Hello,
As you see on my site and as mentioned I managed to transparency, but I do not know how. By cons I do not see what I changed from the CSS?
Yes of course I will use a child theme that I will be more advanced.
By now against this is to provide set my own way the text box and slider to change the fonts and background color of the text block.
If you noted aberrations, do not hesitate to let me know.
Otherwise I also love, apart from the home page back to the original theme (no slider or slider background) leaving only the logo and site description
bests regards
silvan