body {
  font-family: system-ui, sans-serif;
  max-width: 800px;
  margin: 0 auto;
  padding: 1rem;
  background: #fafafa;
}
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid #ddd;
  padding-bottom: 0.5rem;
}
nav a, nav button {
  margin-left: 1rem;
}
.post {
  background: white;
  border-radius: 8px;
  padding: 1rem;
  margin: 1rem 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}
.post img {
  max-width: 100%;
  height: auto;
  margin-top: 0.5rem;
}
.auth-container {
  max-width: 400px;
  margin: 4rem auto;
  background: white;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}