Change mat-select-arrow and mat-select-underline when focused

Question

So far I've tried lots of different things, such as:

/deep/ .mat-select:focus .mat-select-trigger .mat-select-arrow {
    color: #63961C;
}

/deep/ .mat-select:focus .mat-select-trigger .mat-select-underline {
    background-color: #63961C;
}

Or :

/deep/ .mat-select.mat-focused .mat-select-trigger .mat-select-arrow {
    color: #63961C;
}

/deep/ .mat-select.mat-focused .mat-select-trigger .mat-select-underline {
    background-color: #63961C;
}

to change that little arrow next to a select, and the underline.

For example, I did

/deep/ .mat-input-container.mat-focused .mat-input-underline {
    background-color: #63961C;
}

for the underline of an Input, and it worked fine (it becomes green when focusing). (yes /deep/ works fine for this project, though it's deprecated now if I remember well)

I managed to change it "all the time", but what I want, is to have it green only on focus, and keep it grey if not focused.

Answer 1

Avoid using /deep/ (read this documentation). You should use ViewEncapsulation.

In your ts file, set ViewEncapsulation to None:

import { ViewEncapsulation } from '@angular/core';

@Component({
  ...
  encapsulation: ViewEncapsulation.None
})

.. and add the following classes to your component's css file:

/* to change arrow when focused */
.mat-select:focus:not(.mat-select-disabled).mat-primary .mat-select-arrow {
    color: #63961C;
}

/* to change underline when focused */
.mat-select:focus:not(.mat-select-disabled).mat-primary .mat-select-underline {
    background-color: #63961C;
}

/* to change plceholder text when focused */
.mat-select:focus:not(.mat-select-disabled).mat-primary .mat-select-trigger {
    color: #63961C;
}

/* to change selected item color in the select list */
.mat-primary .mat-option.mat-selected:not(.mat-option-disabled) {
    color: #63961C;
}

Link to working demo.

To make the css shorter,

.mat-select:focus:not(.mat-select-disabled).mat-primary 
.mat-select-arrow , .mat-select-underline , .mat-select-trigger 
{
    color: #63961C;
}

/* to change selected item color in the select list */
.mat-primary .mat-option.mat-selected:not(.mat-option-disabled) {
    color: #63961C;
}