Hey Massaki,
you do not have any unique wrappers around the subheadings, they are just bold text, which is why they’re not aligning. You can try this:
.page-id-280 .page-content strong { float: left; margin-left: -52%; }
yet I would recommend wrapping the headings you need left-aligned into divs with unique identifiers (class or id), which would make it easier to add attributes to them.
Sincerely,
Andrii / Satori Studio