Can't change button transition duration

Site URL: https://pufferfish-llama-7l86.squarespace.com

Hi,

I have been trying to speed up button hover effects but the css code I am using has no effect:

"

.sqs-block-button-element:hover {
background-color: rgba(0, 0, 0, 1) !important;
transition-duration: all 0s !important;
  transition-delay: all 0s !important
}

"

The background-colour line has the desired effect so I thought the transition-duration line would also work, but it has no effect. 

Any suggestions?

Liam