:root {
  --bg: #fff;
  --text: #1a1a1a;
  --card-bg: #f5f5f5;
  --border: #e0e0e0;
}

[data-theme="dark"] {
  --bg: #1a1a1a;
  --text: #e0e0e0;
  --card-bg: #2a2a2a;
  --border: #404040;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.2s, color 0.2s;
}

header {
  text-align: center;
  padding: 2rem 1rem;
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 100;
  border-bottom: 1px solid var(--border);
}

.logo {
  max-width: 350px;
  width: 100%;
  height: auto;
}

.theme-toggle {
  position: absolute;
  top: 2rem;
  right: 1rem;
  background: var(--card-bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.5rem 1rem;
  border-radius: 4px;
  cursor: pointer;
  font-size: 1rem;
}

.theme-toggle:hover {
  opacity: 0.8;
}

.feed {
  max-width: 800px;
  margin: 0 auto;
  padding: 1rem;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 1.5rem;
  overflow: hidden;
}

.card img {
  width: 100%;
  height: auto;
  display: block;
}

.card-content {
  padding: 1rem;
}

@media (max-width: 600px) {
  header {
    padding: 1rem;
  }
  
  .theme-toggle {
    top: 1rem;
    right: 0.5rem;
    padding: 0.4rem 0.8rem;
    font-size: 0.9rem;
  }
  
  .logo {
    max-width: 250px;
  }
}