Dropped `.radio-inline` and `.checkbox-inline`.
- Renamed `.input-lg` and `.input-sm` to `.form-control-lg` and `.form-control-sm`, respectively.
- Dropped `.form-group-*` classes for simplicity's sake. Use `.form-control-*` classes instead now.
- Dropped `.help-block` and replaced it with `.form-text` for block-level help text. For inline help text and other flexible options, use utility classes like `.text-muted`.
+- Dropped `.radio-inline` and `.checkbox-inline`.
- Horizontal forms overhauled:
- Dropped the `.form-horizontal` class requirement.
- `.form-group` no longer applies styles from the `.row` via mixin, so `.row` is now required for horizontal grid layouts (e.g., `<div class="form-group row">`).