React Js Validate a Bitcoin Address

<!DOCTYPE html>
<html>

return (
        <div className='container'>
          <h3 className='heading'>React Js Bitcoin Address Validator</h3>
          <input
            type="text"
            className='input-field'
            placeholder="Enter a Bitcoin address"
            value={address}
            onChange={(e) => setAddress(e.target.value)}
          />
          <button className='validate-button' onClick={validateAddress}>
            Validate Address
          </button>
          {isMessageVisible && (
            <p className='message'>
              {isValid
                ? <span style={{ color: 'green' }}>The Bitcoin address is valid.</span>
                : <span style={{ color: 'red' }}>The Bitcoin address is not valid.</span>
              }
            </p>
          )}

</div>

);

}
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>

.container {
      margin: 0 auto;
      width: 600px;
      text-align: center;
      box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
      padding: 20px;
    }

heading {
      font-size: 24px;
      margin-bottom: 20px;
      color: #333;
    }

.input-field {
      padding: 10px;
      width: 300px;
      border: 1px solid #ccc;
      border-radius: 5px;
      font-size: 16px;
      margin-bottom: 10px;
      outline: none;
    }

.validate-button {
      padding: 10px 20px;
      background-color: #007BFF;
      color: #fff;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      font-size: 18px;
      transition: background-color 0.3s;
    }

.validate-button:hover {
      background-color: #0056b3;
    }

.message {
      font-size: 18px;
      margin-top: 20px;
      color: #007BFF;
    }
  </style>
</body>

</html>