Use justify-content: flex-end and to have vertical scrollbar

.session-textchat {  height: 320px;  background: #fff;  display: -webkit-flex;  display: flex;  -webkit-align-items: flex-end;  align-items: flex-end;  -webkit-justify-content: space-between;  justify-content: space-between;  -webkit-flex-direction: column;  flex-direction: column;}.session-textchat .past-messages {  width: 100%;  max-width: 980px;  margin: 0 auto;  height: 83.92%;  overflow-y: auto;  padding: 30px 0 0;  display: -webkit-flex;  display: flex;  -webkit-align-items: flex-end;  align-items: flex-end;  -webkit-justify-content: flex-end;  justify-content: flex-end;  -webkit-flex-direction: column;  flex-direction: column;}.session-textchat .past-messages .receiver,.session-textchat .past-messages .sender {  width: 100%;  min-height: 47px;  margin: 0 0 20px;  display: -webkit-flex;  display: flex;  -webkit-flex-direction: row;  flex-direction: row;}.session-textchat .past-messages .receiver .message,.session-textchat .past-messages .sender .message {  position: relative;  padding: 17px;  -moz-border-radius: 4px;  -webkit-border-radius: 4px;  border-radius: 4px;}.session-textchat .past-messages .receiver {  text-align: left;  -webkit-justify-content: flex-start;  justify-content: flex-start;}.session-textchat .past-messages .receiver .message {  background: #f4f4f4;  color: #535353;}.session-textchat .past-messages .sender {  text-align: right;  -webkit-justify-content: flex-end;  justify-content: flex-end;}.session-textchat .past-messages .sender .message {  background: url('../img/rgbapng/0050ff26.png');  background: rgba(0, 80, 255, 0.15);  color: #0050ff;}

<div class="session-textchat"><div class="past-messages"><div class="receiver"><span class="message">            Good afternoon David. Welcome to your appointment! How are you today?</span></div><div class="sender"><span class="message">            Hello doctor. I feel terrible to be honest.</span></div><div class="receiver"><span class="message">            I can see from your notes that you've been having some ear ache - can you tell me a bit more about your symptoms?</span></div><div class="sender"><span class="message">            Hello doctor. I feel terrible to be honest.</span></div><div class="receiver"><span class="message">            I can see from your notes that you've been having some ear ache - can you tell me a bit more about your symptoms?</span></div></div></div>