Web programmer for a one-time task

A web programmer with extensive experience is sought.

Your knowledge and skills:
Experience in integrating ready-made solutions,
Experience in integrating (writing) own solutions/modules,
PHP,
MySQL,
JavaScript/JQuery,
Sass, HTML5, CSS3, Bootstrap (sometimes for small sub-folding)
Bitrix, ModX and Prestoshop.


Task:
A little improvement of the site on one of the popular CMS.

Portfolio is a must!!!!
Studios, agencies and collectives are not interesting!!!!