Fix button text color overridden by region link color rules

[jjroelofs]

Linked issues

• Fix button text color overridden by region link color rules #765

Summary

Region-level a { color: ... } CSS rules override Bootstrap button text colors when buttons use <a> elements. This is the same bug class fixed in PR #726 for cards.

Problem

Bare a selectors in region SCSS set link colors that bleed into <a class="btn ..."> elements:

• .dxpr-theme-header a { color: headertext } — overrides btn-primary/btn-secondary text color
• .dxpr-theme-main-menu a { color: headertext } — same issue in main menu
• #secondary-header a { color: secheadertext } — affects buttons in secondary header
• .dxpr-theme-footer a { color: footertext } — affects buttons in footer
• .region-sidebar-first/second a { color: text } — affects sidebar buttons
• .content .list-inline a { color: text } — affects inline list buttons

Solution

Apply a:not(.btn) exclusion to all affected selectors, matching the pattern from PR #726.

Files Changed

• scss/components/dxpr-theme-header.scss — 2 selectors updated (lines 32, 72)
• scss/components/dxpr-theme-secondary-header.scss — 1 selector updated (line 12)
• scss/base/layout.scss — 1 selector updated (footer, line 259)
• scss/base/typography.scss — 2 selectors updated (lines 109, 215)
• Compiled CSS for all above

Checklist

• I have read the CONTRIBUTING.md document.
• My commit messages follow the contributing standards and style of this project.
• My code follows the coding standards and style of this project.
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• All new and existing tests passed.