Hi Andrii,
thanks a lot you have such a great and quick support!!
I have changed it in this way:
.page-template-page_full-width-php #content,
.page-template-page_full-width-no-header-php #content,
.page-template-page_portfolio-four-column-php #content,
.page-template-page_portfolio-three-column-php #content,
.page-template-page_portfolio-two-column-php #content,
.page-template-page_portfolio-one-column-php #content,
.page-template-single-php #content,
.page-template-single-project-php #content {
width: 100%;
padding: 0;
}
other page template was an old leftover
This works now for my page where I have displayed the grid: http://www.buehnenwerkstatt.at/buehnenwerkstatt-projekte/
but when selecting a single project it will appear again only over 2/3 of the page: http://www.buehnenwerkstatt.at/essential_grid/drifting-through-farbflusskoerper/
what do you think?
thanks christoph