Can someone please help me?

I’m creating the site northwalestweets.com and am having problems with:

1 text not displaying correctly, and
2 Twitter and Facebook feeds not showing in some browsers.

The text problem appears mainly to affect text that I’ve changed from the standard style I’m using (Arial 20pt) to large font, coloured, bold, italic etc.

Instead of displaying the text as intended, some browsers are showing large fonts as small, coloured text as plain, other text as overlaid on itself, plus other undesirable variations.

It’s particularly noticeable on the mobile variant, with Safari and Chrome currently not displaying properly (though Chrome was perfect yesterday evening!).

The attached image is from the Testimonials page, on Chrome.Click image for larger version.  Name: IMG_3016.PNG  Views: 56  Size: 178.2 KB  ID: 124653

Opera Touch is currently giving the best mobile display.

Firefox on my phone is showing the text correctly, but won’t show the Twitter or Facebook feeds – yet the desktop version is perfect (as it is when viewed with Chrome and Edge too).

The site isn't yet on general release, but is at http://www.northwalestweets.com/public_html/index-1.htm.

Does anyone have any idea what’s going on, please - and what I can do about it?