SOURCE

var $messages = $('.messages-content'),
    d, h, m,
    i = 0;

$(window).load(function() {
  $messages.mCustomScrollbar();
  setTimeout(function() {
    fakeMessage();
  }, 100);
});

function updateScrollbar() {
  $messages.mCustomScrollbar("update").mCustomScrollbar('scrollTo', 'bottom', {
    scrollInertia: 10,
    timeout: 0
  });
}

function setDate(){
  d = new Date()
  if (m != d.getMinutes()) {
    m = d.getMinutes();
    $('<div class="timestamp">' + d.getHours() + ':' + m + '</div>').appendTo($('.message:last'));
  }
}

function insertMessage() {
  msg = $('.message-input').val();
  if ($.trim(msg) == '') {
    return false;
  }
  $('<div class="message message-personal">' + msg + '</div>').appendTo($('.mCSB_container')).addClass('new');
  setDate();
  $('.message-input').val(null);
  updateScrollbar();
  setTimeout(function() {
    fakeMessage();
  }, 1000 + (Math.random() * 20) * 100);
}

$('.message-submit').click(function() {
  insertMessage();
});

$(window).on('keydown', function(e) {
  if (e.which == 13) {
    insertMessage();
    return false;
  }
})

var Fake = [
  'Hi there, I\'m Fabio and you?',
  'Nice to meet you',
  'How are you?',
  'Not too bad, thanks',
  'What do you do?',
  'That\'s awesome',
  'Codepen is a nice place to stay',
  'I think you\'re a nice person',
  'Why do you think that?',
  'Can you explain?',
  'Anyway I\'ve gotta go now',
  'It was a pleasure chat with you',
  'Time to make a new codepen',
  'Bye',
  ':)'
]

function fakeMessage() {
  if ($('.message-input').val() != '') {
    return false;
  }
  $('<div class="message loading new"><figure class="avatar"><img src="http://s3-us-west-2.amazonaws.com/s.cdpn.io/156381/profile/profile-80_4.jpg" /></figure><span></span></div>').appendTo($('.mCSB_container'));
  updateScrollbar();

  setTimeout(function() {
    $('.message.loading').remove();
    $('<div class="message new"><figure class="avatar"><img src="http://s3-us-west-2.amazonaws.com/s.cdpn.io/156381/profile/profile-80_4.jpg" /></figure>' + Fake[i] + '</div>').appendTo($('.mCSB_container')).addClass('new');
    setDate();
    updateScrollbar();
    i++;
  }, 1000 + (Math.random() * 20) * 100);

}

<!--

Follow me on
Dribbble: https://dribbble.com/supahfunk
Twitter: https://twitter.com/supahfunk
Codepen: http://codepen.io/supah/

It's just a concept, a fake chat to design a new daily UI for direct messaging.
Hope you like it :)

-->

<div class="chat">
  <div class="chat-title">
    <h1>Fabio Ottaviani</h1>
    <h2>Supah</h2>
    <figure class="avatar">
      <img src="http://s3-us-west-2.amazonaws.com/s.cdpn.io/156381/profile/profile-80_4.jpg" /></figure>
  </div>
  <div class="messages">
    <div class="messages-content"></div>
  </div>
  <div class="message-box">
    <textarea type="text" class="message-input" placeholder="Type message..."></textarea>
    <button type="submit" class="message-submit">Send</button>
  </div>

</div>
<div class="bg"></div>

/*--------------------
Mixins
--------------------*/
@mixin center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

@mixin ball {
  @include center;
  content: '';
  display: block;
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: rgba(255, 255, 255, .5);
  z-index: 2;
  margin-top: 4px;
  animation: ball .45s cubic-bezier(0, 0, 0.15, 1) alternate infinite;
}


/*--------------------
Body
--------------------*/
*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  background: linear-gradient(135deg, #044f48, #2a7561);
  background-size: cover;
  font-family: 'Open Sans', sans-serif;
  font-size: 12px;
  line-height: 1.3;
  overflow: hidden;
}

.bg {
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  z-index: 1;
  background: url('https://images.unsplash.com/photo-1451186859696-371d9477be93?crop=entropy&fit=crop&fm=jpg&h=975&ixjsv=2.1.0&ixlib=rb-0.3.5&q=80&w=1925') no-repeat 0 0;
  filter: blur(80px);
  transform: scale(1.2);
}


/*--------------------
Chat
--------------------*/
.chat {
  @include center;
  width: 300px;
  height: 80vh;
  max-height: 500px;
  z-index: 2;
  overflow: hidden;
  box-shadow: 0 5px 30px rgba(0, 0, 0, .2);
  background: rgba(0, 0, 0, .5);
  border-radius: 20px;
  display: flex;
  justify-content: space-between;
  flex-direction: column;
}


/*--------------------
Chat Title
--------------------*/
.chat-title {
  flex: 0 1 45px;
  position: relative;
  z-index: 2;
  background: rgba(0, 0, 0, 0.2);
  color: #fff;
  text-transform: uppercase;
  text-align: left;
  padding: 10px 10px 10px 50px;
  
  h1, h2 {
    font-weight: normal;
    font-size: 10px;
    margin: 0;
    padding: 0;
  }
  
  h2 {
    color: rgba(255, 255, 255, .5);
    font-size: 8px;
    letter-spacing: 1px;
  }
  
