* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", sans-serif;
  background: #0d1117;
  color: #e6edf3;
}

header {
  text-align: center;
  padding: 1.5rem;
  background: #161b22;
}

nav {
  margin-top: 10px;
}

nav button {
  margin: 5px;
  padding: 8px 15px;
}

main {
  padding: 1rem;
  max-width: 1000px;
  margin: auto;
}

.card {
  background: #161b22;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  border-radius: 12px;
}

.hero {
  text-align: center;
  padding: 3rem 1rem;
  background: linear-gradient(to right, #0f2027, #203a43, #2c5364);
  border-radius: 12px;
  margin-bottom: 1.5rem;
}

input, button {
  padding: 10px;
  margin-top: 10px;
  width: 100%;
}

button {
  background: #238636;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

button:hover {
  background: #2ea043;
}

img {
  width: 100%;
  border-radius: 10px;
  margin-top: 10px;
  cursor: pointer;
}

.hidden {
  display: none;
}

.error {
  color: #ff6b6b;
}

/* Gallery Grid */
#apodContainer {
  display: grid;
  grid-template-columns: 1fr;
  gap: 15px;
}

.gallery-item {
  background: #0d1117;
  padding: 10px;
  border-radius: 10px;
}

/* Spinner */
.spinner {
  border: 4px solid #333;
  border-top: 4px solid #58a6ff;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  margin: 20px auto;
  animation: spin 1s linear infinite;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}
@media (min-width: 768px) {
  #apodContainer {
    grid-template-columns: repeat(2, 1fr);
  }
  form {
    display: flex;
    gap: 10px;
  }
  input {
    flex: 1;
  }
  button {
    width: auto;
  }
}