*,
*::before,
*::after {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  line-height: 1.5;
  margin: 0;
  background-color: #f5f5f5;
  display: grid;
  grid-template-rows: auto 1fr auto;
  grid-template-columns: 1fr;
  min-height: 100vh;
  justify-items: center;
  align-items: center;
  color: #2c3e50;
}
h1 {
  text-align: center;
  color: #2c3e50;
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

header {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem;
  @media (min-width: 480px) {
    padding: 1rem;
  }
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  grid-row-start: 2;
  padding: 0.5rem;
  @media (min-width: 480px) {
    padding: 1rem;
  }
}

footer {
  grid-row-start: 3;
  padding: 0.5rem;
  font-weight: 500;

  @media (min-width: 480px) {
    padding: 2rem;
  }
}

.pwa-button {
  background-color: #3498db;
  color: white;
  border: none;
  padding: 0.75rem;
  border-radius: 6px;
  font-weight: semibold;
  font-size: 1rem;
  cursor: pointer;
  transition: background-color 0.2s;
}

.pwa-button:hover {
  background-color: #2980b9;
}

.pwa-button--sm {
  font-size: 0.85rem;
  padding: 0.5rem;
}

.buttons {
  display: flex;
  gap: 1rem;
}

.captcha {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
}
.description {
  text-align: center;
  padding: 1rem;
}

.captcha__solver {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);

  border: 2px solid #2980b9;
  width: 100%;
  aspect-ratio: 1/1;

  @media (min-width: 420px) {
    width: 400px;
    height: 400px;
    padding: 1rem;
  }
}

.grid-cell {
  outline: 0;
}

.grid-cell[data-valid="true"] {
  background: greenyellow;
  border: 2px solid greenyellow;
}