.navbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    padding-top: .5rem;
    padding-bottom: .5rem;
    background: linear-gradient(90deg, #512449 0%, #683B46 10%,#8F6143 20%, #B2763A 30%, #B7642D 40%, #A33E1C 50%, 
    #872017 60%, #69131B 70%, #531021 80%, #480004 100%);
    box-shadow: 0 1px 2px #B2763A;
}

.navbar>.container,
.navbar>.container-fluid,
.navbar>.container-lg,
.navbar>.container-md,
.navbar>.container-sm,
.navbar>.container-xl,
.navbar>.container-xxl {
    display: flex;
    flex-wrap: inherit;
    align-items: center;
    justify-content: space-between
}

.navbar-brand {
    padding-top: .3125rem;
    padding-bottom: .3125rem;
    margin-right: 1rem;
    font-size: 1.25rem;
    text-decoration: none;
    white-space: nowrap
}

.navbar a:hover {
    color: #ffffff
}

.navbar>.container {
    width: 100%;
    padding-right: var(--bs-gutter-x, .75rem);
    padding-left: var(--bs-gutter-x, .75rem);
    margin-right: auto;
    margin-left: auto;
}

.nav-item{
    position:relative;
    margin-left: 1vw;
    margin-right: 1vw;
}


.navbar-nav {
    display: flex;
    flex-direction: column;
    padding-left: 0;
    margin-bottom: 0;
    list-style: none;
    margin-left: auto;
}

.navbar-nav .nav-link {
    padding-right: 0;
    padding-left: 0
}

.navbar-nav .dropdown-menu {
    position: static
}

.nav-link {
    display: block;
    padding: .5rem 1rem;
    text-decoration: none;
    transition: color .15s ease-in-out, background-color .15s ease-in-out, border-color .15s ease-in-out
}

@media (prefers-reduced-motion:reduce) {
    .nav-link {
        transition: none
    }
}

.nav-link.disabled {
    color: #6c757d;
    pointer-events: none;
    cursor: default
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    z-index: 1000;
    left: -25%;

    display: flex;
    flex-direction: column;
    max-height: 0;
    overflow: hidden;
    opacity: 0;

    min-width: 10rem;
    padding: .3rem 0;
    background: linear-gradient(to bottom, #FFD9B3 0%, #CC5A00 100%);
    margin: 0;
    font-size: 1rem;
    color: #212529;
    text-align: left;
    list-style: none;
    background-color: #fff;
    background-clip: padding-box;
    border: 1px solid rgba(254, 114, 53, 1);
    border-radius: .25rem;
    transition: max-height 0.4s cubic-bezier(.4,0,.2,1), opacity 0.4s;
}

.nav-item:hover .dropdown-menu {
    max-height: 500px; /* 足够大以容纳所有子项 */
    opacity: 1;
    transition: max-height 0.4s cubic-bezier(.4,0,.2,1), opacity 0.4s;
}
/* 当鼠标放到导航栏某一项时，显示下拉菜单小动画 */
.dropdown-menu > * {
    opacity: 0;
    transform: translateY(-10px);
    transition: opacity 0.3s, transform 0.3s, background-color 0.3s;
    background-color: #FFD9B3; /* 浅橙色 */
}

.nav-item:hover .dropdown-menu > * {
    opacity: 1;
    transform: translateY(0);
}

/* 渐变色：从浅橙到深橙 */
.nav-item:hover .dropdown-menu > *:nth-child(1) {
    transition-delay: 0.05s;
    background-color: #FFD9B3; /* 最浅 */
}
.nav-item:hover .dropdown-menu > *:nth-child(2) {
    transition-delay: 0.12s;
    background-color: #FFC285;
}
.nav-item:hover .dropdown-menu > *:nth-child(3) {
    transition-delay: 0.19s;
    background-color: #FFA94D;
}
.nav-item:hover .dropdown-menu > *:nth-child(4) {
    transition-delay: 0.26s;
    background-color: #FF8C1A;
}
.nav-item:hover .dropdown-menu > *:nth-child(5) {
    transition-delay: 0.33s;
    background-color: #FF7300;
}
.nav-item:hover .dropdown-menu > *:nth-child(6) {
    transition-delay: 0.43s;
    background-color: #CC5A00; /* 最深 */
}

.dropdown-item {
    display: block;
    width: 100%;
    padding: .25rem 1rem;
    clear: both;
    font-weight: 400;
    color: #212529;
    text-align: inherit;
    text-decoration: none;
    white-space: nowrap;
    background-color: transparent;
    border: 0
}

.dropdown-item:focus,
.dropdown-item:hover {
    color: #1e2125;
    background-color: #e9ecef
}

