/* 主导航唯一样式入口：文字直达总览，独立箭头控制展开。 */
.ud-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 99;
    transition: background-color 0.2s ease, box-shadow 0.2s ease;
}
.ud-header--light {
    background: rgba(255, 255, 255, 0.96);
    border-bottom: 1px solid var(--bfk-border);
}
.ud-header.sticky {
    backdrop-filter: blur(5px);
    box-shadow: inset 0 -1px 0 0 rgba(0, 0, 0, 0.1);
}
.ud-header:not(.ud-header--light).sticky { background: rgba(255, 255, 255, 0.8); }
.bfk-site-nav { padding: 0; border-radius: 5px; position: relative; }
.bfk-site-nav .navbar-brand { padding: 0; }
.bfk-site-nav .navbar-brand img { display: block; max-width: 160px; height: auto; filter: var(--bfk-logo-filter); }
.bfk-site-nav .navbar-toggler { padding: 0; }
.bfk-site-nav .toggler-icon {
    width: 30px;
    height: 2px;
    background: var(--bfk-text-primary);
    display: block;
    margin: 5px 0;
    position: relative;
    transition: transform 0.2s ease, opacity 0.2s ease;
}
.bfk-site-nav .navbar-toggler.active .toggler-icon:nth-of-type(1) { transform: rotate(45deg); top: 7px; }
.bfk-site-nav .navbar-toggler.active .toggler-icon:nth-of-type(2) { opacity: 0; }
.bfk-site-nav .navbar-toggler.active .toggler-icon:nth-of-type(3) { transform: rotate(135deg); top: -7px; }

.bfk-site-nav .nav-item { position: relative; padding: 0 8px; }
.bfk-site-nav .nav-item > a {
    font-size: 16px;
    font-weight: 400;
    color: var(--bfk-text-primary);
    padding: 25px 8px;
    position: relative;
    transition: color 0.2s ease;
}
.bfk-site-nav .nav-item > a:hover,
.bfk-site-nav .nav-item > a.active { color: var(--bfk-primary); }
.bfk-site-nav .nav-item-has-children { display: flex; align-items: center; flex-wrap: wrap; }
.bfk-site-nav .nav-item-has-children > a { padding-right: 0; }
.bfk-site-nav .nav-trigger {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 44px;
    padding: 0;
    border: 0;
    border-radius: 4px;
    background: transparent;
    color: var(--bfk-text-primary);
}
.bfk-site-nav .nav-trigger::after {
    content: "";
    width: 6px;
    height: 6px;
    margin-top: -3px;
    border-right: 1.5px solid;
    border-bottom: 1.5px solid;
    transform: rotate(45deg);
}
.bfk-site-nav .nav-trigger[aria-expanded="true"]::after { transform: rotate(225deg); margin-top: 3px; }
.bfk-site-nav .nav-trigger:hover,
.bfk-site-nav .nav-trigger[aria-expanded="true"] { color: var(--bfk-primary); }
.bfk-site-nav :is(a, button):focus-visible { outline: 2px solid var(--bfk-primary); outline-offset: 3px; }
.bfk-site-nav .ud-submenu {
    display: none;
    position: absolute;
    width: 250px;
    top: 100%;
    left: 0;
    padding: 24px;
    background: var(--bfk-white);
    border: 1px solid var(--bfk-border);
    border-radius: 5px;
    box-shadow: var(--bfk-shadow-sm);
}
.bfk-site-nav .ud-submenu.show { display: block; }
.bfk-site-nav .nav-item-catalog { position: static; }
.bfk-site-nav .nav-catalog { width: min(960px, calc(100vw - 48px)); left: 50%; transform: translateX(-50%); }
.bfk-site-nav #help-submenu { left: auto; right: 0; }
.bfk-site-nav .nav-mobile-action { display: none; }
.nav-product-groups { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 32px; }
.nav-product-groups > div + div { border-left: 1px solid var(--bfk-border); padding-left: 24px; }
