Guest_Book/style.css

body {
    background-color: #01252b;
    color: white;
    font-family: monospace;
}

h1 span {
    display: inline-block;
    line-height: 36px;
}

#container {
    position: absolute;
    max-width: 1000px;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    width: 84%;
    height: auto;
    margin: auto;
    padding: 8% 4%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

#hi {
    display: block;
    text-align: center;
}

#rotate {
    -ms-transition: 0.4s ease-in-out;
    -webkit-transition: 0.4s ease-in-out;
    transition: 0.4s ease-in-out;
}

#rotate:hover, #rotate:active {
    -ms-transform: rotate(180deg); /* IE 9 */
    -webkit-transform: rotate(180deg); /* Chrome, Safari, Opera */
    transform: rotate(180deg);
}

.guestbook {
    display: block;
    width: 100%;
    height: 100%;
    min-height: 168px;
    background: darkslategray;
    margin: 20px auto;
    box-shadow: 10px 10px 5px #162222;
    border-radius: 10px;
    overflow: auto;
}

.guestbook h2 {
    text-align: center;
}

.guestbook table {
    margin: 0 8px;
    border: none;
}

.guestbook table td {
    padding: 8px;
    text-align: left;
    vertical-align: top;
    white-space: preserve;
}

.author {
    font-weight: bold;
    width: 110px;
}

.guestbook-form {
    display: flex;
    flex-direction: row;
    width: 100%;
    text-align: center;
    align-items: center;
    margin: 10px auto;
    box-shadow: 10px 10px 5px #162222;
}

.guestbook-form input {
    display: block;
    float: left;
    width: 90%;
    resize: none;
    padding: 10px;
    background: darkslategray;
    color: #ffffff;
    border: none;
    border-radius: 6px 0 0 6px;
}

.guestbook-form #name {
    float: left;
    width: 120px;
    border-radius: 6px;
    margin-right: 8px;
    font-weight: bold;
}

.guestbook-form #entryText {
    width: 80%;
}

.guestbook-form button {
    float: right;
    width: 10%;
    min-width: 72px;
    height: auto;
    padding: 10px;
    border-radius: 0 6px 6px 0;
    background: #2e6971;;
    color: #ffffff;
    border: none;
    font-weight: bold;
    cursor: pointer;
}

.time {
    display: inline;
    opacity: 0;
    color: #61959d;
    font-size: small;
    transition: opacity 0.5s linear;
}

tr:hover .time {
    opacity: 1;
}

#error-message {
    opacity: 0;
    color: red;
    display: block;
    text-align: center;
    margin: 10px 0;
    transition: opacity 0.5s linear;
}

#error-message.visible {
    opacity: 1;
}

@media (max-width: 640px) {

    .guestbook-form {
        display: block;
        box-shadow: none;
        width: 100%;
        padding: 0;
        align-items: center;
    }

    .guestbook-form input {
        border-radius: 6px;
        margin-bottom: 12px;
        box-shadow: 10px 10px 5px #162222;
    }

    .guestbook-form #name {
        width: calc(100% - 20px);
        margin-right: 0;
    }

    .guestbook-form #entryText {
        width: calc(100% - 20px);
    }

    .guestbook-form button {
        width: 100%;
        border-radius: 6px;
        box-shadow: 10px 10px 5px #162222;
    }

    .time {
        display: none;
    }
}