fix: logo icon briefly disappears and reappears during theme change (#543)

* fix: add width specification to .navbar__logo to avoid layout change during theme change

* fix: logo icon briefly disappears and reappears during theme change

add space line at the end of file

Co-authored-by: Kevin Cui <github@bugs.cc>

* fix: logo icon briefly disappears and reappears during theme change

Modify comments, links to issue 539

Co-authored-by: Kevin Cui <github@bugs.cc>

---------

Co-authored-by: Kevin Cui <github@bugs.cc>

src/css/custom.scss

@@ -250,3 +250,8 @@
 .table-of-contents__link--active {
   font-weight: var(--ifm-font-weight-bold);
 }
+
+// fix https://github.com/electron/website/issues/539
+.navbar__logo {
+  width: 2rem;
+}