html code generated by my jinja templates generally look half garbage because of indents and whitespace all over the place. I just learned about these pesky Whitespace Control characters that can get rid of the whitespace added from templating.
You can also strip whitespace in templates by hand. If you add a minus sign (-) to the start or end of a block (e.g. a For tag), a comment, or a variable expression, the whitespaces before or after that block will be removed:
{% for item in seq -%} {{ item }} {%- endfor %}