style.css

html {
    margin: 0px;
    padding: 1.5%;
    width: 97%;
}

.row {
    width: 97%;
}

.outer-wrapper {
    border: 1px solid #cccccc;
    box-shadow: 0 0 10px #cccccc;
    float: left;
    height: 400px;
    margin: 1.5%;
    padding: 1.5%;
    width: 19.6%;
}

.outer-wrapper:first-child {
    margin-left: 0px;
}

.outer-wrapper:last-child {
    margin-right: 0px;
}

.outer-wrapper:before,
.outer-wrapper:after {
    display: none;
}

.chapters {
    background-color: lemonchiffon;
    margin: 0px;
    padding: 10px;
    text-align: center;
}

.form-element {
    display: block;
    width: 100%;
}

.form-element input,
.form-element span {
    margin: 5px;
    padding: 5px;
}

.form-element input[type="submit"] {
    text-transform: uppercase;
    width: 90%;
}

.form-element input[type="text"] {
    width: 80%;
}

table {
    width: 100%;
}

img, iframe {
    width: 100%;
}

h1 {
    display: inline-block;
}

#message,
#login-button {
    display: inline-block;
    cursor: pointer;
    float: right;
    margin: 5px;
    padding: 5px;
    text-transform: uppercase;
}

#message {
    text-transform: none;
}

#signin-form {
    display: none;
    position: fixed;
    width: 100vw;
    height: 100vh;
    background-color: rgba(0, 0, 0, 0.7);
    left: 0px;
    top: 0px;
}

#signin-form form {
    position: fixed;
    width: 30vw;
    margin-left: 35%;
    margin-top: 30vh;
    background-color: #fff;
    border: 3px solid #666;
    box-shadow: 0 0 10px #cccccc;
    padding: 10px;
}

#signin-form .input-wrapper label {
    display: inline-block;
    width: 25%;
    float: left;
    margin: 5px;
    padding: 5px;
    text-align: right;
}

#signin-form .input-wrapper input {
    display: inline-block;
    width: 60%;
    float: right;
}

#signin-form .button-wrapper {
    text-align: right;
    float: right;
}

#signin-form #username,
#signin-form #userpassword,
#signin-form .signin-button,
#signin-form .cancel-button {
    margin: 5px;
    padding: 5px;
}

#signin-form .signin-button,
#signin-form .cancel-button {
    cursor: pointer;
}

@media screen and (max-width: 400px) {
    .outer-wrapper {
        width: 94%;
    }

    .outer-wrapper:first-child {
        margin-left: 1.5%;
    }

    .outer-wrapper:last-child {
        margin-right: 1.5%;
    }
}

@media screen and (max-width: 768px) {
    .outer-wrapper {
        width: 43%;
    }

    .outer-wrapper:first-child {
        margin-left: 1.5%;
    }

    .outer-wrapper:last-child {
        margin-right: 1.5%;
    }
}

@media screen and (max-width: 1024px) {
    .outer-wrapper {
        width: 26.6666666667%;
    }

    .outer-wrapper:first-child {
        margin-left: 1.5%;
    }

    .outer-wrapper:last-child {
        margin-right: 1.5%;
    }
}