Snazzy Info Window is a plugin for customizable info windows using the Google Maps JavaScript API. Open sourced by the people that created Snazzy Maps.
Features
Responsive sizing : The info window will size properly for a variety of screen and map sizes
Custom styling : Customize the border radius, shadow, background color, border, and much more. Supports SCSS styling.
Dynamic content : Supports dynamic content after initialization with proper resizing
Multiple placements : Place the info window to the top, bottom, right, or left of the marker.