merge #extend with parent style and make one class name - css

Question

I'm trying to merge the style into one class but its showing an error. Look at the example below.
%banner-style{
banner {
padding: 140px 0 210px;
background: url(https://im2.ezgif.com/tmp/ezgif-2-92c6382d82ba.jpg) top center/cover no-repeat;
&.row {
margin: 0;
}
.main-heading {
font-size: 40px;
letter-spacing: -1px;
font-weight: 600;
padding-right: 20px;
sup {
font-size: 10px;
vertical-align: super;
}
}
}
}
And I want it to merge with the parent class .parent
.parent{
color: red;
&_#extend %banner-style;
}
using & to merge into one class name. but showing error unless i do this
.parent{
color: red;
&_{#extend %banner-style};
}
Which is same as if I remove &_.
I wanted .parent_banner {...} but instead got .parent_ banner{...};
Does anyone know how I can accomplish this?

Answer 1

You are getting exactly what is supposed to happen. Extend does not "merge" classes, it extends another class/placeholder into a new selector's styles.
What that means is if I write:
%banner-style {
background: black;
}
.parent {
#extend %banner-style;
}
.other-selector {
#extend %banner-style;
color: red;
}
The css I get will be
.parent {
background: black;
}
.other-selector {
color: red;
background: black;
}
So you are getting expected results. If you'd like to make this "work" the way you want, you can just change your code to:
%banner-style {
padding: 140px 0 210px;
background: url(https://im2.ezgif.com/tmp/ezgif-2-92c6382d82ba.jpg) top center/cover no-repeat;
&.row {
margin: 0;
}
.main-heading {
font-size: 40px;
letter-spacing: -1px;
font-weight: 600;
padding-right: 20px;
sup {
font-size: 10px;
vertical-align: super;
}
}
}
.parent{
color: red;
&_banner {
#extend %banner-style;
};
}
Note: I took out the banner block because it seems you don't want that (and banner isn't a normal html element).