
    display: block !important;
}
.mobile-menu a{
    display: block;
    color: #fff;
    padding: 14px 0;
    text-decoration: none;
    border-bottom: 1px solid rgba(255,255,255,0.12);
    font-size: 16px;
}

/* 手机端媒体查询 强制生效 */
@media only screen and (max-width:768px){
    .nav-menu{
        display: none !important;
    }
    .menu-toggle{
        display: block !important;
    }
    .nav-inner{
        height: 60px;
        flex-wrap: nowrap !important;
    }
}

/* 赞助商区域 */
.sponsor-title{
    text-align: center;
    font-size: 22px;
    margin-bottom: 24px;
}
.sponsor-grid{
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 14px;
    margin-bottom: 70px;
}
@media (max-width:768px){
    .sponsor-grid{
        grid-template-columns: repeat(2, 1fr);
    }
}
.sponsor-item{
    border: 1px solid #eee;
    border-radius: 10px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8px;
}
.sponsor-item a{
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}
.sponsor-item img{
    max-width: 85%;
    max-height: 55px;
    object-fit: contain;
}

/* 友情链接 */
.friend-wrap{
    background: linear-gradient(180deg,#f0f7ff,#ffffff);
    padding: 24px 0 40px;
    text-align: center;
}
.friend-wrap h4{
    font-size: 22px;
    margin-bottom: 20px;
    color: #333;
}
.friend-group{
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    justify-content: center;
}
.friend-item{
    border: 1px solid #c6ddff;
    color: #2574eb;
    padding: 10px 30px;
    border-radius: 999px;
    font-size: 16px;
    background: #fff;
    text-decoration: none;
}
.friend-item:hover{
    background: #e6f0ff;
}