body{
  font-family: sans-serif;
  background: #ebf9fb;
}
 
h1{
  text-align: center;
  /*ketebalan font*/
  font-weight: 300;
}
 
.tulisan_login{
  text-align: center;
  /*membuat semua huruf menjadi kapital*/
  text-transform: uppercase;
}
 
.kotak_login{
  width: 350px;
  background: white;
  /*meletakkan form ke tengah*/
  margin: 80px auto;
  padding: 30px 20px;
  box-shadow: 0px 0px 100px 4px #d6d6d6;
}
 
label{
  font-size: 11pt;
}
 
.form_login{
  /*membuat lebar form penuh*/
  box-sizing : border-box;
  width: 100%;
  padding: 10px;
  font-size: 11pt;
  margin-bottom: 20px;
}
 
.tombol_login{
  background: #2aa7e2;
  color: white;
  font-size: 11pt;
  width: 100%;
  border: none;
  border-radius: 3px;
  padding: 10px 20px;
}
 
.link{
  color: #232323;
  text-decoration: none;
  font-size: 10pt;
}
 
.alert{
  background: #e44e4e;
  color: white;
  padding: 10px;
  text-align: center;
  border:1px solid #b32929;
}



<form action="cek_login.php" method="post">
