/* ========== 基础 ========== */
* { margin:0; padding:0; box-sizing:border-box; }
body { font-family: -apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',sans-serif; color:#334155; background:#f8fafc; line-height:1.6; }
.container { max-width:1200px; margin:0 auto; padding:0 20px; }
a { text-decoration:none; color:inherit; }
img { max-width:100%; display:block; }

/* 按钮 */
.btn { display:inline-flex; align-items:center; justify-content:center; gap:8px; padding:12px 28px; border-radius:50px; font-weight:600; transition:all 0.3s; border:none; cursor:pointer; font-size:1rem; }
.btn-primary { background:#f97316; color:#fff; box-shadow:0 8px 20px rgba(249,115,22,0.3); }
.btn-primary:hover { background:#ea580c; transform:translateY(-2px); box-shadow:0 12px 25px rgba(249,115,22,0.4); }
.btn-outline { border:2px solid #f97316; color:#f97316; background:transparent; }
.btn-outline:hover { background:#f97316; color:#fff; }
.btn-sm { padding:8px 20px; font-size:0.9rem; }

/* ========== 导航栏（全新设计） ========== */
.header {
    position:fixed; top:0; left:0; width:100%; z-index:1000;
    background: rgba(255,255,255,0.8); backdrop-filter: blur(20px);
    box-shadow: 0 1px 20px rgba(0,0,0,0.05);
    transition: all 0.3s ease;
}
.header.scrolled { background: rgba(255,255,255,0.95); box-shadow: 0 2px 25px rgba(0,0,0,0.1); }
.header-inner { display:flex; align-items:center; justify-content:space-between; height:70px; }
.logo { display:flex; align-items:center; gap:8px; font-size:1.4rem; font-weight:700; color:#1e293b; }
.logo img { height:36px; }
.logo span { background: linear-gradient(135deg, #f97316, #ea580c); -webkit-background-clip:text; -webkit-text-fill-color:transparent; }

/* 导航列表 */
.nav-list { display:flex; align-items:center; gap:10px; list-style:none; margin-right:20px; }
.nav-list li { position:relative; }
.nav-list a {
    display:block; padding:8px 16px; border-radius:10px; color:#475569; font-weight:500;
    transition: color 0.3s, background 0.3s; position:relative; white-space:nowrap;
}
/* 滑动下划线 */
.nav-list a::after {
    content:''; position:absolute; bottom:2px; left:50%; transform:translateX(-50%) scaleX(0);
    width:20px; height:3px; background:#f97316; border-radius:3px; transition:transform 0.3s;
}
.nav-list a:hover { color:#f97316; background:rgba(249,115,22,0.05); }
.nav-list a:hover::after { transform:translateX(-50%) scaleX(1); }
/* 当前页激活样式 */
.nav-list a.active { color:#f97316; background:rgba(249,115,22,0.1); }
.nav-list a.active::after { transform:translateX(-50%) scaleX(1); width:24px; }

/* 登录按钮（桌面端显示在导航右侧） */
.header-login-btn { display:inline-flex; }

/* 移动端汉堡按钮 */
.mobile-menu-btn {
    display:none; flex-direction:column; justify-content:center; align-items:center;
    width:40px; height:40px; background:transparent; border:none; cursor:pointer; z-index:1001;
}
.mobile-menu-btn span {
    display:block; width:24px; height:2px; background:#334155; border-radius:2px;
    transition: all 0.3s; margin:3px 0;
}
/* 汉堡菜单动画（变为X） */
.mobile-menu-btn.open span:nth-child(1) { transform:rotate(45deg) translate(5px,5px); }
.mobile-menu-btn.open span:nth-child(2) { opacity:0; }
.mobile-menu-btn.open span:nth-child(3) { transform:rotate(-45deg) translate(5px,-5px); }

/* 移动端菜单容器 */
@media (max-width: 768px) {
    .nav-list {
        display:none; flex-direction:column; position:absolute; top:70px; left:0;
        width:100%; background:#fff; padding:20px; box-shadow:0 10px 25px rgba(0,0,0,0.1);
        border-radius:0 0 20px 20px; gap:5px;
    }
    .nav-list.active { display:flex; animation: slideDown 0.3s ease; }
    .mobile-menu-btn { display:flex; }
    .header-login-btn { display:none; } /* 桌面端登录按钮隐藏，改用菜单项 */
}

@keyframes slideDown {
    from { opacity:0; transform:translateY(-10px); }
    to { opacity:1; transform:translateY(0); }
}