* {
  padding: 0;
  margin: 0;
}

a {
  text-decoration: none;
  color: #ccc;
}

ul,
ol {
  list-style: none;
}

.focus {
  position: relative;
  width: 100%;
  /* 需要设置高度之后绝对子元素绝对定位才能使用百分比 */
  height: 430px;
  margin: 20px auto;
  overflow: hidden;
}

.focus li img {
  max-width: 100%;
  max-height: 100%;
  /*max-height: 430px;*/
}

.arrow-left,
.arrow-right {
  display: none;
  position: absolute;
  top: 50%;
  width: 38px;
  height: 38px;
  line-height: 38px;
  text-align: center;
  color: #fff;
  font-weight: 700;
  cursor: pointer;
  background-color: rgba(0, 0, 0, .3);
  transform: translateY(-50%);
  transition: all 1s linear;
  z-index: 2;
}

.arrow-left:hover,
.arrow-right:hover {
  color: #ccc;
}

.arrow-left {
  left: 0;
  border-radius: 0 15px 15px 0;
}

.arrow-right {
  right: 0;
  border-radius: 15px 0 0 15px;
}

.focus ul {
  position: absolute;
  top: 0;
  left: 0;
  width: 600%;
}

.focus ul li {
  float: left;
}

.focus ol {
  position: absolute;
  bottom: 16px;
  left: 50%;
  /*  移动自身宽度的50% */
  transform: translateX(-50%);
}

.focus ol li {
  float: left;
  margin-right: 10px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  cursor: pointer;
  border: 3px solid rgba(255, 255, 255, .5);
}

.focus ol li.cur_point {
  background-color: #fff;
  border-color: #ffffff;
}