body, ul, li {
    margin: 0;
    padding: 0;
    list-style: none;
}
.wrapper {
    margin:100px auto 0;
    width: 230px;
    height: 230px;
    border-radius: 40px;
    background: #111;
    overflow: hidden; /* 解决margin塌陷问题 */
}
.clock {
    position: relative;
    margin: 15px 0 0 15px;
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: #fff;
}
.num-box {
    position: relative;
    width: 100%;
    height: 200px;
    border-radius: 50%;
}
.num {
    position: absolute;
    top: 0;
    left: 50%;
    margin-left: -15px;
    width: 30px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    transform-origin: 15px 100px;
}
.num span {
    display: inline-block;
    font-size: 20px;
    font-weight: 600px;
}
.radio {
    position: absolute;
    left: 50%;
    top: 50%;
    margin-left: -5px;
    margin-top: -5px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: #000;
}
.hour {
    position: absolute;
    left: 98px;
    top: 30px;
    width: 4px;
    height: 70px;
    border-radius: 2px;
    background: #111;
    transform-origin: center bottom;
    transform: rotate(30deg);
}
.min {
    position: absolute;
    left: 98px;
    top: 10px;
    width: 4px;
    height: 90px;
    border-radius: 2px;
    background: #111;
    transform-origin: center bottom;
    transform: rotate(60deg);
}
.sec {
    position: absolute;
    left: 99px;
    top: 10px;
    width: 2px;
    height: 100px;
    border-radius: 1px;
    background: red;
    transform-origin: center 90px;
}