Reference multiple words in css -

i have wordpress page , see 1 of items style has id of wpb_text_column wpb_content_element textboxtest. how can reference in css since has spaces between words?

it not have 1 class multiple classes. reference in css

.wpb_text_column.wpb_content_element.textboxtest {           /* css code */ } 

ids unique , div can contain one.