.nav-product-groups > div:first-child ul { display: grid; grid-template-columns: 1fr 1fr; gap: 0 20px; }
.nav-solution-groups { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.nav-solution-groups > div + div { border-left: 1px solid var(--bfk-border); padding-left: 32px; }
.nav-solution-links { display: grid; grid-template-columns: 1fr 1fr; gap: 0 16px; }
.nav-group-title { color: var(--bfk-body-color); font-size: 13px; font-weight: 600; margin: 0 0 12px; }
.bfk-site-nav .ud-submenu-link { display: block; font-size: 14px; line-height: 1.7; padding: 8px 0; color: var(--bfk-text-primary); }
.bfk-site-nav .ud-submenu-link:hover { color: var(--bfk-primary); }
.bfk-site-nav .nav-catalog .ud-submenu-link { display: flex; align-items: center; gap: 10px; min-height: 44px; border-radius: 5px; }
.bfk-site-nav .nav-catalog .ud-submenu-link .lni { flex: 0 0 20px; width: 20px; font-size: 19px; color: var(--bfk-primary); text-align: center; }
.bfk-site-nav .nav-catalog .ud-submenu-link span { min-width: 0; }
.bfk-site-nav .navbar-btn { display: flex; flex-shrink: 0; gap: 8px; }
.bfk-site-nav .navbar-btn .ud-main-btn { padding: 11px 15px; }

@media (min-width: 992px) {
    .ud-header:not(.ud-header--light):not(.sticky) .nav-item > a { color: var(--bfk-white); }
}
@media (min-width: 992px) and (max-width: 1199px) {
    .bfk-site-nav .navbar-brand { max-width: 120px; }
    .bfk-site-nav .nav-item { padding: 0 2px; }
    .bfk-site-nav .nav-item > a { padding-left: 4px; padding-right: 4px; }
    .bfk-site-nav .nav-item-has-children > a { padding-right: 0; }
    .bfk-site-nav .nav-trigger { width: 22px; }
    .bfk-site-nav .navbar-btn .ud-main-btn { padding: 10px; }
}
@media (max-width: 991px) {
    .bfk-site-nav .navbar-brand { padding: 5px 0; }
    .bfk-site-nav .navbar-collapse {
        display: none;
        position: absolute;
        top: 100%;
        right: 0;
        width: 100%;
        max-height: calc(100dvh - 100px);
        overflow-y: auto;
        overscroll-behavior: contain;
        background: var(--bfk-white);
        z-index: 9;
        box-shadow: var(--bfk-shadow-sm);
        border-radius: 5px;
    }
    .bfk-site-nav .navbar-collapse.show { display: block; }
    .bfk-site-nav .navbar-nav { padding: 16px 22px; }
    .bfk-site-nav .nav-item { padding: 0; }
    .bfk-site-nav .nav-item > a { display: block; padding: 8px 0; }
    .bfk-site-nav .nav-item-has-children > a { flex: 1; }
    .bfk-site-nav .nav-trigger { width: 44px; }
    .bfk-site-nav .ud-submenu { position: static; width: 100%; flex-basis: 100%; border: 0; padding: 12px 0 20px; box-shadow: none; }
    .bfk-site-nav .nav-catalog { left: 0; transform: none; }
    .bfk-site-nav .navbar-btn { position: absolute; top: 50%; right: 50px; transform: translateY(-50%); }
    .nav-product-groups { grid-template-columns: 1fr; gap: 24px; }
    .nav-product-groups > div + div { border-left: 0; padding-left: 0; }
    .nav-product-groups ul { display: grid; grid-template-columns: 1fr 1fr; gap: 0 16px; }
    .nav-solution-groups { grid-template-columns: 1fr; gap: 20px; }
    .nav-solution-groups > div + div { border-left: 0; padding-left: 0; }
    .nav-solution-links { gap: 0 12px; }
}
@media (max-width: 575px) {
    .bfk-site-nav .navbar-btn { display: none; }
    .bfk-site-nav .nav-mobile-action { display: block; }
}