adambisek
Validate relation to font-size
Could you validate that you consider the font size correctly? Plus maybe add a thought on "px" vs. "pt" vs. "em"? For example: "Provide the font size in pixels. Other units like pt, em, and rem are not supported".
Your size calculator creates a <span> element with a font-size: 100; CSS property. However, the number 100 without a unit of measure seems to be no acceptable value for the font-size property. Correct would be to provide it as 100px.
Providing the font size without unit will make the calculated size depend on a lot of things, such as surrounding HTML elements etc. In your calculator's page, ultimately the defaults hard-coded into the browser the page runs in, will apply. According to the StackOverflow response linked above, this will usually be something smaller than 100px.
