make html valid

- encode invalid characters in URL (pipe and space)
- add alt attribute to image
- move iframe's styling attributes to css (100% is an invalid value for the width attribute, and the frameborder attribute is deprecated)

also harmonize spacing in css, and shorten the line with the bootstrap link.
typo
Change bootstrap title.
Merge branch 'waldir-patch-3' into gh-pages

* waldir-patch-3:
  Change bootstrap title.
  typo
  make html valid