[ENHANCEMENT] provide better visibility for key information

**Is your feature request related to a problem? Please describe.**
A few things that I noticed looking at the feature detail page:
- The Baseline status of a feature is not immediately obvious on the feature detail page. It's shown mixed with the browser cards
- The explainer text uses the full width of the page, which makes it hard to read.
- The wpt.fyi and caniuse buttons push the name of the feature down
- The date picker is disconnected from the charts
- The divider from the top line info is the header that says "Web platform test scores", but it has the same font-size as the explainer text, so there is no clear separation
- The percentage changes in the browser cards have no indication of what change they are representing and having two percentages next to each other takes focus away from the current shipping score.
- The browser cards are not lining up, Chrome for Android is shown under Chrome for desktop, but Firefox for Android is under Edge, making it harder to scan.
- When a WPT score is missing the placeholder is a grey blob, which looks like a bug.

**Describe the solution you'd like**
- Baseline status should be right below the name of the feature
- Explainer text [should be set to 66ch](https://en.wikipedia.org/wiki/Line_length#Electronic_text) max width.
- The wpt.fyi and caniuse buttons should be to the right of the feature name or at the bottom of the top line section.
- The date picker should be moved to right above the charts
- The page should be broken up into sections that can have their own boxes: top line, detailed browser info, charts.
- The headers should be clearly indicated as headers, bold and larger font-size
- The percentage change in the browser cards should be removed to put focus on the headline number
- The browser boxes should line up with desktop on top and mobile at the bottom or possibly putting the mobile scores on another tab like with the charts.
- If there is no WPT score to show, there should be an icon indicating that with a tool tip to explain it.