UI: Make document body a flexbox

[silverwind]

Fixes: #6118

Also got rid of @footer-margin which added 40px padding on bottom of some pages. Did that in the parent instead, so now the graph page also has some needed padding at the bottom.

[codecov-io]

Codecov Report

Merging #6139 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6139      +/-   ##
==========================================
- Coverage   38.88%   38.88%   -0.01%     
==========================================
  Files         354      354              
  Lines       50184    50184              
==========================================
- Hits        19516    19514       -2     
- Misses      27842    27844       +2     
  Partials     2826     2826

Impacted Files	Coverage Δ
models/repo_list.go	66.84% <0%> (-1.06%)	⬇️

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[lafriks]

Did you check on ie11?

[silverwind]

Not yet, but Firefox, Chrome and Safari all look well.

[silverwind]

IE11 appears to affected by some kind of flexbug, not sure. Somehow flex: 1 has no effect on .full.height and the footer floats.

What's the plan for IE11? I dropped support in most of my projects, maybe we can too?

[silverwind]

Removing flex: 1 and giving the footer a explicit height of 40px appears to solve it on IE11, so weird.

[lafriks]

I think we still should support IE11 as that is latest IE version

[silverwind]

IE 11 fixed and rebased. This should be ready to review.