CSS Wildcard Selectors
Sometimes you need a 'wildcard' selector for your class or id. This can be necessary in bootstrap or other frameworks when working with several column widths. Instead of doing something like the following:
.content-blocks > .col-md-3 > .panel{
    position: relative;
}
.content-blocks > .col-md-3 > .panel > .panel-footer{
    position: absolute;
    bottom: 0;
    width: 100%;
}
.content-blocks > .col-md-4 > .panel{
    position: relative;
}
.content-blocks > .col-md-4 > .panel > .panel-footer{
    position: absolute;
    bottom: 0;
    width: 100%;
}
.content-blocks > .col-md-6 > .panel{
    position: relative;
}
.content-blocks > .col-md-6 > .panel > .panel-footer{
    position: absolute;
    bottom: 0;
    width: 100%;
}
You can simplify it by using a wildcard that anything with that path with any column width needs to have certain styles. This is great for buttons and such things. Above, we account for only 3 different situations, of which there are MANY more when you consider col-xs, col-sm, col-md, col-lg, and the different widths within each of those. What if we could apply a style to ALL columns? We can with the wildcard selector:
.content-blocks > div[class^='col-'] > .panel{
    position: relative;
}
.content-blocks > div[class^='col-'] > .panel > .panel-footer{
    position: absolute;
    bottom: 0;
    width: 100%;
}
div[class^='col-']  states that 'anything that starts with col-'. Other options are div[class*='col-']  'anything that contains' and div[class$='-6'] 'anything that ends with'.
 

CSS Selectors List / CSS Wildcard Table

Selector Example Example description CSS
[attribute] [target] Selects all elements with a target attribute 2
[attribute=value] [target=_blank] Selects all elements with target=”_blank” 2
[attribute~=value] [title~=nickfever] Selects all elements with a title attribute containing the word “nickfever” 2
[attribute|=value] [lang|=en] Selects all elements with a lang attribute value starting with “en” 2
[attribute^=value] a[src^="https"] Selects every <a> element whose src attribute value begins with “https” 3
[attribute$=value] a[src$=".pdf"] Selects every <a> element whose src attribute value ends with “.pdf” 3
[attribute*=value] a[src*="nickfever"] Selects every <a> element whose src attribute value contains the substring “nickfever” 3
table from surfingsuccess.com