html, body {
  padding: 0;
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(1200px 800px at 10% -10%, rgba(124,196,255,0.15), transparent 60%),
    radial-gradient(1000px 700px at 120% 10%, rgba(255,213,112,0.12), transparent 55%),
    #0b1220; /* base bg */
  color: #e6eefc;       /* base text */
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.6;
}

body {
  margin: 0 auto;
  padding: 16px;
}

h1, h2 {
  text-align: center;
  letter-spacing: 0.2px;
  margin: 18px 0 12px;
}

h1 {
  font-size: 42px;
  font-weight: 800;
  background: linear-gradient(90deg, #e6eefc, #7cc4ff);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

h2 {
  font-size: 28px;
  font-weight: 700;
  color: #e6eefc;
}

nav {
  position: sticky;
  top: 12px;
  z-index: 20;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px 14px;
  padding: 10px 14px;
  margin: 18px auto 22px;
  background: linear-gradient(180deg, #121a2b, #0f1627);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 999px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.35);
}

nav a {
  text-decoration: none;
  color: #e6eefc;
  font-weight: 700;
  font-size: 14px;
  padding: 10px 14px;
  border-radius: 999px;
  transition: transform .12s ease, background-color .12s ease, color .12s ease, box-shadow .12s ease;
  outline: none;
}

nav a:hover,
nav a:focus {
  background: rgba(124,196,255,0.15);
  color: #7cc4ff;
  box-shadow: 0 2px 10px rgba(124,196,255,0.25);
  transform: translateY(-1px);
}

body > img:first-of-type,
body > .card,
body > .content,
body > .section {
  display: block;
  background: #0f1627;
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 18px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.35);
  padding: 18px;
  margin: 18px auto;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: 12px;
  box-shadow: 0 12px 30px rgba(0,0,0,0.35);
  margin: 12px auto 18px;
}

p {
  color: #e6eefc;
  margin: 8px auto;
  text-align: left;
  line-height: 1.6;
  max-width: 900px;
}

p b {
  color: #ffd570;
  font-weight: 800;
}

a { color: #7cc4ff; }
a:hover { text-decoration: underline; }

.apod,
.pic {
  background: #0f1627;
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 18px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.35);
  padding: 18px;
  margin: 18px auto;
}

.apod img,
.pic img { margin-top: 6px; }

.apod .meta,
.pic .meta { color: #a9bbd9; font-size: 14px; }

footer { text-align: center; }
footer p { 
  text-align: center;
  padding-left: 0; 
  padding-right: 0; 
  margin: 6px 0 0;
  max-width: none; 
}

footer hr {
  border: none;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.08), transparent);
  margin-bottom: 12px;
}

@media (max-width: 640px) {
  body { padding: 16px; }
  h1 { font-size: 32px; }
  h2 { font-size: 24px; }
  nav { gap: 8px 10px; padding: 8px 10px; }
}