According to this thread, you can override the default orange outline by overriding
-webkit-tap-highlight-color
from
-webkit-tap-highlight-color: rgba(255, 255, 255, 0);
in your css file (you need to create a css file and add it if you don't have one). The last value of 0 sets the alpha value to effectively make the color invisible (1 fully visible). If this is not the exact css style you are looking for, you can refer to other webkit styles to find similar ads.
Supports Joe McCann for the idea.
Mcstretch
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