Yes, it's typically fine to use a span inside of an h1. span is an inline element, so it's typically okay to use it inside anything (that allows elements inside it!)
And there's not really a cleaner way to do it sometimes, say if you want to style only part of the h1.
On the other hand... don't do it if it's not necessary, as it is a little ugly : )
<!ENTITY % heading "H1|H2|H3|H4|H5|H6">
<!--
There are six levels of headings from H1 (the most important)
to H6 (the least important).
-->
<!ELEMENT (%heading;) - - (%inline;)* -- heading -->
Yes, we can use span tag with header tags and there is nothing wrong in it. Indeed this is widely used for styling header tags, specially for coloring a particular word or letter.
Yes, we can use span tag with header tags and there is nothing wrong in it. Indeed this is widely used for styling header tags, specially for coloring a particular word or letter.