Why artefacts appear in the mobile version?

Good afternoon, outlined the design on bootstrap. Can't understand why the mobile version of the appearance menu in the bottom of the page appear artifacts.
If you make a fixed height and overflow it, lose the scroll menu.

July 9th 19 at 11:21
1 answer
July 9th 19 at 11:23
Read here.

html {
 position: fixed;
 /*min-height: 100%;*/

 direction: ltr;
 height: auto;

Change relative to fixed
in this case, the scroll disappears altogether. - Linnea_Willms commented on July 9th 19 at 11:26

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