The default signup form looks like this:
<form method="POST" class="panel">
<input name="response_type" value="id_token token" type="hidden">
<input name="client_id" value="4bc2c80e-7518-4e8e-bc1d-99b3b870bbbd" type="hidden">
<input name="redirect_uri" value="https://apples.anvil.io/callback" type="hidden">
<input name="max_age" type="hidden">
<input name="scope" value="openid profile email realm" type="hidden">
<input name="state" type="hidden">
<input name="nonce" value="ZeFcFFVRYWx9AS5Y1wjOC_ppFnwonPkyvULGgZjcm8o" type="hidden">
<input name="givenName" placeholder="First Name" type="text">
<input name="familyName" placeholder="Last Name" type="text">
<input name="email" placeholder="Email" type="text">
<input name="password" placeholder="Password" type="password">
<input value="Sign up" type="submit">
</form>