[UI] Implement base font types, font color, background colors, border-radius, drop-shadow

[LaurenMcM749]

Implement standardized colors and font site-wide, according to the Product Figma file.

The designs are more far-reaching than this introduction ticket. However, it will be useful to explore them, become comfortable with the colors and fonts used, and other aspects of the design at a base level.

The goal of this ticket is to implement at a site-wide level a base font color, background color, and font styles. You should do this in one file (I believe a CSS file), not page by page.

Requirements

• Default Font Color: 1C1C33 (Note: When you explore the Figma, you will see this color is called "purple-2/700" in the color menu. It is part of the language in our brand, but you don't need to worry about the Figma naming in code! Just wanted to flag this as an FYI.)
• Default Border-Radius: 20 px
• Color of Nav bar, cards, and inputs: F7F7FA (Called "neutrals-2/50" in Libraries panel)
• H1/H2/H3 Default Font: Poppins
• H4/H5/p Default Font: Bitter
• Nav bar, cards, inputs: All have default drop shadow