Adding tags for h1

[Starhunter]

Hello all.

1) Does Google or the other search engines differentiate between a clear and simple <h1> tag and one as a class, ie. <h1 class="xr_tl Heading_1" style= . . .">? If so, has that been proven somehow, such as a direct comparison using both? I assume in theory Google would know it was the same, but would like some confirmation. Semrush and ahrefs point out that overly complex code, as opposed to those that have most style material in a separate css file, could affect SEO negatively. Both sites also marked my missing <h1> tags as an error to be fixed.

2) If it's still not proven, then how best to get it placed? I did use the placeholder technique, but as another user mentioned, that's a bit sloppy and varies by browser or screen size. I never tried comparing it with mobile. I have used all versions from WD 7 to recent.

Thanks for any help.