Creating custom buttons with CSS (Everything went wrong)

I am trying to make a custom button for my website. Website: https://www.ecoflame.ca/
The buttons I am tempering with are on the landing page of the website.

Here's the CSS code I am trying to inject:
https://uiverse.io/shah1345/spicy-liger-32

I am replacing all ".button2" with .sqs-block-button-element--medium sqs-button-element--primary sqs-block-button-element

OR simply ".sqs-block-button-element"
The result is janky. The resulting button shows the current and the intended hover effect at the same time. 

I am using the "Custom CSS" menu to do that. What am I doing wrong here?

Because some SS core code overrides your code. You need to add !important to some attributes to override these code. Use this new code

.button-block a {
  display: inline-block;
  transition: all 0.2s ease-in;
  position: relative;
  overflow: hidden;
  z-index: 1;
  color: #090909;
  padding: 0.7em 1.7em;
  font-size: 18px;
  border-radius: 0.5em;
  background: #e8e8e8;
  border: 1px solid #e8e8e8;
  box-shadow: 6px 6px 12px #c5c5c5,
             -6px -6px 12px #ffffff;
}

.button-block a:active {
  color: #666;
  box-shadow: inset 4px 4px 12px #c5c5c5,
             inset -4px -4px 12px #ffffff;
}

.button-block a:before {
  content: "";
  position: absolute !important;
  left: 50% !important;
  transform: translateX(-50%) scaleY(1) scaleX(1.25) !important;
  top: 100% !important;
  width: 140%;
  height: 180%;
  background-color: rgba(0, 0, 0, 0.05) !important;
  border-radius: 50% !important;
  display: block;
  transition: all 0.5s 0.1s cubic-bezier(0.55, 0, 0.1, 1);
  z-index: -1 !important;
}

.button-block a:after {
  content: "";
  position: absolute;
  left: 55%;
  transform: translateX(-50%) scaleY(1) scaleX(1.45);
  top: 180%;
  width: 160%;
  height: 190%;
  background-color: #009087;
  border-radius: 50%;
  display: block;
  transition: all 0.5s 0.1s cubic-bezier(0.55, 0, 0.1, 1);
  z-index: -1;
}

.button-block a:hover {
  color: #ffffff;
  border: 1px solid #009087;
}

.button-block a:hover:before {
  top: -35%;
  background-color: #009087;
  transform: translateX(-50%) scaleY(1.3) scaleX(0.8);
}

.button-block a:hover:after {
  top: -45%;
  background-color: #009087;
  transform: translateX(-50%) scaleY(1.3) scaleX(0.8);
}