/* 챌린지 1 */
.box {
  border: 50px solid red;
  width: 200px;
  padding: 50px;
  margin-bottom: 20px;
}

.green {
  border-color: green;
  /* display: none; -> 사라지면서 아래 공간 땡김*/
  /* visibility: hidden; -> 사라지면서 공간은 남음*/
}

.blue {
  border-color: #0e00cf;
}

/* 챌린지 2 */

hr {
  border: none;
  height: 1px;
  background-color: #ccc;
  margin: 20px 0;
}

h1 {
  color: #9b59b6;
}

h1:first-child {
  text-align: center;
}

h1::before {
  content: "Topic: ";
}

p {
  font-size: 16px;
  font-family: Verdana;
  font-style: italic;
}

p::first-letter {
  font-size: 200%;
  color: #2980b9;
}

.challenge2 {
  background-color: #fff;
  background-image: linear-gradient(
      90deg,
      transparent 79px,
      #abced4 79px,
      #abced4 81px,
      transparent 81px
    ),
    linear-gradient(#eee 0.1em, transparent 0.1em);
  background-size: 100% 1.2em;
  padding-left: 10%;
}

.sub-header {
  color: #2980b9;
}