- simplify template
- use flexboxes
- simplify javascript code
- remove some obsolete code adjusting a background-position when using steppers buttons
- add comments and remove old code
No more javascript to change css properties
Remove a number of useless tables
Try to stop positioning elements with absolute, but use flex-boxes instead
Adds comment to pad template, and move popups and chatbox inside editorcontainerbox (so absolute positioning is straightforward)
Make the design more consistent: always use base color, font-family and font-size. USe relative font size if necessary (.9rem instead of 11px for example)
Remove two columns in the popups, just use one column
Remove css meant to support old browser (like -webkit-box-shadow, -moz-box-shadow). Those css rules are quite common now, and If we want to support very old browser, we should use clean-css or other tools to add them automatically
* Add a new file `lists_and_indents.css` to hold the common CSS.
* Remove the corresponding CSS from `iframe_editor.css`, replacing it with
an `@import` of the new file.
* Remove the list/indent code from `timeslider.css`, which was _unlike_ the
corresponding editor CSS code, again replacing it with an `@import` of the
new file.
