I play in Firefox, screen resolution 1920x1080, and I have to zoom out to 60% to be able to play normally regardless if my window is fullscreen or resized. By "play normally", I mean that I can't see the "Start Quest" button, or properly see quest rewards unless I drastically zoom out because the page design is... not well optimized.

The reputation bar is a clutterbug. So is the flavor text that's outside of the little box with the NPC image. On the "finished quest" page, I do not need to see the items I've turned in because I don't care for them - I turned them in, I'm done with them. If I need that information, it's already listed in the quest history. (The flavor text itself could do with a bit of a trim/rewrite, especially with the implied text formatting/italics that don't work, but that's for another post.)

If a visual example will be more useful in getting things across, I have mockups below, with before/after screenshots.

Perfectly well put together feedback, and the mockup looks indeed way more cleaner. As a returning player, I appreciate the quality of life on Kumos by making me not go back and forth with the website to finish a quest, or having multiple tabs open, but it is visually bothering to look at thing sometimes.

Just to add a thought to that, specially since you mentioned flavor text, I personally don't like how small the NPCs portraits became, there's a lot of text and information on Kumos, while on Legacy it felt simple, interactive and straightfoward, showing exactly the NPC and their dialogue. On Kumos, I feel like I'm talking more to boxes and not looking at the NPCs. Probably some people don't care, but the characters and their portraits were what made Subeta very much alive.

Understandable, and I agree that the Kumos text is very chunky (and sometimes feels out-of-character) compared to legacy. Copy/pasting the legacy quest flavor text (before starting quest/while questing/finishing quest) to Kumos would be ideal - there's no wall of flavor text on legacy when you complete a quest, or you have a quest in progress.

In the examples, I tried to stick with the image size that's currently on the default Kumos quests, but I understand where you're coming from regarding immersion. I'm really looking forward to the finalized quest layout so that people can start customizing it to suit their preferences!