Design update

[RobinDaugherty]

Goals:

• Make the content semantic, to support those with screen readers.
• Cleaner. Embrace flat design and remove the text shadows, box shadows, etc.
• More obvious connection between stack navigation and the entire right side of the page. All of the items on the right are within the context of the selected stack item, but that's not obvious in the current design.
• Continuity with the existing design. This should feel at home for a longtime user of Better Errors.

To Do

• Add aria-role to the navigation and segmented control.
• Change the segmented control to black and white.
• Add title to icons in the call stack so that "A" can be understood.
• Some cleanup for the "small" screen version (mostly for mobile).
• Support for "dark mode" UI using media queries.
• Add some kind of explanation that this is Better Errors, maybe link to the project page for help.
• Make the console input area more obvious.

Screenshots

For comparison:

[Geesu]

The input text area was more obvious in the original design, maybe add some shadows so it is obvious?