Диалоги как у вконтакте. Как прилепить блок ввода сообщения к низу блока чата?

.block-flex-div { 
  display: flex; 
  width: 100%; 
  justify-content: space-between; 
  box-sizing: border-box; 
} 
 
.block-line-flex { 
  display: flex; 
  padding: 8px; 
  height: auto; 
  font-size: 14px; 
  width: 100%; 
  color: #666; 
  font-weight: 500; 
  text-align: left; 
  box-sizing: border-box; 
} 
 
.block-column-flex { 
  flex: 1; 
} 
 
.block-flex-div.dialogs-block { 
  height: 100%; 
} 
 
.block-column-flex.dialogs-user-list { 
  flex: 1 1 13%; 
  min-width: 150px; 
  white-space: nowrap; 
  overflow: hidden; 
  overflow-y: auto; 
  color: #999; 
  font-size: 16px; 
  border: 1px solid #efefef; 
} 
 
.block-column-flex .dialogs-user-info { 
  padding: 10px; 
  border-top: 1px solid #efefef; 
  text-align: left 
} 
 
.block-column-flex .dialogs-user-info:first-child { 
  border-top: 0px solid #efefef; 
} 
 
.block-column-flex .dialogs-user-info:last-child { 
  border-bottom: 1px solid #efefef; 
} 
 
.block-column-flex .dialogs-user-info .dialogs-user-photo { 
  flex: 1 1 20%; 
  padding: 5px; 
} 
 
.block-column-flex .dialogs-user-info .dialogs-user-name { 
  flex: 2 1 80%; 
  padding: 5px; 
} 
 
.block-column-flex.dialogs-user-chat { 
  flex: 2 1 80%; 
  border-top: 1px solid #efefef; 
  border-right: 1px solid #efefef; 
  border-bottom: 1px solid #efefef; 
  display: flex; 
  flex-direction: column; 
} 
 
.block-line-flex.dialogs-user-chat-body-wrap { 
  flex-grow: 1; 
} 
 
.block-line-flex.dialogs-user-chat-input { 
  background: #fafbfc; 
  max-height: 70px; 
  border-top: 1px solid #efefef 
} 
 
.block-column-flex.chat-text-input { 
  flex: 1 1 80%; 
  padding: 5px; 
} 
 
.block-column-flex.chat-text-input #text { 
  box-sizing: border-box; 
  width: 100%; 
  padding: 8px 10px; 
} 
 
.block-column-flex.chat-input-send-bottom { 
  flex: 2 1 20%; 
  padding: 5px; 
}

<div class="block-flex-div dialogs-block"> 
  <div class="block-column-flex dialogs-user-list"> 
    <div class="block-line-flex dialogs-user-info"> 
      <div class="block-column-flex dialogs-user-photo"> 
        <img src="http://cliparting.com/wp-content/uploads/2016/05/Smiley-face-crazy-face-clip-art-smiley-eyes-clip-art-vector-clip-art.jpg" width="50" class="img-circle img-responsive vknotify-comment-avatar"> 
      </div> 
      <div class="block-column-flex dialogs-user-name"> 
        Имя 
      </div> 
    </div> 
    <div class="block-line-flex dialogs-user-info"> 
      <div class="block-column-flex dialogs-user-photo"> 
        <img src="http://cliparting.com/wp-content/uploads/2016/05/Smiley-face-crazy-face-clip-art-smiley-eyes-clip-art-vector-clip-art.jpg" width="50" class="img-circle img-responsive vknotify-comment-avatar"> 
      </div> 
      <div class="block-column-flex dialogs-user-name"> 
        Имя 
      </div> 
    </div> 
    <div class="block-line-flex dialogs-user-info"> 
      <div class="block-column-flex dialogs-user-photo"> 
        <img src="http://cliparting.com/wp-content/uploads/2016/05/Smiley-face-crazy-face-clip-art-smiley-eyes-clip-art-vector-clip-art.jpg" width="50" class="img-circle img-responsive vknotify-comment-avatar"> 
      </div> 
      <div class="block-column-flex dialogs-user-name"> 
        Имя 
      </div> 
    </div> 
    <div class="block-line-flex dialogs-user-info"> 
      <div class="block-column-flex dialogs-user-photo"> 
        <img src="http://cliparting.com/wp-content/uploads/2016/05/Smiley-face-crazy-face-clip-art-smiley-eyes-clip-art-vector-clip-art.jpg" width="50" class="img-circle img-responsive vknotify-comment-avatar"> 
      </div> 
      <div class="block-column-flex dialogs-user-name"> 
        Имя 
      </div> 
    </div> 
    <div class="block-line-flex dialogs-user-info"> 
      <div class="block-column-flex dialogs-user-photo"> 
        <img src="http://cliparting.com/wp-content/uploads/2016/05/Smiley-face-crazy-face-clip-art-smiley-eyes-clip-art-vector-clip-art.jpg" width="50" class="img-circle img-responsive vknotify-comment-avatar"> 
      </div> 
      <div class="block-column-flex dialogs-user-name"> 
        Имя 
      </div> 
    </div> 
  </div> 
  <div class="block-column-flex dialogs-user-chat"> 
    <div class="block-line-flex dialogs-user-chat-body-wrap"> 
      чат 
    </div> 
    <div class="block-line-flex dialogs-user-chat-input"> 
      <div class="block-column-flex chat-text-input"> 
        <input type="text" id="text" name="text" value="" placeholder="Текст ответа"> 
      </div> 
      <div class="block-column-flex chat-input-send-bottom"> 
        <button type="button" class="btn btn-success">Отправить</button> 
      </div> 
    </div> 
  </div> 
</div>