lite-youtube custom element

View isolated demos:

• lite-youtube-embed - Basic
• lite-youtube-embed - Progressively enhanced
• lite-youtube-embed - Custom poster image
• lite-youtube-embed - With parameters
• lite-youtube-embed - Multiple embeds on same page
• lite-youtube-embed - Custom poster size
• lite-youtube-embed - Fallback poster
• lite-youtube-embed - Force load API
• lite-youtube-embed - Global config
• lite-youtube-embed - No WebP
• lite-youtube-embed - Show title
• lite-youtube-embed - Playlists
• normal youtube embed