  .avatar {
    position: absolute;
    z-index: 1;
    top: 8px;
    left: 9px;
    border-radius: 30px;
    width: 30px;
    height: 30px;
    overflow: hidden;
    margin: 0;
    padding: 0;
    border: 2px solid rgba(255, 255, 255, 0.24);
    
    img {
      width: 100%;
      height: auto;
    }
  }
}


/*--------------------
Messages
--------------------*/
.messages {
  flex: 1 1 auto;
  color: rgba(255, 255, 255, .5);
  overflow: hidden;
  position: relative;
  width: 100%;
  
  & .messages-content {
    position: absolute;
    top: 0;
    left: 0;
    height: 101%;
    width: 100%;
  }

  
  .message {
    clear: both;
    float: left;
    padding: 6px 10px 7px;
    border-radius: 10px 10px 10px 0;
    background: rgba(0, 0, 0, .3);
    margin: 8px 0;
    font-size: 11px;
    line-height: 1.4;
    margin-left: 35px;
    position: relative;
    text-shadow: 0 1px 1px rgba(0, 0, 0, .2);
    
    .timestamp {
      position: absolute;
      bottom: -15px;
      font-size: 9px;
      color: rgba(255, 255, 255, .3);
    }
    
    &::before {
      content: '';
      position: absolute;
      bottom: -6px;
      border-top: 6px solid rgba(0, 0, 0, .3);
      left: 0;
      border-right: 7px solid transparent;
    }
    
    .avatar {
      position: absolute;
      z-index: 1;
      bottom: -15px;
      left: -35px;
      border-radius: 30px;
      width: 30px;
      height: 30px;
      overflow: hidden;
      margin: 0;
      padding: 0;
      border: 2px solid rgba(255, 255, 255, 0.24);

      img {
        width: 100%;
        height: auto;
      }
    }
    
    &.message-personal {
      float: right;
      color: #fff;
      text-align: right;
      background: linear-gradient(120deg, #248A52, #257287);
      border-radius: 10px 10px 0 10px;
      
      &::before {
        left: auto;
        right: 0;
        border-right: none;
        border-left: 5px solid transparent;
        border-top: 4px solid #257287;
        bottom: -4px;
      }
    }
    
    &:last-child {
      margin-bottom: 30px;
    }
    
    &.new {
      transform: scale(0);
      transform-origin: 0 0;
      animation: bounce 500ms linear both;
    }
    
    &.loading {

      &::before {
        @include ball;
        border: none;
        animation-delay: .15s;
      }

      & span {
        display: block;
        font-size: 0;
        width: 20px;
        height: 10px;
        position: relative;

        &::before {
          @include ball;
          margin-left: -7px;
        }

        &::after {
          @include ball;
          margin-left: 7px;
          animation-delay: .3s;
        }
      }
    }
    
  }
}


/*--------------------
Message Box
--------------------*/
.message-box {
  flex: 0 1 40px;
  width: 100%;
  background: rgba(0, 0, 0, 0.3);
  padding: 10px;
  position: relative;
  
  & .message-input {
    background: none;
    border: none;
    outline: none!important;
    resize: none;
    color: rgba(255, 255, 255, .7);
    font-size: 11px;
    height: 17px;
    margin: 0;
    padding-right: 20px;
    width: 265px;
  }
  
  textarea:focus:-webkit-placeholder{
      color: transparent;
  }
  
  & .message-submit {
    position: absolute;
    z-index: 1;
    top: 9px;
    right: 10px;
    color: #fff;
    border: none;
    background: #248A52;
    font-size: 10px;
    text-transform: uppercase;
    line-height: 1;
    padding: 6px 10px; 
    border-radius: 10px;
    outline: none!important;
    transition: background .2s ease;
    
    &:hover {
      background: #1D7745;
    }
  }
}


/*--------------------
Custom Srollbar
--------------------*/
.mCSB_scrollTools {
  margin: 1px -3px 1px 0;
  opacity: 0;
}

.mCSB_inside > .mCSB_container {
  margin-right: 0px;
  padding: 0 10px;
}

.mCSB_scrollTools .mCSB_dragger .mCSB_dragger_bar {
  background-color: rgba(0, 0, 0, 0.5)!important;
}


/*--------------------
Bounce
--------------------*/
@keyframes bounce { 
  0% { transform: matrix3d(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  4.7% { transform: matrix3d(0.45, 0, 0, 0, 0, 0.45, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  9.41% { transform: matrix3d(0.883, 0, 0, 0, 0, 0.883, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  14.11% { transform: matrix3d(1.141, 0, 0, 0, 0, 1.141, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  18.72% { transform: matrix3d(1.212, 0, 0, 0, 0, 1.212, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  24.32% { transform: matrix3d(1.151, 0, 0, 0, 0, 1.151, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  29.93% { transform: matrix3d(1.048, 0, 0, 0, 0, 1.048, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  35.54% { transform: matrix3d(0.979, 0, 0, 0, 0, 0.979, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  41.04% { transform: matrix3d(0.961, 0, 0, 0, 0, 0.961, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  52.15% { transform: matrix3d(0.991, 0, 0, 0, 0, 0.991, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  63.26% { transform: matrix3d(1.007, 0, 0, 0, 0, 1.007, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  85.49% { transform: matrix3d(0.999, 0, 0, 0, 0, 0.999, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); }
  100% { transform: matrix3d(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1); } 
}


@keyframes ball { 
  from {
    transform: translateY(0) scaleY(.8);
  }
  to {
    transform: translateY(-10px);
  }
}