The higher versions expand on the lower. You only need CSS3 for a web2.0rrhea site where marketing has decided that shiny is better than functional.
HTML5 is similar in relation to HTML4.01. What disappeared are the embedded formatting tags (and unfortunately, you used those rather liberally...)
Overall, the lower CSS specs do improve consistency.
(And as to the browsers still grokking HTML 4.01 Transitional, it is pretty dire. e.g. Edge uses IE7 mode. You're basically chasing rendering bugs in a 12 year old browser.)
HTML5 is similar in relation to HTML4.01. What disappeared are the embedded formatting tags (and unfortunately, you used those rather liberally...)
Overall, the lower CSS specs do improve consistency.
(And as to the browsers still grokking HTML 4.01 Transitional, it is pretty dire. e.g. Edge uses IE7 mode. You're basically chasing rendering bugs in a 12 year old browser.)