netbox/netbox/project-static/styles/transitional/_forms.scss

// Limit the width of object edit forms
form.object-edit {
  margin: auto;
  max-width: 800px;
}

// Use <h3> style for field group headings
.field-group {
  h2 {
    @extend h3;
  }
}

// Set bond font & append an asterisk to labels for required fields
.col-form-label.required {
  font-weight: bold;
  &:after {
    position: absolute;
    display: inline-block;
    margin-left: 0;
    font-family: 'Material Design Icons';
    font-size: 8px;
    content: '\f06C4';
  }
}

// Set red border on form fields inside a row with .has-errors
.has-errors {
  input,
  select,
  textarea {
    border: 1px solid $red;
  }
}

// Make optgroup labels sticky when scrolling through select elements
select[multiple] {
  optgroup {
    position: sticky;
    top: 0;
    background-color: var(--bs-body-bg);
    font-style: normal;
    font-weight: bold;
  }
  option {
    padding-left: 0.5rem;
  }
}

// Filter modifier dropdown sizing
.modifier-select {
  min-width: 10rem;
  max-width: 15rem;
  width: auto;
  white-space: nowrap;
}