CSS minimum opacity value allowed

css, opacity

Solution

Just as @zzzzbov mentioned: `0` is the minimum.

Note: Since `0` means "no opacity", it basically starts from `0.01`

The least is

opacity: 0.01;

The most is:

 opacity: 0.99;

Problem

In CSS when I change the `opacity` value of a button it is still clickable to an extent. I lowered my opacity setting down to `0.005` (so that the button is practically hidden, but it still works and can be interacted with), when I set the value to `0.000000000000000000000000000000000001` though, for example, it just becomes completely hidden and can no longer be clicked. (Surely this tiny float is just rounded to `0`, and this causes the problem, but I'm wondering, just because `0.005` works in my browser, doesn't mean it works in all browsers, and I NEED this button click-able in all browsers). Does anyone know the minimum value it can tolerate across ALL browsers?

Original source