* { box-sizing: border-box; }

html[data-theme="dark"] {
  --bg: #0f1115; --card: #1a1d24; --border: #2a2e37; --text: #e6e6e6;
  --accent: #7dd3fc; --btn: #2563eb; --danger: #dc2626; --muted: #999;
}
html[data-theme="light"] {
  --bg: #f4f5f7; --card: #ffffff; --border: #dcdfe4; --text: #1a1d24;
  --accent: #2563eb; --btn: #2563eb; --danger: #dc2626; --muted: #666;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;
}
.topnav {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 14px 24px;
  display: flex;
  gap: 16px;
  align-items: center;
  flex-wrap: wrap;
}
.topnav a { color: var(--accent); text-decoration: none; font-weight: 600; }
.brand { font-size: 1.2rem; }
.search-form { flex: 1; min-width: 150px; }
.search-form input { width: 100%; }
#theme-toggle {
  margin-left: auto; background: none; border: 1px solid var(--border);
  color: var(--text); border-radius: 6px; padding: 4px 10px; cursor: pointer;
}
main { max-width: 800px; margin: 30px auto; padding: 0 16px; }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  margin-bottom: 20px;
}
.list { list-style: none; padding: 0; }
.list li {
  display: flex; justify-content: space-between; align-items: center;
  padding: 8px 0; border-bottom: 1px solid var(--border); flex-wrap: wrap; gap: 6px;
}
.list a { color: var(--text); }
.inline-form { display: flex; gap: 8px; margin-top: 10px; flex-wrap: wrap; }
input, select, textarea {
  background: var(--bg); border: 1px solid var(--border); color: var(--text);
  border-radius: 6px; padding: 8px;
}
.title-input { width: 100%; font-size: 1.1rem; margin-bottom: 10px; }
button {
  background: var(--btn); color: white; border: none;
  border-radius: 6px; padding: 8px 14px; cursor: pointer;
}
button.danger, .btn.danger { background: var(--danger); }
.btn { display: inline-block; text-decoration: none; }
.flashcard {
  background: var(--card); border: 1px solid var(--border); border-radius: 10px;
  padding: 16px; margin-bottom: 14px;
}
.login-box {
  max-width: 320px; margin: 100px auto; text-align: center;
  background: var(--card); padding: 24px; border-radius: 10px; border: 1px solid var(--border);
}
.login-box form { display: flex; flex-direction: column; gap: 10px; }
.error { color: #f87171; }
.hint { color: var(--muted); font-size: 0.85rem; margin-top: 8px; }
.ai-output { margin-top: 14px; }
.ai-output pre { white-space: pre-wrap; background: var(--bg); padding: 12px; border-radius: 8px; border: 1px solid var(--border); }
.flash { color: #f87171; margin-bottom: 10px; }

@media (max-width: 600px) {
  .topnav { padding: 10px 14px; }
  main { padding: 0 10px; }
  .list li { flex-direction: column; align-items: flex-start; }
}