v2.7.2

• Refine mobile menu toggle functionality.
• Prevent nav item from growing taller on focus. #59
• Fix overflow clipping for featured records.
• Consolidate title and image links for a11y.
• Remove default visited link color with poor contrast.
• Move away from tab styling for secondary nav.
• Simplify single record displays, use empty alts for associated images.
• Remove modernizr and outdated polyfills.
• Provide aria labels for nav landmarks.
• Refine search filter styling.