Placing CSS into custom HTML blocks will subject it to corruption by editor processes like wpautop(). Any additional CSS should be placed in the customizer’s Additional CSS section. Your page’s body tag typically has some unique classes you can use to cause your CSS to only be applied to a single page, if that’s what you want.
Only place HTML in the WP editor. Any other code belongs elsewhere. However, if non-HTML code absolutely needs to be within post content for some reason, it can be safely injected via a custom shortcode.
Thank you bcworkz for your return,
I replaced CSS and HTML properly.
I notice that there is some customizations to do evenf if the render is great on a code editor. In fact I had to play with the CSS to recreate the expected result that I had on the code editor.
Thank you again for your precisions 🙂