fix(ADA-1689): [Strategic Blue / University of Sheffield] - highlight…

… search text within the video (#219)

Issue:
when you search in the text box, the strings that match to the search text have orange background and the text is white. it doesn't have good contrast

Fix:
change text color to black

solves ADA-1689

src/components/caption/caption.scss

@@ -58,7 +58,7 @@
       }
     }
     .highlight-search {
-      color: $secondary-text-contrast-color;
+      color: $tone-8-color;
       background-color: $secondary-color;
       border-radius: 2px;
       &::selection {