Fix tooltip styling inconsistency

This commit fixes inconsistent tooltip styling by setting the font
explicitly on the tooltip container to ensure uniform tooltip fonts.

As tooltip is rendered inside the parent elements' DOM, styling parent
element's font was also styling the font's font due to style
propogation, but setting fonts explicitly on tooltip ensure this does
not happen.

src/presentation/assets/styles/_mixins.scss

@@ -128,3 +128,8 @@
   $calculated-width-in-em: calc(#{$estimated-width-per-character-in-em} * #{$value-in-ch});
   #{$property}: $calculated-width-in-em;
 }
+
+@mixin base-font-style {
+  font-family: $font-family-main;
+  font-size: $font-size-absolute-normal;
+}

src/presentation/assets/styles/base/_index.scss

@@ -21,9 +21,7 @@ $base-spacing: 1em;
 
 body {
   background: $color-background;
-  font-family: $font-family-main;
-  font-size: $font-size-absolute-normal;
-
+  @include base-font-style;
   @include apply-uniform-spacing($base-spacing: $base-spacing)
 }