Improves popup css

This PR:

- deactivates the resize of popup (when we drag the header)
- makes the popup of tools (draw, measure, featuretree, importXXX) usable on small screen

Test [here](http://mf-geoadmin3.dev.bgdi.ch/dev_popupcss/prod/?X=88500.00&Y=611000.00&zoom=1&lang=fr&topic=ech&bgLayer=ch.swisstopo.pixelkarte-farbe&catalogNodes=457&layers_opacity=0.75)