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HTML 

              
                <button onclick="addTokenFunction()" class="add">Add $UFO To MetaMask</button>
!

CSS 

              
                body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  background-color: #000000;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='250' height='30' viewBox='0 0 1000 120'%3E%3Cg fill='none' stroke='%23222' stroke-width='10' %3E%3Cpath d='M-500 75c0 0 125-30 250-30S0 75 0 75s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3Cpath d='M-500 45c0 0 125-30 250-30S0 45 0 45s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3Cpath d='M-500 105c0 0 125-30 250-30S0 105 0 105s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3Cpath d='M-500 15c0 0 125-30 250-30S0 15 0 15s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3Cpath d='M-500-15c0 0 125-30 250-30S0-15 0-15s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3Cpath d='M-500 135c0 0 125-30 250-30S0 135 0 135s125 30 250 30s250-30 250-30s125-30 250-30s250 30 250 30s125 30 250 30s250-30 250-30'/%3E%3C/g%3E%3C/svg%3E");
}

button {
  background: rgb(85, 0, 255);
  background: linear-gradient(
    90deg,
    rgba(85, 0, 255, 1) 35%,
    rgba(214, 0, 255, 1) 100%
  );
  background-size: 200% 200%;
  border: none;
  padding: 30px 70px;
  border-radius: 40px;
  color: #fff;
  font-size: 20px;
  text-transform: uppercase;
  transition: ease-in all 0.5s;
  animation: button infinite alternate 5s;
}
button:hover {
  cursor: pointer;
}

@keyframes button {
  0% {
    background-position: 0% 50%;
  }
  100% {
    background-position: 100% 70%;
  }
}
!

JS 

              
                const tokenAddress = "0x0683F1cc5f72d088d73DA5558C1927DD648576e0";
const tokenSymbol = "UFO";
const tokenDecimals = 18;
const tokenImage =
  "https://abductingcollective.com/wp-content/uploads/2022/07/ufo-token-logo.jpeg";

async function addTokenFunction() {
  try {
    const wasAdded = await ethereum.request({
      method: "wallet_watchAsset",
      params: {
        type: "ERC20",
        options: {
          address: tokenAddress,
          symbol: tokenSymbol,
          decimals: tokenDecimals,
          image: tokenImage
        }
      }
    });

    if (wasAdded) {
      console.log("Thanks for your interest!");
    } else {
      console.log("HelloWorld Coin has not been added");
    }
  } catch (error) {
    console.log(error);
  }
}
!
999px

Console