style(theme): Enhance section styling and comment out unused variables

Improved the layout and styling of sections to ensure better visual
consistency and maintainability. Commented out unused CSS variables to
prevent potential conflicts and improve clarity.

- Commented out CSS variable definitions for primary, secondary,
  tertiary, and text colors to prevent unintended style overrides.
- Added `position: relative` to section elements to facilitate absolute
  positioning of child elements.
- Removed top margin for the second child elements of various types
  within sections to ensure consistent spacing.
- Positioned `bc-footer` elements absolutely at 80px from the bottom of
  sections to maintain a consistent footer placement.
- Eliminated bottom margin for the last child elements within
  `bc-footer` to ensure a clean and uniform footer appearance.

Signed-off-by: Glenn Y. Rolland <glenux@glenux.net>

.marp/theme.scss

@@ -7,10 +7,12 @@ $tertiaryColor: #241c1c;
 $textColor: #111111;
 
 body {
+  /*
   --primary-color: $primaryColor;
   --secondary-color: $secondaryColor;
   --tertiary-color: $tertiaryColor;
   --text-color: $textColor;
+  */
 }
 
 section {
@@ -257,3 +259,28 @@ p img:only-child[alt*="center"] {
   margin-right: auto;
 }
 
+section {
+  position: relative;
+}
+
+section > h2:nth-child(2),
+section > h3:nth-child(2),
+section > h4:nth-child(2),
+section > h5:nth-child(2),
+section > h6:nth-child(2),
+section > p:nth-child(2),
+section > bc-row:nth-child(2),
+section > ul:nth-child(2) > li:first-child > p {
+  margin-top: 0;
+}
+
+section bc-footer { 
+  position: absolute;
+  bottom: 80px;
+}
+
+section bc-footer *:last-child {
+  margin-bottom: 0;
+}
+
+