fix(css): override inline image background color only when overriding book color, closes #3316 (#3365)

apps/readest-app/src/utils/style.ts

@@ -177,7 +177,7 @@ const getColorStyles = (
     }
     /* inline images */
     *:has(> img.has-text-siblings):not(body) {
-      background-color: ${bg};
+      ${overrideColor ? `background-color: ${bg};` : ''}
     }
     p img.has-text-siblings, span img.has-text-siblings, sup img.has-text-siblings {
       mix-blend-mode: ${isDarkMode ? 'screen' : 'multiply'};