[FIX] website: review "lead" paragraphs font-size

The "lead" font-size was not related to the base font size. It now is.
It is especially important since we will allow users to set up the
"lead" style on any text in another PR.

task-3097005

Part-of: odoo/odoo#120302

addons/website/static/src/scss/bootstrap_overridden.scss

@@ -144,7 +144,7 @@ $h6-margin-bottom: o-website-value('h6-margin-bottom') or $headings-margin-botto
 
 $headings-color: o-color('o-cc1-headings') !default;
 
-$lead-font-size: 1.125rem !default;
+$lead-font-size: $font-size-base * $o-lead-ratio !default;
 // Note that we currently load only 700 for Google fonts, we may consider trying
 // to load more or this one only instead. Meanwhile, this fallbacks on 700
 // if 600 is not available anyway.

addons/website/static/src/scss/primary_variables.scss

@@ -2081,6 +2081,9 @@ $o-theme-h4-font-size-multiplier: 1.5 !default;
 $o-theme-h5-font-size-multiplier: 1.25 !default;
 $o-theme-h6-font-size-multiplier: 1 !default;
 
+// Mirror BS default lead multiplier value
+$o-lead-ratio: 1.125 !default;
+
 // Map:
 // <font-name>: (
 //     'family': <css font family list>,