Angular material stepper header lines styling

In production environment those reflect active attributes don't exist, so I came up with this solution based on the index of the elements. I just give a class to the mat-horizontal-stepper element with the index of the active step: last-edited-step-0, last-edited-step-1, last-edited-step-2. Then I created this mixins:

@mixin styleStepLine($index) {
    .mat-horizontal-stepper-header {
        &+.mat-stepper-horizontal-line:nth-child(#{$index}) {
            height: 2px;
            background-image: linear-gradient(to right, #00b495, #00aeea);
        }
    }
}

@mixin styleEditedStepIcon($index) {
    .mat-horizontal-stepper-header:nth-child(#{$index}) {
        .mat-step-icon:not(.mat-step-icon-selected) {
            background-color: map-get($colors, 'light-green');
        }
    }
}

@mixin styleUnEditedStepIcon($index) {
    .mat-horizontal-stepper-header:nth-child(#{$index}) {
        .mat-step-icon:not(.mat-step-icon-selected) {
            background-color: #e8e8e8;
        }
    }
}

.last-edited-step-1 {
    @include styleStepLine(2);
    @include styleEditedStepIcon(1);
    @include styleUnEditedStepIcon(3);
}

.last-edited-step-2 {
    @include styleStepLine(2);
    @include styleStepLine(4);
    @include styleEditedStepIcon(1);
    @include styleEditedStepIcon(3);
}

I am late to this thread, thinking this may be helpful for someone. I have the same requirement except for the icon colors I tried every solution suggested but nothing was working as expected. I tried the below solution which is working fine for me-

DEMO

@mixin styleStepLine($index) {
	.mat-horizontal-stepper-header {
		&+.mat-stepper-horizontal-line:nth-child(#{$index}) {
			height: 2px;
			background-image: linear-gradient(to right, #00b495, #00aeea);
		}
	}
}

@mixin styleEditedStepIcon($index) {
	.mat-horizontal-stepper-header:nth-child(#{$index}) {
		.mat-step-icon:not(.mat-step-icon-selected) {
			background-color: red;
		}
	}
}

@mixin styleUnEditedStepIcon($index) {
	.mat-horizontal-stepper-header:nth-child(#{$index}) {
		.mat-step-icon:not(.mat-step-icon-selected) {
			background-color: #e8e8e8;
		}
	}
}

.last-edited-step-1 {
	@include styleStepLine(2);
}

.last-edited-step-2 {
	@include styleStepLine(2);
	@include styleStepLine(4);
}

.mat-stepper-label-position-bottom .mat-horizontal-stepper-header:not(:first-child)::before,
.mat-stepper-label-position-bottom .mat-horizontal-stepper-header:not(:last-child)::after,
[dir=rtl] .mat-stepper-label-position-bottom .mat-horizontal-stepper-header:not(:first-child)::after,
[dir=rtl] .mat-stepper-label-position-bottom .mat-horizontal-stepper-header:not(:last-child)::before {
	width: 0!important;
}

.mat-step-header .mat-step-header-ripple {
	display: none;
}

.mat-step-header.cdk-keyboard-focused,
.mat-step-header.cdk-program-focused,
.mat-step-header:hover {
	background-color: #fff;
}

.mat-stepper-label-position-bottom .mat-horizontal-stepper-header {
	padding: 8px 0 8px 0 !important;
	width: 35px !important;
}

.mat-stepper-label-position-bottom .mat-stepper-horizontal-line {
	top: 20px !important;
}
<mat-horizontal-stepper linear #stepper ngClass="{{ 'last-edited-step-' + stepper.selectedIndex }}" labelPosition="bottom">
  <mat-step [stepControl]="firstFormGroup" errorMessage="Name is required.">
    <form [formGroup]="firstFormGroup">
      <ng-template matStepLabel>h1</ng-template>
      <mat-form-field>
        <input matInput placeholder="Last name, First name" formControlName="firstCtrl" required>
      </mat-form-field>
      <div>
        <button mat-button matStepperNext>Next</button>
      </div>
        <mat-form-field appearance="outline">
    <mat-label>Outline form field</mat-label>
    <input matInput placeholder="Placeholder">
    <mat-hint>Hint</mat-hint>
  </mat-form-field>
    </form>
  </mat-step>
  <mat-step [stepControl]="secondFormGroup" errorMessage="Address is required.">
    <form [formGroup]="secondFormGroup">
      <ng-template matStepLabel>h2</ng-template>
      <mat-form-field>
        <input matInput placeholder="Address" formControlName="secondCtrl" required>
      </mat-form-field>
      <div>
        <button mat-button matStepperPrevious>Back</button>
        <button mat-button matStepperNext>Next</button>
      </div>
    </form>
  </mat-step>
  <mat-step>
    <ng-template matStepLabel>Done</ng-template>
    You are now done.
    <div>
      <button mat-button matStepperPrevious>Back</button>
      <button mat-button (click)="stepper.reset()">Reset</button>
    </div>
  </mat-step>
</mat-horizontal-stepper>


Here's my solution, inspired on the one proposed by @dazzed.

In the HTML, I'm giving a class to the mat-horizontal-stepper of 'last-edited-step-'last-edited-step-' + stepper.selectedIndex.

In terms of CSS, I'm dynamically generating classes with SASS for loops, so looping ($i) from .last-edited-step-last-edited-step-1 up to .last-edited-step-last-edited-step-42 (42 as an example, that is meant to be the number of steps, of course). Then inside each of them, I'm looping again ($j) between the first and the nth line and then assigning the properties (in my case, a green border colour).

stepper.component.html

    <mat-horizontal-stepper #stepper [linear]="true" class="{{ 'last-edited-step-' + stepper.selectedIndex }}">

        <mat-step>
        </mat-step>

        <mat-step>
        </mat-step>

        <mat-step>
        </mat-step>

    </mat-horizontal-stepper>

stepper.component.sass

/deep/ mat-horizontal-stepper
  @for $i from 1 through 42
    &.last-edited-step-#{$i}
     @for $j from 1 through $i
        .mat-stepper-horizontal-line:nth-of-type(#{$j})
          border-color: #00c190 !important

Using that, together with styling a few other elements (the circles, icons, line proportions) you can get something like this:

Result with coloured lines between steps

Tags:

Angular

Angular Material

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