Actually the Democrats also got more total votes than the Republicans in both the Senate and the House of Representatives. It was the peculiarities of the U.S. electoral system, particularly the extensive 'gerrymandering' of House districts by Republican state governments, that gave the Republicans their seat leads. Trump had and has a significant core of very loyal supporters while the Democratic support for Clinton in the past election  was, at best, lukewarm and that cost her what was an extremely close election..  Now, the anti-Trump movement is equally dedicated as Trump supporters. The next election will certainly be lively.