ugly links in homepage footer

Created by: sfkeller

1a. There are some broken SVG images in footer of homepage. 1b. And homepage seems to have problems fitting page to screen (there's a vertical scroll bar appearing at my 16:8 laptop screen 1600x900). 2. While correcting this, pls. add social media metadata for Twitter card and Facebook image: See https://giswiki.hsr.ch/Best_Practices_for_Web_Maps#Metadata_for_Social_Media