zlacker

104 :nth-child(3n){list-style:"Fizz"}:nth-child(5n){list-style:"Buzz"}:nth-child(15n){list-style:"FizzBuzz"}

data:text/html,<style>:nth-child(3n){list-style:"Fizz"}:nth-child(5n){list-style:"Buzz"}:nth-child(15n){list-style:"FizzBuzz"}</style><ol id=o><script>o.innerHTML='<li>'.repeat(99)</script>

>>Metabo+(OP)
103 :nth-child(3n){list-style:"Fizz"}:nth-child(5n){list-style:"Buzz"}:nth-child(15n){list-style:"FizzBuzz"

>>Metabo+E3
98 :nth-child(5n){list-style:""}:nth-child(3n){list-style:"Fizz"}:nth-child(5n)::after{content:"Buzz"

>>Metabo+N3
95 :nth-child(5n){list-style:}:nth-child(3n){list-style:"Fizz"}:nth-child(5n)::after{content:"Buzz

>>Metabo+(OP)
89: :nth-child(3n)::marker{content:"Fizz"var(--b,)}:nth-child(5n){list-style:"Buzz";--b:"Buzz

with help from @bulmenisaurus

>>Metabo+T5
68 :nth-child(3n){list-style:"Fizz"}:nth-child(5n)::after{content:"Buzz

>>Metabo+b6
67 :nth-child(3n){list-style:"Fizz"}:nth-child(5n):after{content:"Buzz

>>eurlei+b8
thank you sir! i can improve the html op css was 152, we have the whole page at 144

data:text/html,<ol id=o><script>o.innerHTML='<li>'.repeat(100)</script><style>:nth-child(3n){list-style:"Fizz"}:nth-child(5n):after{content:"Buzz

>>Metabo+fm
Your code is showing the numbers 5, 10, 20. that's not correct, is it?

Yours prints 1. 2. Fizz 4. 5. Buzz Fizz 7.

But it should be 1. 2. Fizz 4. Buzz Fizz 7.

>>Metabo+b6
This version fails for numbers like 5, showing "5. Buzz". In the case of a number divisible by 5 but not 3 nothing prevents the 5 in the ::marker from rendering.

Edit: it looks like your version can be fixed into a working 85:

  :nth-child(5n){list-style:'';&:after{content:"Buzz"}}:nth-child(3n){list-style:"Fizz"