router-outlet takes additional space on the page (Angular 2)

Question

Here is an interesting question that I was kind of ignoring, until now. It seems like Angular2 renders the content inside directive tags. But, for router-outlet, it happens to be like a sibling.

My first question is: why? Just out of interest.

I would not worry about it much, but it is now actually causing a problem in my app. I have two nested outlets and for some inexplicable reason, the child one is taking 15px height on the page and does not matter what I do, I can't get rid of it. (see screenshot)

Is what I described really the case or I am simply doing something wrong? Also, I have no idea at this point how to approach this, searched all over, didn't find anything.

Thanks for your help.

UPDATE here is my less file:

@import "../../node_modules/bootstrap-less/bootstrap/bootstrap";
@import "../../node_modules/font-awesome/less/font-awesome";
@icon-font-path: "./bootstrap/fonts/";
@fa-font-path: "./font-awesome/fonts";
@import "rrm.less";

html, body {
  height: 100% !important;
}
body {
  padding-top: 80px;
}
.load-container {
  background: rgba(0, 0, 0, 0.5);
  width: 100%;
  height: 100%;
  .loaing {
    position: fixed;
    left: 50%;
    top: 35%;
    z-index: 1000;
    height: 31px;
    width: 31px;
  }
}
.top-navbar {
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  background-color: #FFFFFF;
  height: 80px;
  &.floating {
    .box-shadow(0 1px 3px rgba(0,0,0,.25));
  }
  .navbar-brand {
    height: auto;
    img {
      height: 60px;
    }
  }
  .navbar-nav > li > a {
    font-size: 20px;
    padding-top: 15px;
    padding-bottom: 15px;
    line-height: 50px;
  }
}
.rrm-container {
  height:100%;
  display: table;
  width: 100%;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  padding-left: 0px;
  padding-right: 0px;
  .rrm-wrapper {
    height: 100%;
    display: table-row;
    .left-menu {
      float: none;
      display: table-cell;
      .box-shadow(0 1px 3px rgba(0,0,0,.25));
      ul {
        li {
          border: none;
          background-color: transparent;
        }
      }
    }
    .content {
      float: none;
      display: table-cell;
    }
  }
}

And here is the box model that FF computes:

Answer 1

In response to your first question of why place the component template as a sibling of the <router-outlet> and not inside of it, there are a couple of github threads which shed some light.

https://github.com/angular/angular/issues/8529#issuecomment-217718704 https://github.com/angular/angular/issues/4679

Most relevant:

The original reason for this behavior was to enable animation of elements between views during which time both source and destination components would need to be active