title: Ant Design: How are they changing color on run time and so quick?
body: <p>I am using Ant Design in a React project. Ant provides styles in less which provides a way to customize theme and then build the code (less to css) but on their website (<a href="https://ant.design/docs/react/introduce" rel="nofollow noreferrer">https://ant.design/docs/react/introduce</a>) at the bottom they have a color picker which let you change the <code>@primary-color</code> instantly in over all places. No api call is being made and I tried to compile Ant Design less file i.e. <code>node_modules/antd/dist/antd.less</code> in browser but it takes few seconds (5-10) to compile. 
  I also tried to do this using server side compilation by sending variables in POST request and then inserting returned css in DOM but that is not good. </p>
  
  <p>I need help to achieve this functionality. Thanks in advance.
  <a href="https://i.stack.imgur.com/F3Sxk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/F3Sxk.png" alt="enter image description here"></a></p>