I was doing same before learning ReactJS last year. Now i am creating from scratch my collection of custom elements and i use react-flexgrid for responsive layouts. Big libraries like Bootstrap and Semantic are dead for me. I want to have total control of my elements and avoid overriding css and tons of globals (Bootstrap i am staring at you). Give it a shot. This approach scales really well for big projects and you keep unwanted code outside of your bundle.
If you still need some minimum things from Bootstrap for example and you use webpack you can use bootstrap-loader and narrow down the imported stuff but i highly suggest to drop Bootstrap and create your own elements by using postcss goodies.