#site-body {
  background-color: #fff;
}

/*
 $ 课程明细信息 $
 */
.course-detail {
  padding: 0 0 32px;
}
.course-detail::after {
  display: table;
  content: '';
  clear: both;
}
.course-detail__pic {
  position: relative;
  overflow: hidden;
  float: left;
  width: 540px;
  height: 308px;
  background: #fafafa;
}
.course-detail__pic > img {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
  max-width: 100%;
  max-height: 100%;
}
.course-detail__content {
  float: right;
  width: 570px;
}
.course-detail__title {
  margin: 8px 0 24px;
  line-height: 1.5;
  font-size: 24px;
}
.course-detail__info {
  font-size: 16px;
}
.course-detail__info__item {
  height: 32px;
  line-height: 32px;
}
.course-detail__info__item .icon {
  margin-right: 8px;
}
.course-detail__info__item > .key {
  color: #999;
}
.course-detail__info__item > .key::after {
  display: inline;
  margin: 0 4px;
  content: ':'
}
.course-detail__info__item > .value {
  color: #333;
}
.course-detail__info__item > strong.value {
  font-weight: 700;
  font-size: 18px;
  color: #E74C4C;
}

.course-detail__actions {
  margin-top: 32px;
}
.course-detail__actions > .button {
  width: 180px;
  padding: 0;
}
.course-detail__actions > .button > img {
  vertical-align: top;
  position: relative;
  top: 16px;
  margin-right: 4px;
}


/*
 $ 课程明细页面布局 $
 */
 .course-cols {
  width: 100%;
  padding: 32px 0 32px;
  background: #F7F7F8;
}

.course-main {
  width: 700px;
}

.course-sub {
  width: 460px;
}


/* 课程简介，讲师简介 tab */
.course-summary,
.course-teacher {
  padding: 16px 32px;
  font-size: 16px;
  line-height: 30px;
  color: #333;
}

/* 课件下载 tab */
.course-download {
  padding: 16px 32px;
}
.course-download-list {
  overflow: hidden;
  font-size: 16px;
}
.course-download-list__item {
  position: relative;
  overflow: hidden;
  line-height: 1.5;
  padding: 16px 100px 16px 0;
}
.course-download-list__item::after {
  display: table;
  content: '';
  clear: both;
}
.course-download-list__item__title {
  float: left;
  width: 100%;
}
.course-download-list__item__link {
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;
  margin: auto;
  float: right;
  width: 72px;
  height: 28px;
  padding: 0;
}

/* 课程章节 tab */
.course-sections {
  padding: 16px 32px;
}

.course-sub .box__hd .tabs,
.course-main .box__hd .tabs {
  margin: 0 0 0 -19px;
}
.course-sub .box__hd .tabs .tabs__item,
.course-main .box__hd .tabs .tabs__item {
  margin: 0 0 0 -1px;
  padding: 0 32px;
  border-left: 1px solid #E7EDF4;
  border-right: 1px solid #E7EDF4;
}
.course-sub .box__hd .tabs .tabs__item--active,
.course-main .box__hd .tabs .tabs__item--active {
  border-top-width: 2px;
  border-top-style: solid;
  border-bottom-width: 0;
  background-color: #fff;
}
.course-sub .box__hd .tabs .tabs__item:first-child,
.course-main .box__hd .tabs .tabs__item:first-child {
  border-left: none;
}
.course-sub .box__hd .tabs .tabs__item:last-child,
.course-main .box__hd .tabs .tabs__item:last-child {
  border-right: none;
}


/*
 $ 课程章节列表 $
 */
.outline {
  padding-bottom: 24px;
}
.course-item {
  position: relative;
  margin: 12px 0;
  padding: 0;
  line-height: 24px;
  transition: all .16s;
}
.course-item--level-1 {
  margin-left: 0;
}
.course-item--level-2 {
  margin-left: 24px;
}
.course-item--level-3 {
  margin-left: 48px;
}
.course-item--level-4 {
  margin-left: 72px;
}
.course-item__icon {
  box-sizing: border-box;
  overflow: hidden;
  position: absolute;
  top: 1px;
  right: auto;
  bottom: auto;
  left: 0;
  width: 16px;
  height: 16px;
  border-radius: 3px;
  cursor: pointer;
  background: #fff;
}
.course-item__icon::before {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
  overflow: hidden;
  content: '';
  transition: all .16s;
  width: 8px;
  height: 8px;
  border-top: 1px solid #999;
  border-right: 1px solid #999;
  transform: rotate(45deg);
}
.course-item__icon--on::before {
  top: -1px;
  transform: rotate(135deg);
}
.course-item--leaf .course-item__icon {
  top: 2px;
  width: 20px;
  height: 20px;
  border-width: 2px;
  border-style: solid;
  border-radius: 10px;
  opacity: .3;
}
.course-item--leaf:hover .course-item__icon {
  opacity: 1;
}
.outline > .course-item > .course-item__icon {
  top: 3px;
}
.outline > .course-item--leaf > .course-item__icon {
  top: 1px;
}
.course-item--leaf .course-item__icon::before {
  left: 2px;
  width: 0;
  height: 0;
  border-top: 4px solid transparent !important;
  border-right: 0;
  border-bottom: 4px solid transparent !important;
  border-left-width: 4px;
  border-left-style: solid;
  background: none;
  transform: none;
}
.course-item__content {
  padding-left: 24px;
}
.course-item--leaf .course-item__content {
  padding-left: 28px;
}
.course-item__title {
  font-size: 14px;
  line-height: 1.5;
  color: #111;
  cursor: pointer;
}
.course-item--played .course-item__title {
  color: #999;
}
.course-item--empty.course-item--empty .course-item__title {
  cursor: not-allowed;
  color: #aaa;
}
.course-item--empty .course-item__icon,
.course-item--empty .course-item__icon::before {
  border-color: #aaa;
}
.course-item--empty:hover .course-item__icon {
  cursor: not-allowed;
  opacity: .3;
}