Having selected the correct text for highlighting, it is important to ensure proper alignment of the baseline and height of the initial letter highlight relative to the other lines of text. This doesn't work well without help from the dedicated CSS properties, initial-letters and the initial-letters-align. Unfortunately, only Safari supports the first property, and it requires the -webkit prefix, so this is still an immature feature.

Safari aligns the alphabetic baseline of the highlighted text with that on the specified number of lines. The relationship between the highlighted letters and the first line of the paragraph appears to be based on cap height, but is not clear. The requirements for that relationship are not yet really clear, despite the information in Indian Layout Requirements.

The impact here is advanced, since it is mainly needed for advanced layouts.