Fix monospace font size for .mono CSS class (#13453)

web_src/less/helpers.less

@@ -4,7 +4,7 @@
 .js { justify-content: flex-start; }
 .je { justify-content: flex-end; }
 .sb { justify-content: space-between; }
-.mono { font-family: var(--fonts-monospace); }
+.mono { font-family: var(--fonts-monospace); font-size: .9em; /* compensate for monospace fonts being usually slighty larger */ }
 .rounded { border-radius: var(--border-radius) !important; }
 .word-break { word-wrap: break-word; word-break: break-all; }