style.css

body {
    text-align: center;
    padding: 10px 18%;
}
p {
    user-select: none;
}
button {
    margin: 8px 0;
    padding: 4px 14px;
    background-color: #F8F8F8;
    border: 1px solid #888;
    border-radius: 3px;
    transition-duration: 0.3s;
    transition-timing-function: ease;
    cursor: pointer;
}
button:hover {
    background-color: #DDD;
}
button:active {
    background-color: #BBB;
}
#content {
    width: 100% !important;
    height: 200px;
    font-family: "Microsoft Yahei", Helvetica, Arial, sans-serif;
}
input {
    height: 20px;
    margin: 2px 5px;
}
input, textarea {
    border: 1px solid #888;
    background-color: #FFF;
    border-radius: 3px;
    font-size: 16px;
    transition: background-color 0.3s ease,
                border-color 0.3s ease;
}
input:hover, textarea:hover {
    background-color: #DDD;
}
input:focus, textarea:focus {
    outline: none;
    border: 1px solid #444;
}