How to stop the page reload when click the button on blazor web assembly application

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Blazor

I had develop the login application. when I sign I had consumed the api but page completely reload after click the sign button. I don't want reload just execute the logic only. This is the blazor web assembly application.

<main class="form-signin">
  <form>    
    <img class="mb-4" src="/MainLogo.png" alt="" width="72" height="57">
    <h1 class="h3 mb-3 fw-normal">Please sign in</h1>

    <div class="form-floating">
      <input type="email" class="form-control" id="floatingInput" @bind="username" placeholder="name@example.com">
      <label for="floatingInput">Email address</label>
    </div>
    <div class="form-floating">
      <input type="password" class="form-control" id="floatingPassword" @bind="password" placeholder="Password">
      <label for="floatingPassword">Password</label>
    </div>

    <div class="checkbox mb-3">
      <label>
        <input type="checkbox" value="remember-me"> Remember me
      </label>
    </div>
    <button class="w-100 btn btn-lg btn-primary"  @onclick="sign">Sign in</button>
    <p class="mt-5 mb-3 text-muted">© 2017–2021</p>
  </form>
</main>

protected async void sign()
    {
        Dictionary<string, string> keyvalues = new Dictionary<string, string>();
        keyvalues.Add("userName", username);
        keyvalues.Add("password", password);

        var client = ClientFactory.CreateClient("WebAPI");

        var request = new HttpRequestMessage(HttpMethod.Post,"api/Account/Login");

        var content = JsonConvert.SerializeObject(keyvalues);

        StringContent stringContent = new StringContent(content, System.Text.Encoding.UTF8,"application/json");

        HttpResponseMessage response = await client.PostAsync(request.RequestUri, stringContent);


    }

What I have tried:

I had develop the login application. when I sign I had consumed the api but page completely reload after click the sign button. I don't want reload just execute the logic only.