Restyle alert panels

[ericronne]

When time allows, here's some mods for the various alert blocks. I'm happy to attack myself, but first need someone such as @cwaring to show me where the controls are buried.

• [ ] Narrow the left strip to 4 pixels wide for all
• [ ] 0.5px letter spacing for the all-caps headers
• [ ] TIP
  • [ ] Left strip #696d78
  • [ ] BG #f2f4f7
  • [ ] Text #34373f
• [ ] INFO (may not be req'd)
  • [ ] Left strip #0e74aa
  • [ ] BG #e6F6ff
  • [ ] Text #34373f
• [ ] WARNING
  • [ ] Left strip #e7c000
  • [ ] BG #fff7d2
  • [ ] Text #34373F
• [ ] DANGER
  • [ ] Left strip #a93e3e
  • [ ] BG #ffe6e6
  • [ ] Text #a93e3e