metamask-extension/ui/components/component-library/modal-content/modal-content.scss

.mm-modal-content {
  --modal-content-size: var(--size, 360px);

  // Currently there is only use case for one size of ModalContent in the extension
  // See audit https://www.figma.com/file/hxYqloYgmVcgsoiVqmGZ8K/Modal-Audit?node-id=481%3A244&t=XITeuRB1pRc09hiG-1
  // Not to say there won't be more in the future, but to prevent redundant code there is only one for now
  &--size-sm {
    --size: 360px;

    max-width: var(--modal-content-size);
  }

  position: relative;
  box-shadow: var(--shadow-size-lg) var(--color-shadow-default);
  max-height: calc(100% - 32px); // allow for 16px padding on top and bottom
  overflow: auto;
}