* {
  margin: 0;
  border: 0;
  padding: 0;
}

a {
  text-decoration: none;
  color: rgb(121, 121, 121);
}

a:hover {
  color: black;
}

#div-content {
  /* margin-top: 155px; */
  width: 1440px;

  /* position: relative;
  top: -205px; */
  /* z-index: -1; */

  /* border: 2px solid red; */
}

/* TODO: figure a feasible way of h* */
h1 {
  font-size: 18px;
  font-weight: normal;
  font-family: Arial;
}

h2 {
  font-size: 16px;
  font-weight: normal;
  font-family: Arial;
}

h3 {
  font-size: 16px;
  font-weight: normal;
  font-family: Arial;
}

h4 {
  font-size: 16px;
  font-weight: normal;
  font-family: Arial;
}

.h1-title {
  margin-top: 30px;
  text-align: center;
}

.h2-rel {
  margin-top: 20px;
  margin-left: 200px;
}

.h2-title {
  margin-top: 15px;
  text-align: center;
}

.h3-rel {
  margin-top: 10px;
  margin-left: 240px;
}

.h4-rel {
  margin-top: 10px;
  margin-left: 280px;
}

/* TODO: figure whether width: 1440px is necessary */
#iframe-footer {
  margin-top: 30px;
  width: 1440px;
  height: 60px;
}

#iframe-header {
  /* position: absolute; */
  /* top: 0px; */
  width: 100%;
  /* width: 1440px; */
  height: 330px;
  /* TODO：figure why z-index not working */
  /* z-index: 2; */
  /* TODO: figure */
  /* pointer-events: none; */

  /* TODO: figure */
  /* overflow-x: hidden; */
  /* overflow-y: hidden; */
}

li {
  width: auto;
}

.li-rel {
  /* excluding list type space */
  margin-left: 340px;
  font-size: 16px;
  font-family: Arial;
  line-height: 1.5;
}

p {
  text-align: justify;
}

ul {
  list-style-type: none;
}

.ul-rel {
  list-style-type: decimal;
  margin-right: 200px;
}

video {
  display: block;
}