body {
  margin: 0;
  padding: 24px;
  color: #202124;
  font: 16px system-ui, sans-serif;
}

main {
  max-width: 1100px;
  margin: 0 auto;
}

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

#posts_box {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
  gap: 16px;
}

.post {
  min-width: 0;
  padding: 12px;
  border: 1px solid #c7c9cc;
  border-radius: 4px;
}

form {
  display: grid;
  max-width: 560px;
  gap: 8px;
}

input,
button {
  font: inherit;
}

input {
  width: 100%;
  box-sizing: border-box;
  padding: 8px;
}

button {
  width: fit-content;
  padding: 8px 12px;
}

.preview-frame {
  display: block;
  width: 100%;
  min-height: 180px;
  border: 1px solid #c7c9cc;
  background: #fff;
}

@media (max-width: 480px) {
  body {
    padding: 16px;
  }

  .page-header {
    align-items: flex-start;
    flex-direction: column;
  }
}