A Pen by Derek Wheelden.

index.html

<div class="main-container">
  <h1>User Listing Panel</h1>
  <p>It&rsquo;s over there on the right. It&rsquo;s responsive too.</p>
</div>
<div class="user-container">
  <i class="fa fa-users"></i>
  <h3>Connected</h3>
<ul class="users">
  <li class="is-active">
    <div class="users__user--status"><i class="fa fa-circle"></i></div>
    <div class="users__user--name">Sherriff B.</div>
    <div class="users__user--interactions">
      <i class="fa fa-envelope"></i>
      <i class="fa fa-comment"></i>
    </div>
  </li>
  <li class="is-active">
    <div class="users__user--status"><i class="fa fa-circle"></i></div>
    <div class="users__user--name">Waco K.</div>
    <div class="users__user--interactions">
      <i class="fa fa-envelope"></i>
      <i class="fa fa-comment"></i>
    </div>
  </li>
  <li class="is-current-user is-idle">
    <div class="users__user--status"><i class="fa fa-circle"></i></div>
    <div class="users__user--name">Hedley L.</div>
    <div class="users__user--interactions">
      <i class="fa fa-envelope"></i>
      <i class="fa fa-comment"></i>
    </div>
  </li>
  <li class="is-active">
    <div class="users__user--status"><i class="fa fa-circle"></i></div>
    <div class="users__user--name">Lili V.S.</div>
    <div class="users__user--interactions">
      <i class="fa fa-envelope"></i>
      <i class="fa fa-comment"></i>
    </div>
  </li>
  <li class="is-offline">
    <div class="users__user--status"><i class="fa fa-circle"></i></div>
    <div class="users__user--name">William J.L.P.</div>
    <div class="users__user--interactions">
      <i class="fa fa-envelope"></i>
      <i class="fa fa-comment"></i>
    </div>
  </li>
</ul>  
</div>

style.scss

@import "compass";
$base-color: hsl(200, 100, 40);
$breakpoint : 'max-width: 1300px';

.main-container {
  width: 70%;
  height: 100%;
  background: $base-color;
  float: left;
}

.user-container {
  width: 30%;
  height: 100%;
  background: desaturate(darken($base-color, 15%), 40%);
  color: white;
  float: right;
  overflow-y: auto;
  cursor: default;
  
  > i { padding: 0.5em; visibility: hidden; }
}

@media ($breakpoint) {
  .main-container {
    width: 100%;
    float: none;
  }
  
  .user-container {
    position: absolute;
    top: 0;
    right: 0;
    width: 25em;
    float: none;
    transition: transform 0.5s;
    transform: translateX(calc(100% - 2em));
    &:hover { transform: translateX(0); }
    
    > i { visibility: visible; }
  }
}

.users {
  margin: 0;
  padding: 0;
  list-style: none;
  line-height: 3;
  
  li {
    padding: 0 3em;
    @extend .cf;
  }
  
  li:nth-child(odd) {
    background: desaturate(darken($base-color, 10%), 40%);
  }
  
  li.is-current-user {
    color: lighten($base-color, 30%);
  }
  
  li.is-active {
    .users__user--status i {
      color: hsl(100, 80, 60);
    }
  }
  li.is-idle {
    .users__user--status i {
      color: hsl(50, 80, 60);
    }
  }
  li.is-offline {
    .users__user--status i {
      color: hsl(0, 80, 60);
    }
    .users__user--name { opacity: 0.5; }
    .users__user--interactions i.fa-comment {
      opacity: 0.2;
      cursor: default;
      &:hover:after { display: none; }
    }
  }
}

.users__user--status {
  padding-right: 1em;
  font-size: 0.7em;
  line-height: 4.3;
  float: left;
}

.users__user--name {
  float: left; 
}

.users__user--interactions {
  float: right;
  
  i {
    position: relative;
    margin-left: 0.5em;
    padding: 0.5em;
    cursor: pointer;
  }
  
  li.is-current-user & { visibility: hidden; }
}

i.fa-envelope:hover:after, i.fa-comment:hover:after {
  content: 'Send Email';
  display: inline-block;
  position: absolute;
  top: 50%;
  right: 100%;
  padding: 0.5em;
  border-radius: 0.25em;
  background: white;
  font-size: 0.7em;
  font-family: 'Lato';
  font-weight: 700;
  text-transform: lowercase;
  white-space: nowrap;
  color: darken($base-color, 20%);
  z-index: 100;
  transform: translateY(-50%);
}

i.fa-comment:hover:after {
  content: 'Private Message';
}

i.disabled {
  opacity: 0.3;
  cursor: default;
  
  &:hover:after { display: none; }
}

/** PAGE STYLES **/
@import url(http://fonts.googleapis.com/css?family=Lato:300,700|Oswald);
@import url(//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css);

* { box-sizing: border-box; }

html, body { width: 100%; height: 100%; }

html { font-size: 62.5%; }

body {
  font-family: 'Lato', sans-serif;
  font-size: 2em;
  line-height: 1.5;
  font-weight: 300;
  overflow-x: hidden;
  -webkit-backface-visibility: hidden;
}

p { color: white; text-align: center; }

h1 {
  margin: 0;
  padding: 0.75em 0 0;
  font-family: 'Oswald', sans-serif;
  font-size: 4em;
  text-transform: uppercase;
  text-align: center;
  color: white;
}

h3 {
  margin: 0 0 0.5em;
  font-size: 1.5em;
  font-weight: 300;
  color: lighten($base-color, 20%);
  
  .user-container & { padding: 1em 2em 0; }
}

.cf:before,
.cf:after {
    content: " "; /* 1 */
    display: table; /* 2 */
}

.cf:after {
    clear: both;
}

.cf {
    *zoom: 1;
}

User-Listing.markdown

User Listing

A little design for a web chat app I'm working on.

A Pen by Derek Wheelden on CodePen.

License.