Server.pm: New DuckDuckGo homepage has a new CSS file.

The new CSS file is static.css (or sxxx.css in production). We need to slurp this in, too.

This fixes https://github.com/duckduckgo/p5-app-duckpan/issues/90. The file has mixed tabs and spaces so the format looks wonky. I fixed that in https://github.com/duckduckgo/p5-app-duckpan/pull/91.