metamask-extension/ui/components/component-library/text-field-base/text-field-base.scss

.mm-text-field-base {
  --text-field-base-height: var(--size, 40px);

  &--size-sm {
    --size: 32px;
  }

  &--size-md {
    --size: 40px;
  }

  &--size-lg {
    --size: 48px;
  }

  height: var(--text-field-base-height);
  border-color: var(--color-border-default);

  &--focused {
    outline: 5px auto Highlight; // firefox
    outline: 5px auto -webkit-focus-ring-color; // chrome
  }

  &--error {
    border-color: var(--color-error-default);
  }

  &--disabled {
    opacity: 0.5;
    border-color: var(--color-border-default);
  }

  // truncates text with ellipsis
  &--truncate .mm-text-field-base__input {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  &__input {
    border: none;
    height: 100%;
    flex-grow: 1;
    box-sizing: content-box;
    margin: 0;
    padding: 0;

    &:focus,
    &:focus-visible {
      outline: none;
    }
  }
}