On monitors/screens that are oriented vertically (ie: portrait), the left sidebar consumes too great a proportion of the page.

A second, but related issue, is that the diff/code panel does not scroll:auto its content, it's simply truncated with no scrollbar.

Overall not a great UX.

It would be useful to have buttons for "previous file in changeset", "next file in changeset" (ideally with keyboard shortcuts), so that portrait users can easily step through diffs without having to open/close the sidebar for every file.

The diff/code panel should probably have scrollbar, as the only way to see very long lines is to resize the window across 2-3 monitors (bad) or select the text to scroll to end, or add CSS overrides to force long lines to wrap:

.stash-theme .CodeMirror-code

.stash-theme .CodeMirror-sizer

.stash-theme .CodeMirror pre