title: How to change the underline color of md-input-container in angular4?
body: <p>I have been reading the docs for this (<a href="https://material.angular.io/components/input/overview" rel="noreferrer">https://material.angular.io/components/input/overview</a>) There is a section that says how to change the color of the line at the bottom of the md-input-container. But it is not clear to me what an attribute is nor is there a code example to refer to. It says the underline color can be changed using the color attribute of the md-input-container. In addition what I mean by underline is the animated underline that expands out as visible in the provided link. Could somebody explain more clearly what the attribute of md-input-container is, or provide some code. I have tried adding a directive called color, changing the color of md-input-container in css, amongst other things and I am not succeeding at this. If somebody could explain/show some code that demonstrates this, that would be very helpful. Thanks!</p>
  
  <p>Here is some code, which I feel should work, based on the wording of that text. But it does not.</p>
  
  <pre><code>  &lt;md-input-container
      color="yellow"
      class="input-half-width"&gt;
      &lt;input
        [(ngModel)]="driftInfo.title"
        name="title"
        mdInput
        placeholder="Ange rubrik"
      &gt;
    &lt;/md-input-container&gt;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/dsz8W.png" rel="noreferrer"><img src="https://i.stack.imgur.com/dsz8W.png" alt="enter image description here"></a></p>