.dropdown-item.active,
.dropdown-item:active {
    color: #fff;
    text-decoration: none;
    background-color: #0d6efd
}

.dropdown-item.disabled,
.dropdown-item:disabled {
    color: #adb5bd;
    pointer-events: none;
    background-color: transparent
}

/* 小窗口下的收纳按钮 */
.navbar-toggler {
    padding: .25rem .75rem;
    font-size: 1.25rem;
    line-height: 1;
    background-color: transparent;
    border: 2px solid white;
    border-radius: .25rem;
    transition: box-shadow .15s ease-in-out;
    box-shadow: 0 0 0 1px #fff;
}

@media (prefers-reduced-motion:reduce) {
    .navbar-toggler {
        transition: none
    }
}

.navbar-toggler:hover {
    text-decoration: none
}

.collapsed.navbar-toggler {
    box-shadow: 0 0 0 0px #fff;
}

.navbar-toggler-icon {
    display: inline-block;
    width: 1.5em;
    height: 1.5em;
    vertical-align: middle;
    background-repeat: no-repeat;
    background-position: center;
    background-size: 100%;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%28255, 255, 255, 0.55%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e")
}


@media (min-width:576px) {
    .navbar-expand-sm {
        flex-wrap: nowrap;
        justify-content: flex-start
    }

    .navbar-expand-sm .navbar-nav {
        flex-direction: row
    }

    .navbar-expand-sm .navbar-nav .dropdown-menu {
        position: absolute
    }

    .navbar-expand-sm .navbar-nav .nav-link {
        padding-right: .5rem;
        padding-left: .5rem
    }

    .navbar-expand-sm .navbar-nav-scroll {
        overflow: visible
    }

    .navbar-expand-sm .navbar-collapse {
        display: flex !important;
        flex-basis: auto
    }

    .navbar-expand-sm .navbar-toggler {
        display: none
    }
}

@media (min-width:768px) {
    .navbar-expand-md {
        flex-wrap: nowrap;
        justify-content: flex-start
    }

    .navbar-expand-md .navbar-nav {
        flex-direction: row
    }

    .navbar-expand-md .navbar-nav .dropdown-menu {
        position: absolute
    }

    .navbar-expand-md .navbar-nav .nav-link {
        padding-right: .5rem;
        padding-left: .5rem
    }

    .navbar-expand-md .navbar-nav-scroll {
        overflow: visible
    }

    .navbar-expand-md .navbar-collapse {
        display: flex !important;
        flex-basis: auto
    }

    .navbar-expand-md .navbar-toggler {
        display: none
    }
}

@media (min-width:992px) {
    .navbar-expand-lg {
        flex-wrap: nowrap;
        justify-content: flex-start
    }

    .navbar-expand-lg .navbar-nav {
        flex-direction: row
    }

    .navbar-expand-lg .navbar-nav .dropdown-menu {
        position: absolute
    }

    .navbar-expand-lg .navbar-nav .nav-link {
        padding-right: .5rem;
        padding-left: .5rem
    }

    .navbar-expand-lg .navbar-nav-scroll {
        overflow: visible
    }

    .navbar-expand-lg .navbar-collapse {
        display: flex !important;
        flex-basis: auto
    }

    .navbar-expand-lg .navbar-toggler {
        display: none
    }
}

@media (min-width:1200px) {
    .navbar-expand-xl {
        flex-wrap: nowrap;
        justify-content: flex-start
    }

    .navbar-expand-xl .navbar-nav {
        flex-direction: row
    }

    .navbar-expand-xl .navbar-nav .dropdown-menu {
        position: absolute
    }

    .navbar-expand-xl .navbar-nav .nav-link {
        padding-right: .5rem;
        padding-left: .5rem
    }

    .navbar-expand-xl .navbar-nav-scroll {
        overflow: visible
    }

    .navbar-expand-xl .navbar-collapse {
        display: flex !important;
        flex-basis: auto
    }

    .navbar-expand-xl .navbar-toggler {
        display: none
    }
}

@media (min-width:1400px) {
    .navbar-expand-xxl {
        flex-wrap: nowrap;
        justify-content: flex-start
    }

    .navbar-expand-xxl .navbar-nav {
        flex-direction: row
    }

    .navbar-expand-xxl .navbar-nav .dropdown-menu {
        position: absolute
    }

    .navbar-expand-xxl .navbar-nav .nav-link {
        padding-right: .5rem;
        padding-left: .5rem
    }

    .navbar-expand-xxl .navbar-nav-scroll {
        overflow: visible
    }

    .navbar-expand-xxl .navbar-collapse {
        display: flex !important;
        flex-basis: auto
    }

    .navbar-expand-xxl .navbar-toggler {
        display: none
    }
}