#app {
  width: 100%;
  height: 100vh;
  background-color: #fff;

  display: flex;
  align-items: center;
  justify-content: center;

  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;

  text-align: center;
  transition: background-color 0.2s ease;
}

#app.active {
  background-color: red;
  color: #fff;
  font-weight: 500;

  cursor: wait;
}

#app .container {
  max-width: 700px;
  height: 50%;
  margin-bottom: 100px;

  display: flex;
  flex-flow: column;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

header p {
  font-size: 14px;
}

.button__container {
  width: 150px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transform: translateX(20%);

  color: #fff;
}

button {
  flex: 0 0 100px;
  height: 100px;
  border-radius: 50%;

  padding: 0.5em 1em;
  position: relative;

  background-color: rgb(183, 172, 172);
  border: none;
  color: #222;

  text-align: center;
  text-indent: -999px;

  font-size: 1em;
  font-weight: bold;
  box-shadow: 2px 1px 5px rgba(0, 0, 0, 0.3);

  overflow: hidden;
}

button::after {
  content: "버튼";
  /* text-indent: 0px; */

  display: flex;
  justify-content: center;
  align-items: center;

  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);

  color: #fff;
}

button:hover::after {
  text-indent: 0px;
}

button::before {
  content: "";

  display: flex;
  justify-content: center;
  align-items: center;

  width: 90%;
  height: 90%;
  border-radius: 50%;

  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);

  background-color: #b33333;
  background-image: radial-gradient(
    farthest-corner at 30% 30%,
    #ff9494 1%,
    #f03131 5%,
    #b52e2e 30%,
    #4b0f0f 70%
  );
  color: #eee;
}

footer {
  display: flex;
  flex-flow: column;
  gap: 10px;

  font-size: 12px;
  font-weight: 500;
}

footer a {
  padding: 6px 16px;
  border-radius: 20px;

  background-color: #fff;
  border: 1px solid #eee;
  box-shadow: 2px 2px 3px rgba(0, 0, 0, 0.2);

  transition: all 0.2s;
}

#app.active footer a {
  transition: none;
  color: red;
  text-shadow: -2px -2px 0 rgba(0, 0, 0, 0.5);
}

footer a:hover {
  transform: translateY(-2px);
}

#app.active footer a:hover {
  transform: translateY(-30px);
}

/* accent 스타일 */

#app.accent {
  background-color: rgb(251, 0, 255);
  color: rgb(225, 255, 0);
  font-weight: 500;

  cursor: not-allowed !important;
}

#app.accent button {
  animation: blink 0.5s infinite;
}

#app.accent header {
  animation: blink 2s infinite;
}

#app.accent a {
  animation: blink 1.5s infinite;
}

@keyframes blink {
  0% {
    opacity: 0;
  }

  50% {
    opacity: 1;

    transform: scale(1.1);
  }

  100% {
    opacity: 0;
  }
}