body {
  display: flex;
  align-items: center;
  padding-top: 10px;
  background-color: #f5f5f5;
}

input{
  text-transform: uppercase;
}

.form-signin {
  max-width: 330px;
  padding: 15px;
}

.form-signin .form-floating:focus-within {
  z-index: 2;
}

.form-signin input[type="email"] {
  margin-bottom: -1px;
  border-bottom-right-radius: 0;
  border-bottom-left-radius: 0;
}

.form-signin input[type="password"] {
  margin-bottom: 10px;
  border-top-left-radius: 0;
  border-top-right-radius: 0;
}

html, body {
  height:100%;
  width:100%;
}

body{
background-color:#eee;
display:flex;
align-items:center;
justify-content:center;

}
.card {
 height:400px;
 background-color:white;
 margin:auto;
 width:500px;
 position: relative;

}

.card::after{
 position:absolute;
 bottom:0px;
 left:0px;
 content: ' ';
 background: linear-gradient(to right, #000000, #434343); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */;
 width:100%;
 height:10px;
 filter: blur(10px);
 z-index:-1;

}
/* Con la siguiente sentencia se redondean los bordes */
 div{
   border-radius: 35px;
}

.card2 {
  height:550px;
  background-color:white;
  margin:auto;
  width:400px;
  position: relative;
 
 }
 
 .card2::after{
  position:absolute;
  bottom:0px;
  left:0px;
  content: ' ';
  background: linear-gradient(to right, #000000, #434343); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */;
  width:100%;
  height:10px;
  filter: blur(10px);
  z-index:-1;
 
 }
 /* Con la siguiente sentencia se redondean los bordes */
  div{
    border-radius: 35px;
 }

 .card3 {
  height:550px;
  background-color:white;
  margin:auto;
  width:600px;
  position: relative;
 
 }
 
 .card3::after{
  position:absolute;
  bottom:0px;
  left:0px;
  content: ' ';
  background: linear-gradient(to right, #000000, #434343); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */;
  width:100%;
  height:10px;
  filter: blur(10px);
  z-index:-1;
 
 }
 /* Con la siguiente sentencia se redondean los bordes */
  div{
    border-radius: 35px;
 }