review

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    color: #737373;
    background: url('back.jpg') center / cover;
    margin: 0;
}

button {
    padding: 10px 20px;
    font-size: 18px;
    color: white;
    background: #4990E2;
    font-weight: bold;
    font-family: inherit;
    line-height: 1;
    border: none;
    text-transform: uppercase;
    border-radius: 4px;
    box-shadow: 0px 10px 15px -5px rgba(100, 100, 100, .35);
    margin: 10px;
}

button:hover {
    background: #1a84ff;
}

button:focus {
    outline: none;
    background: #1f63b2;
}

img {
    width: 140px;
    margin: auto;
    padding: 0;
    display: block;
}

.login {
    display: flex;
    flex-direction: column;
    height: 100vh;
    align-items: center;
}

.login h1 {
    color: #4990E2;
    font-size: 34px;
    margin: 30px 0;
    text-shadow: 1px 2px 8px rgba(100, 100, 100, .3);
}

.login img {
    margin-top: 20px;
}

.login form {
    width: 300px;
    background: white;
    padding: 20px;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    border-radius: 4px;
    box-shadow: 0px 4px 40px rgba(100, 100, 100, .35);
}

.login label {
    width: 100%;
    display: block;
    font-size: 18px;
}

.login input {
    width: 100%;
    display: block;
    border: none;
    font-family: inherit;
    color: inherit;
    font-size: 19px;
    line-height: 1.4;
    border-bottom: 1px solid #4990E2;
    margin-bottom: 20px;
}

.login input:focus {
    outline: none;
}

.login footer {
    margin-top: auto;
    margin-bottom: 30px;
    font-size: 18px;
    background: white;
    padding: 4px 10px;
    border-radius: 4px;
    box-shadow: 0px 4px 40px rgba(100, 100, 100, .35);
}

.chat {
    text-align: center;
}

.chat header {
    display: inline-block;
    max-width: 200px;
    vertical-align: top;
    margin-right: 50px;
    margin-top: 20px;
}

.chat img {
    margin-bottom: 20px;
}

.chat h2 {
    color: #4990E2;
    font-size: 28px;
    margin: 10px 0;
    text-shadow: 1px 2px 8px rgba(100, 100, 100, .3);
}

.chat main {
    display: inline-block;
    vertical-align: top;
    text-align: left;
    max-width: 600px;
    margin: 40px 10px;
}

.chat form {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin: 0px 0 70px;
}

.chat textarea:focus {
    outline: none;
}

.chat textarea {
    width: 100% !important;
    margin-bottom: 20px;
    border: none;
    font-family: inherit;
    color: inherit;
    font-size: 18px;
    line-height: 1.2;
    padding: 8px 16px;
    border-radius: 4px;
    box-shadow: 0px 4px 40px rgba(100, 100, 100, .35);
}

::-webkit-input-placeholder {
    color: #ccc;
}

::-moz-placeholder {
    color: #ccc;
}

::-ms-input-placeholder {
    color: #ccc;
}

.chat span>button {
    margin-right: 5px;
}

history {
    display: block;
}

message {
    display: block;
    font-size: 18px;
    background: white;
    padding: 8px 16px;
    margin: 15px 0;
    border-radius: 4px;
    box-shadow: 0px 4px 40px rgba(100, 100, 100, .35);
}

author {
    display: inline;
    font-weight: bold;
}

author:empty {
    display: none;
}

author::after {
    content: ': ';
}