This is an example of a loading bar animation, designed using HTML, CSS, Bootstrap framework 4. The body of the form is given the styles of display as flex, justify-content as center, align-items as center, height as 100vh, and background as #ECEFFC. The implementation of the loading feature has been done by giving different animations and styles into four bars. The loading container is given the styles of position as relative, width as 45px, height as 45px, and a transform value as rotate(75deg). An individual bar is given an animation of 1.5s cubic-bezier(0.645, 0.045, 0.355, 1) infinite. The first child element is given a background color of #0984e3, and an animation style of slide-bottom-top, whereas the second child element has the background color of #d63031, and animation style of slide-left-right. The third and fourth ones are given the background colors and animation styles of #fdcb6e, #00b894, slide-top-bottom, and slide-right-left, respectively. Source: https://codepen.io/alphardex/pen/abzaxBB

This is a web form with an animated CSS loader designed using pure CSS, and Bootstrap framework 4. The colors and sizes of the loader are predefined as $p: 6.25em, $r: 1.5em, $b: 20*$r, $d: 2*($b - $r), $c: /#490a3d, /*#bd1550,*/ #e97f02/*, $n: length($c), $q: 20%, and $t: 1s. The background of the form is given the styles of background color as #333, and filter as drop-shadow(2px 2px 5px rgba(#000, .5)). The body of the form is given the styles of display as grid, place-content as center, height as 100vh, and animation as fsx 4*$t steps(1) infinite. The loader switches its background color between #490a3d, and #e97f02. It is given an animation of fbg 2*$n*$t steps(1) -3*$t infinite, mov $t infinite alternate, and exp $t ease-in infinite alternate. When the mov becomes 100%, it is given a transform of translatey($r) rotate(.5turn). Source: https://codepen.io/thebabydino/pen/YzPoZyj