Right now the toolbar-group in the toolbar (everything from the breakdown selector rightwards) is positioned based on the left part of the toolbar. This can change if "Import..." text in a button is > 78px, so L10N would probably affect this positioning.

We still do a small bit of calc()'ing but much less than before. https://dxr.mozilla.org/mozilla-central/source/devtools/client/themes/memory.css#61 > .devtools-toolbar > .toolbar-group:nth-of-type(1) { > /** > * We want this to be exactly at a `--sidebar-width` distance from the > * toolbar's start boundary. A `.devtools-toolbar` has a 3px start padding. > */ > flex: 0 0 calc(var(--sidebar-width) - 3px); > border-inline-end: 1px solid var(--theme-splitter-color); > margin-inline-end: 5px; > } Do we still want to keep this bug open?

This solution is fine for now, but we might want to change it depending on how we'll want to handle small widths (whether we want to show the sidebar on the top like the Style Editor/Storage Inspector, or whether we want to show it on the left like the perf tool). But if the plan is to leave it as it is, the current code is fine.

Ok, then we can file new bugs if/when that time comes.