#menu_slide {}
#slide_droite{}

#portamento_container {float:left; position:relative;} /* take the positioning of the sidebar, and become the start point for the sidebar positioning */
#portamento_container #menu_slide {float:none; position:absolute;} /* no need to float anymore, become absolutely positoned */
#portamento_container #menu_slide.fixed {position:fixed;} /* if the panel is sliding, it needs position:fixed */

#portamento_container #slide_droite {float:none; position:absolute;} /* no need to float anymore, become absolutely positoned */
#portamento_container #slide_droite.fixed {position:fixed;} /* if the panel is sliding, it needs position:fixed */