fix(dark-mode): increase text selection opacity for better visibility (#2642)

Co-authored-by: terminalchai <213856599+terminalchai@users.noreply.github.com>
Co-authored-by: codecalm <codecalm@gmail.com>

.changeset/fix-dark-mode-selection-contrast.md

@@ -0,0 +1,5 @@
+---
+"@tabler/core": patch
+---
+
+Fixed dark mode text selection contrast by adding `--tblr-selection-bg` CSS variable with `0.4` opacity override in dark mode.

core/scss/_variables.scss

@@ -598,6 +598,8 @@ $active-bg: color-transparent(var(--#{$prefix}primary), 0.04) !default;
 $active-color: var(--#{$prefix}primary) !default;
 $active-border-color: var(--#{$prefix}primary) !default;
 
+$selection-bg: light-dark(color-transparent(var(--#{$prefix}primary), 0.1), color-transparent(var(--#{$prefix}primary), 0.4)) !default;
+
 $hover-bg: color-transparent(var(--#{$prefix}secondary), 0.08) !default;
 
 $disabled-bg: var(--#{$prefix}bg-surface-secondary) !default;

core/scss/ui/_type.scss

@@ -171,7 +171,7 @@ Selection
  */
 ::selection,
 .text-selected {
-  background-color: color-transparent(var(--#{$prefix}primary), 0.1);
+  background-color: $selection-bg;
 }
 
 .text-selected {