<style>
  body{ background-color: #FBFBFB;}
  #nav-mobile li a{ color: teal;}
  .brand-logo{margin-top: 5px;}
  .container{width: 90%;}
  #span{color:red}
  #btn-login{ margin: 20px 0px;}
  .form-div{ margin-top: 20px;}
</style>

<nav>
  <div class="nav-wrapper white">
    <a href="#" class="brand-logo valign-wrapper"><img style="width: 180px" src="./static/images/logo.jpg"></a>
  </div>
</nav>
<br><br>
<div class="container">
      <form class="row">
        <div class="card col s10 offset-s1 ">
         <div class="form-group col s6 offset-s3 form-div">
            <label class="teal-text" for="input-id">Usuario</label>
            <input type="text" class="form-control" id="input-name-user" name="usuario" placeholder="usuario">
        </div>
        <div class="form-group col s6 offset-s3">
            <label class="teal-text" for="input-name">Contraseña</label>
            <input type="password" class="form-control" id="input-password" name="contraseña" placeholder="contraseña">
        </div>
        <br>
        <br><br><br>
        <div class=" col s3 offset-s3">
        <button id="btn-login" class="waves-effect waves-light btn">Enviar</button>
        </div>
        <div class="col s6">
          <span id="span"></span>
        </div>
        </div>
      </form>
      <br><br>
      <a href="formregister" id="btn-open-register">Regístrate</a>
</div>