.site-header {
    padding-bottom: 50px;
}
.site-header:before {
    left: 0px;
    right: 0px;
    transform: rotate(0deg);
    clip-path: polygon(0 0, 100% 0, 100% 65%, 0 100%);
}

@media (max-width: 767px) {
    .site-header:before {
        clip-path: polygon(0 0, 100% 0, 100% 75%, 0 100%);
    }
}