html,
body {
  height: 100%;
}

body {
  display: -ms-flexbox;
  display: flex;
  -ms-flex-align: center;
  align-items: center;
  padding: 20px 0;
  background-color: #f5f5f5;
}

@media (max-width: 340px) {
  body {
    padding: 5px 0;
  }
}

@media (max-width: 639px) {
  .list-group-item {
    padding: .25rem;
  }
}

@media (min-width: 640px) {
  body {
    padding: 40px 0;
  }
}

.form-signin {
  width: 100%;
  max-width: 330px;
  padding: 15px;
  margin: auto;
}
.form-signin .checkbox {
  font-weight: 400;
}
.form-signin .form-control {
  position: relative;
  box-sizing: border-box;
  height: auto;
  padding: 10px;
  font-size: 16px;
}
.form-signin .form-control:focus {
  z-index: 2;
}