Does height and width not apply to span?

Try using a div instead of the span or using the CSS display: block; or display: inline-block;—span is by default an inline element which cannot take width and height properties.

Inspired from @Hamed, I added the following and it worked for me:

display: inline-block; overflow: hidden; 

Span is an inline element. It has no width or height.

You could turn it into a block-level element, then it will accept your dimension directives.

span.product__specfield_8_arrow
{
    display: inline-block; /* or block */
}