X in close icon is misaligned when I change the font size in the tab bar

Steps to Reproduce

Add the following to styles.less: .tab-bar { font-size: 16px; }
Save the file with Cmd+S

Expected: X in close icon to be properly aligned
Actual: Close icon X is off-center

Versions

Atom

Atom: 1.20.0-dev-372cef218
Electron: 1.6.9
Chrome: 56.0.2924.87
Node: 7.4.0

apm

apm  1.18.3
npm  3.10.10
node 6.9.5 x64
python 2.7.13
git 2.13.3

OS

Mac OS X 10.12.6

Additional Info

Installed Packages

* about * advanced-open-file * archive-view * atom-2048 * atom-dark-syntax * atom-dark-ui * atom-light-syntax * atom-light-ui * autocomplete-atom-api * autocomplete-css * autocomplete-emojis * autocomplete-html * autocomplete-html-entities * autocomplete-plus * autocomplete-snippets * autoflow * autosave * background-tips * badges * base16-tomorrow-dark-theme * base16-tomorrow-light-theme * block-travel * bookmarks * bracket-matcher * chmod * command-palette * convert-date * dalek * deprecation-cop * dev-live-reload * docblockr * double-tag * encoding-selector * exception-reporting * file-icons * file-type-icons * find-and-replace * fonts * fuzzy-finder * git-diff * github * github-atom-light-syntax * go-to-line * grammar-selector * hex * highlight-selected * image-view * incompatible-packages * indentation-indicator * keybinding-resolver * language-c * language-clojure * language-coffee-script * language-csharp * language-css * language-diff * language-elixir * language-generic-config * language-gfm * language-git * language-go * language-html * language-hyperlink * language-java * language-javascript * language-json * language-less * language-make * language-mustache * language-objective-c * language-pegjs * language-perl * language-php * language-property-list * language-python * language-ruby * language-ruby-on-rails * language-rust * language-sass * language-shellscript * language-slim * language-source * language-sql * language-text * language-todo * language-toml * language-typescript-grammars-only * language-xml * language-yaml * less-than-slash * line-ending-selector * link * markdown-helper * markdown-mindmap * markdown-preview * metrics * minimap-plus * notifications * one-dark-syntax * one-dark-ui * one-light-syntax * one-light-ui * open-on-github * package-generator * package-sync * pretty-json * real-time * red-wavy-underline * right-case * set-syntax * settings-view * significant-other * snippets * soft-wrap-indicator * solarized-dark-syntax * solarized-light-syntax * sort-lines * spell-check * status-bar * styleguide * symbols-view * tabs * tabs-to-spaces * timecop * toggle-quotes * town-crier * tree-view * update-package-dependencies * welcome * whitespace * wrap-guide

atom / one-light-ui