demo.css

* {
    padding: 0;
    margin: 0;
    list-style: none;
}

body {
    max-width: 940px;
    margin: 0 auto;
    font: 14px/1.5 "Helvetica Neue", Helvetica, Arial, "Microsoft Yahei", "Hiragino Sans GB", "Heiti SC", "WenQuanYi Micro Hei", sans-serif;
    background: #222;
}

.about {
    padding: 10px;
    color: #fff;
    font-size: 14px;
    background: #1D1F21;
}

.item {
    margin: 10px 10px 30px 10px;
    background: #333;
}

.item .tit {
    overflow: hidden;
    padding: 5px 10px;
    font-size: 16px;
    color: #fff;
    background: #24a990;
}

.item .tit span {
    display: inline-block;
    padding: 3px 10px;
    margin: 0 5px;
    font-size: 12px;
    -webkit-border-radius: 5px;
    border-radius: 5px;
    background: #298675;
    cursor: pointer;
}

.item .tit span.on {
    background: #0e5044;
}

.item .content {
    padding: 10px;
    font-size: 14px;
    color: #fff;
}

.item .attr {
    border: 1px solid #24a990;
}

.item .attr li {
    padding-left: 10px;
    border-top: 1px solid #24a990;
    line-height: 38px;
}

.item .attr li h3 {
    font-weight: normal;
    font-size: 16px;
    color: #A84C60;
}

.item .query {
    margin-left: 60px;
    color: #D8932B;
}

.item .query li {
    line-height: 28px;
    border-top: none;
}

textarea {
    overflow-y: scroll;
    display: block;
    width: 100%;
    min-height: 100px;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
    padding: 10px;
    resize: none;
    border: none;
    color: #fff;
    background: #222;
}

textarea:focus {
    outline: none;
}

.demo {
    width: 250px;
    height: 250px;
    background: #108423;
}

.demo div {
    min-width: 40px;
    min-height: 40px;
    background: #f1d722;
    text-align: center;
    line-height: 50px;
    color: #222;
}

.demo div+div {
    line-height: 23px;
    background: #f95656;
}

.demo div+div+div {
    line-height: 30px;
    background: #5fc383;
}