/* 容器样式 */
#container {
    background-color: blue;
    margin: 0 auto;
    width: 400px;
    padding: 20px;
    display: flex;
    justify-content: space-around;
    align-items: center;
}

/* 正方形和圆形的通用样式 */
.square, .circle {
    width: 100px;
    height: 100px;
    display: block;
}

/* 圆形样式 */
.circle {
    border-radius: 50%;
}

/* 单独的块颜色 */
#blockRed {
    background-color: red;
    position: relative;
}

#blockYellow {
    background-color: yellow;
    position: relative;
}