blockscout/apps/block_scout_web/assets/css/components/_navbar.scss

.navbar {
    position: relative;
    z-index: 100;

    &-primary {
        background-color: $primary;
    }
}

.navbar-collapse.collapsing,
.navbar-collapse.collapse.show {
    display: flex;
    flex-direction: column;

    .search-form {
        align-items: center;
        order: -1;
        width: 100%;

        form {
            flex-grow: 1;
        }
    }
    .input-group {
        width: 100%;
    }
    .navbar-nav {
        white-space: nowrap;
    }
}

.navbar-brand {
    margin-left: 0;
}

.navbar-logo {
    height: 1.5em;
}

@include media-breakpoint-up(md) {
    .navbar-expand-lg .navbar-nav .nav-link {
        padding-left: 0.71rem;
        padding-right: 0.71rem;
    }
}

.navbar {
    .nav-item {
        font-size: 14px;
    }
}

.navbar-dark {
    .navbar-nav {
        .nav-link {
            color: $white;
        }
    }
}

.navbar-nav {
    .nav-link {
        align-items: center;
        display: flex;
        font-size: 14px;
    }
}

.nav-link-icon {
    align-items: center;
    display: flex;
    margin-right: 0.71em;
    position: relative;
    top: -1px;

    path {
        fill: $secondary;
    }
}

.navbar {
    .search-form {
        display: flex;
    }
}

.navbar {
    .form-control {
        background: transparent;
        border-color: transparentize($white, 0.30);
        border-right: none;
        color: $white;
        font-size: 12px;
        padding-right: 0;
        width: auto;

        &::-webkit-input-placeholder {
            /* Chrome/Opera/Safari */
            color: transparentize($white, 0.5);
        }
        &::-moz-placeholder {
            /* Firefox 19+ */
            color: transparentize($white, 0.5);
        }
        &:-ms-input-placeholder {
            /* IE 10+ */
            color: transparentize($white, 0.5);
        }
        &:-moz-placeholder {
            /* Firefox 18- */
            color: transparentize($white, 0.5);
        }
        &:focus {
            box-shadow: none;
        }
        @include media-breakpoint-up(xl) {
            width: calc(41ch + #{$input-padding-x});
        }
    }
}

.navbar {
    .input-group-text {
        background: none;
        border-color: transparentize($white, 0.30);
        border-left: none;
    }
}

.input-group-append {
    margin-left: 0;

    path {
        fill: $secondary;
    }
}

.topnav-nav-link {
    color: $white;
    position: relative;

    &:before {
        background-color: $secondary;
        border-radius: 0 0 4px 4px;
        top: -10px;
        content: "";
        display: block;
        height: 0.25rem;
        left: 50%;
        opacity: 0;
        position: absolute;
        transform: translateX(-50%);
        transition: all 0.2s ease;
        width: 75%;
    }
}

@include media-breakpoint-up(lg) {
    .topnav-nav-link {
        &:hover {
            &:before {
                opacity: 1;
            }
        }
    }
}