Fix auto-generated everforest obsidian theme readability issues (#2752)

* Fix auto-generated everforest obsidian theme

* Update `--text-muted` and `--text-faint` to be readable against
background color

* Add contrast detection and color correction logic

* Remove dedicated Obsidian CSS file

* Add dedicated text color variables to obsidian theme generation

* Replace closest color logic with generated color for code bg in Obsidian

---------

Co-authored-by: David Heinemeier Hansson <david@hey.com>

bin/omarchy-theme-set-obsidian

@@ -87,6 +87,35 @@ calculate_brightness() {
   echo $(((r * 299 + g * 587 + b * 114) / 1000))
 }
 
+# Calculate approximate contrast ratio between two colors
+# Returns ratio scaled by 100 (e.g., 450 = 4.5:1 ratio)
+# (this is due to bash not supporting decimal math)
+calculate_contrast_ratio() {
+  local hex1="$1" hex2="$2"
+  local br1=$(calculate_brightness "$hex1")  # 0-255 range
+  local br2=$(calculate_brightness "$hex2")  # 0-255 range
+
+  # Ensure br1 is the lighter color (higher brightness)
+  if [ $br1 -lt $br2 ]; then
+    local temp=$br1
+    br1=$br2
+    br2=$temp
+  fi
+
+  # Approximate contrast ratio scaled by 100
+  # Add offset to avoid division by zero and approximate WCAG +0.05 behavior
+  echo $(((br1 + 13) * 100 / (br2 + 13)))
+}
+
+# Check if two colors meet minimum contrast threshold
+# Usage: meets_contrast_threshold <ratio> <threshold>
+# Both ratio and threshold should be scaled by 100 (e.g., 300 = 3:1)
+meets_contrast_threshold() {
+  local ratio="$1"        # Ratio scaled by 100 (from calculate_contrast_ratio)
+  local threshold="$2"    # Threshold scaled by 100 (300=3:1, 450=4.5:1, 700=7:1)
+  [ $ratio -ge $threshold ]
+}
+
 # Calculate color distance (euclidean in RGB space)
 color_distance() {
   local hex1="$1"
@@ -229,38 +258,30 @@ extract_theme_data() {
     fi
   done
 
-  # Sort by distance and get the closest color for code background
-  local -a closest_to_bg
-  readarray -t closest_to_bg < <(printf '%s\n' "${bg_distances[@]}" | sort -n | head -1 | cut -d: -f2)
-
   # All background variations use the same as primary background
   local bg_primary_alt="$bg_color"
   local bg_secondary="$bg_color"
   local bg_secondary_alt="$bg_color"
 
-  # Code block background uses the closest different color
+  # Generate code background color that will contrast with foreground text
-  local code_bg="${closest_to_bg[0]}"
+  read -r r g b <<<"$(hex_to_rgb "$bg_color")"
-
+  if [ $bg_brightness -gt 127 ]; then
-  # If no different color available, create a subtle variant for code blocks
+    r=$((r - 10))
-  if [ -z "$code_bg" ]; then
+    g=$((g - 10))
-    read -r r g b <<<"$(hex_to_rgb "$bg_color")"
+    b=$((b - 10))
-    if [ $bg_brightness -gt 127 ]; then
+  else
-      r=$((r - 10))
+    r=$((r + 15))
-      g=$((g - 10))
+    g=$((g + 15))
-      b=$((b - 10))
+    b=$((b + 15))
-    else
-      r=$((r + 15))
-      g=$((g + 15))
-      b=$((b + 15))
-    fi
-    [ $r -lt 0 ] && r=0
-    [ $r -gt 255 ] && r=255
-    [ $g -lt 0 ] && g=0
-    [ $g -gt 255 ] && g=255
-    [ $b -lt 0 ] && b=0
-    [ $b -gt 255 ] && b=255
-    code_bg=$(printf "#%02x%02x%02x" "$r" "$g" "$b")
   fi
+  [ $r -lt 0 ] && r=0
+  [ $r -gt 255 ] && r=255
+  [ $g -lt 0 ] && g=0
+  [ $g -gt 255 ] && g=255
+  [ $b -lt 0 ] && b=0
+  [ $b -gt 255 ] && b=255
+  code_bg=$(printf "#%02x%02x%02x" "$r" "$g" "$b")
+
 
   # Find closest color to foreground for code block text
   local code_fg=""
@@ -345,6 +366,22 @@ extract_theme_data() {
     border_color=$(printf "#%02x%02x%02x" "$r" "$g" "$b")
   fi
 
+  # Set text colors for muted/faint based on contrast
+  local text_muted_color="$border_color"
+  local text_faint_color="$border_color"
+
+  # Validate border color contrast against background
+
+  # Represents a 3:1 WCAG contrast ratio
+  local ideal_contrast_ratio=300
+
+  local border_contrast=$(calculate_contrast_ratio "$border_color" "$bg_color")
+  if ! meets_contrast_threshold "$border_contrast" "$ideal_contrast_ratio"; then
+    # Override text colors for readability, keep border color for visibility
+    text_muted_color="$fg_color"
+    text_faint_color="$fg_color"
+  fi
+
   # Get unique colors array (without bg/fg) sorted by frequency
   local -a unique_colors
   readarray -t unique_colors < <(echo "$filtered_data" | sort_colors_by_frequency)
@@ -409,8 +446,8 @@ extract_theme_data() {
   --text-mark: ${color_slots[7]};
   --interactive-accent: ${color_slots[8]};
   --blockquote-border: ${color_slots[9]};
-  --text-muted: $border_color;  /* Use border color for muted text */
+  --text-muted: $text_muted_color;  /* Use text-specific color for muted text */
-  --text-faint: $border_color;  /* Use border color for faint text */
+  --text-faint: $text_faint_color;  /* Use text-specific color for faint text */
 
   /* Additional mappings */
   --text-accent: var(--interactive-accent);