Change default font-size to 14px

[vanillajonathan]

Changes the default font-size from 12px to a more modern 14px used by other editors such as CodeMirror and Monaco.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.60%. Comparing base (4c6cf13) to head (451b176).
⚠️ Report is 258 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@ ## master #5449 +/- ## ======================================= Coverage 87.60% 87.60% ======================================= Files 584 584 Lines 46463 46463 Branches 7023 7023 ======================================= Hits 40705 40705 Misses 5758 5758 

Flag	Coverage Δ
unittests	87.60% <ø> (ø)

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[vanillajonathan]

@nightwing Maybe you can merge this?