לחייב משתמשים לבחור תת-קטגוריה?

What if you add the subcategories links in the modal or with the new topic link?

For example:

Please choose a subcategory below to create a new topic.

<a href="/new-topic?category=parent/subcategory1">Subcategory1</a>
<a href="/new-topic?category=parent/subcategory2">Subcategory2</a>
<a href="/new-topic?category=parent/subcategory3">Subcategory3</a>


And you can modify the button with css. Like this

#create-topic {
  &.btn[disabled]:not(.is-loading),
  &.btn.disabled:not(.is-loading) {
    opacity: 1;
    cursor: pointer;
    &:hover,
    &:focus {
      background: var(--primary-medium);
      color: var(--secondary);
      svg {
        color: var(--secondary);
      }
    }
  }
}