*, *::before, *::after {
  box-sizing: border-box;
}

html {
  font-size: 100%;
}

body {
  margin: 0;
  font-family: 'Karla', sans-serif;
  background-color: aliceblue;
}

.all-card-info {
  display: flex;
  flex-direction: column;
  width: 80%;
  max-width: 515px;
  margin: 3rem auto;
}

.first-card {
  background-color: #fff;
  padding: 1.2em;
  border-radius: 5px 5px 0 0;
}

.join {
  color: hsl(179, 62%, 43%);
  font-weight: 700;
}

.join-text {
  color: hsl(71, 73%, 54%);
  font-weight: 700;
}

.join-text-info {
  color: hsl(218, 22%, 67%);
  font-weight: 400;
}

.second-card {
  background-color: hsl(179, 62%, 43%);
  padding: 1.2em;
  color: hsl(204, 43%, 93%);
}

p > bold {
  font-size: 2rem;
  font-weight: 700;
}

p > span {
  position: relative;
  top: -0.5em;
  left: 0.5em;
}

.btn {
  width: 100%;
  font-family: 'Karla', sans-serif;
  font-size: 1rem;
  font-weight: 700;
  padding: 0.7em 0;
  margin: 1rem 0;
  border: none;
  color: #fff;
  background-color: hsl(71, 73%, 54%);
  border-radius: 5px;
  cursor: pointer;
  box-shadow: 0 5px 20px hsl(0, 0%, 0%, 0.25);
}

.btn:hover {
  background-color: #fff;
  color: hsl(71, 73%, 54%);
}

.btn:focus {
  background-color: hsl(71, 73%, 54%, 0.8);
  color: #fff;
}

.third-card {
  background: hsla(179, 62%, 43%, 0.7);
  padding: 1.2em;
  color: hsl(204, 43%, 93%);
  border-radius: 0 0 5px 5px;
}

.about-list {
  list-style-type: none;
}

dt > strong {
  font-weight: 700;
}

dd:first-of-type {
  margin-top: 1rem;
}

dd {
  margin-left: 0;
  line-height: 1.4rem;
  font-weight: 400;
}

.attribution { 
  font-size: 11px; 
  text-align: center; 
}

.attribution a { 
  color: hsl(228, 45%, 44%); 
}

@media screen and (min-width: 900px) {
  .all-card-info {
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    max-width: 710px;
    justify-content: center;
    align-items: center;
  }

  .first-card {
    flex-basis: 80%;
  }

  .second-card {
    flex-basis: 40%;
    border-radius: 0 0 0 5px;
  }

  .third-card {
    flex-basis: 40%;
    border-radius: 0 0 5px 0;
  }

}