Minor dashboard updates

BugFix Merge Request

Related Issue

Didn't create one 😅

Description of Bug and Fix

Updated the dashboard styles to reflect the wireframe designs in Figma. This included:

1. Typeface sizing/weight/color
2. Updating navTab styling
3. Updating padding in the dashboard markup
4. Adding explainer text / empty states

Motivation and Context

Gotta get this MVP-ready

Related Tasks

• Need to create conditionals that determine what text is displayed, depending upon if it's within the Current, Available or Past/Completed sections of the dashboard.

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