Sunnyside agency landing page

For the triangle you can use ::before pseudo-element on the container, using display absolute to positioning it on the top right corner. And for achieve the shape you can use clip-path CSS property clip-path: polygon(100% 0, 100% 100%, 0 100%).

@AndresHense You can the triangle by using the border property

create a element <div class="shape"></div> add css

.shape{
    border-bottom: 100px solid green;
    border-left: 100px solid transparent;
}

then give it a fixed position position: fixed to the top left corner of the mobile menu