index.css

html {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen",
    "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue",
    sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color: #252527;
  background: #fd746c;  /* fallback for old browsers */
  background: -webkit-linear-gradient(to right, #ff9068, #fd746c);
  background: linear-gradient(to right, #ff9068, #fd746c);
}

.app {
  margin: 40px;
}

@media screen and (min-width:900px) {
  .app {
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
  }
}

.title {
  margin: 20px 0;
}

.posts-search__form {
  margin-bottom: 40px;
}

.posts-search__search-field {
  width: 100%;
  padding: 20px;
  font-size: 25px;
  border: none;
}

.results {
  display: flex;
  flex-wrap: wrap;
}

@media screen and (min-width: 695px) {
  .results {
    margin-right: -20px;
  }
}

.post-card {
  background: rgba(0,0,0,0.1);
  background: rgba(37, 37, 39, 0.1);
  padding: 20px;
  margin-bottom: 20px;
  flex: 1 1 300px;
}

@media screen and (min-width: 695px) {
  .post-card {
    margin-right: 20px;
  }
}

.post-card__image {
  height: auto;
  max-width: 100%;
  margin-bottom: 20px;
}

.post-card__heading {
  margin: 0 0 20px;
}

.post-card__detail {
  display: block;
}

.post-card__label {
  font-weight: 700;
}