React.DOM.div({className: 'classname'},React.DOM.div({className: 'classname'},<custom-tag>React.DOM.div({className: 'classname'},React.DOM.div({className: 'classname'},))</custom-tag>)))
React.DOM.div({dangerouslySetInnerHTML={{__html: '<custom-tag/>'}}},
React.DOM.div({className: 'classname'}, ... }