Article layout is not using Isomer Next colour and type tokens

[sehyunidaaa]

Problem

• The article layout wasn't using the right tokens, it was using the old tailwind tokens. So the typography was a little off from other layouts.
• The title in the article layout is smaller than the Section Title.

Closes [ISO-161]

This is with the section title:

Solution

• Use the right tokens to match designs here https://www.figma.com/design/rsKQdmtyoOWawyAv1LkJJK/Isomer-Next-Component-Library?node-id=584-18886&t=mOp7e01PcMxtGaj3-1
• [Caveat] Using display-md for the title. This means that the article title and Section Title are the same size, but we can't fix it without rejigging the entire typographic scale.

[linear]

ISO-161 Section heading is too big on Article page

[datadog-opengovsg]

Datadog Report

Branch report: sehyun/iso-161-section-heading-is-too-big-on-article-page
Commit report: 753b567
Test service: isomer-studio

✅ 0 Failed, 266 Passed, 36 Skipped, 49.63s Total Time
➡️ Test Sessions change in coverage: 1 no change