fix(css): set .mark and <mark> y padding to 0 (#1484)

Signed-off-by: Isabelle Chanclou <isabelle.chanclou@orange.com>
Co-authored-by: Louis-Maxime Piton <louismaxime.piton@orange.com>

scss/_variables.scss

@@ -772,7 +772,7 @@ $dt-font-weight:              $font-weight-bold !default;
 
 $list-inline-padding:         $spacer * .25 !default;
 
-$mark-padding:                .1875em !default;
+$mark-padding:                0 .1875em !default; // Boosted mod
 $mark-bg:                     $primary !default;
 // scss-docs-end type-variables
 // End mod