main {
  padding-top: 1rem;
}

.signup-title {
  text-align: center;
  font-size: 1.8rem;
  color: #ff5454;
}

.signup-form {
  padding: 1rem;
  display: grid;
  grid-row-gap: .5rem;
  grid-row-gap: .25rem;
  /* works better when label displaced down */
  grid-auto-rows: 2rem;
  align-items: center;
}

.signup-form label {
  font-weight: bold;
}

.signup-form>label {
  /* I added this 'cause I didn't like way labels and inputs were separated. */
  position: relative;
  top: .55rem;
}

.signup-form label,
.signup-form select,
.signup-form input {
  display: block;
  width: 100%;
}


/* .signup-form input(type="checkbox") {} */


/* this would be how you might normally do it. As an exercise, I guess, are doing the below instead */


/* Also could use 
.signup-form [for*="terms"] 
for label */

.signup-form [id*="terms"],
.signup-form [id*="terms"]+label {
  display: inline-block;
  /* want block-level features, like top margin */
  width: auto;
  vertical-align: bottom;
}

.signup-form input:not([type="checkbox"]),
.signup-form select {
  border: 1px solid #ccc;
  padding: 0.2rem 0.5rem;
  font: inherit;
}

.signup-form input:focus,
.signup-form select:focus {
  outline: none;
  background: #d8f3df;
  border-color: #2ddf5c;
}

.signup-form input[type="checkbox"] {
  border: 1px solid #ccc;
  background: white;
  width: 1rem;
  height: 1rem;
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
}

.signup-form input[type="checkbox"]:checked {
  background: #2ddf5c;
  border: #0e4f1f;
}

.signup-form button[type="submit"] {
  display: block;
  position: relative;
}

.signup-form input.invalid,
.signup-form select.invalid,
.signup-form :invalid {
  border-color: red !important;
  background: rgb(250, 172, 172);
}

.signup-form button[type="submit"]:after {
  position: absolute;
  top: 3rem;
  left: -5.4rem;
  content: attr(data-content);
  height: 4rem;
  width: 40rem;
  opacity: 1;
}

.signup-form button[type="submit"]:after:hover {
  opacity: 1;
}

@media (min-width: 40rem) {
  .signup-form {
    margin: auto;
    width: 30rem;
    grid-template-columns: 10rem auto;
    /* justify-content: center; */
    grid-row-gap: 1rem;
    grid-column-gap: .5rem;
  }
  .signup-form #title {
    grid-column: span 2;
  }
  .signup-form__checkbox {
    grid-column: span 2;
  }
}