Remove redundant styling from Modal Header

[BPScott]

WHY are these changes introduced?

Modal header titles css look like this:

.Title {
  flex: 1;
  margin-top: spacing(extra-tight);
  word-break: break-word;

  @include breakpoint-after($typography-condensed) {
    margin-top: rem(4px);
  }
}

Both spacing(extra-tight) and rem(4px) resolve to 0.4rem, which means that mixin is pointless.

WHAT is this pull request doing?

Removes that media query.

How to 🎩

Look at the modal dialog in storybook and assert that the title does not change position.

[chloerice]

🔥