* { box-sizing: border-box; }
:root {
  --bg: #0f172a;
  --card: #111827;
  --muted: #94a3b8;
  --text: #e5e7eb;
  --primary: #22d3ee;
  --primary-600: #0891b2;
}
html, body {
  height: 100%;
}
body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: linear-gradient(180deg, #0b1220 0%, #0b1220 60%, #0d1526 100%);
}
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 20px;
}
.site-header {
  background: rgba(17,24,39,0.6);
  border-bottom: 1px solid rgba(255,255,255,0.06);
  position: sticky;
  top: 0;
  backdrop-filter: blur(8px);
  z-index: 20;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  font-weight: 700;
  letter-spacing: 0.5px;
}
.nav a {
  color: var(--muted);
  margin-left: 16px;
  text-decoration: none;
}
.nav a:hover { color: var(--text); }

.hero {
  padding: 64px 0 40px;
  text-align: center;
}
.hero h1 {
  font-size: 40px;
  margin: 0 0 12px 0;
}
.subtitle {
  color: var(--muted);
  margin: 0 0 24px 0;
}
.convert-form {
  display: flex;
  gap: 12px;
  margin: 0 auto;
  max-width: 820px;
}
.convert-form input {
  flex: 1;
  padding: 14px 16px;
  border-radius: 10px;
  border: 1px solid rgba(255,255,255,0.1);
  background: var(--card);
  color: var(--text);
}
.convert-form button {
  padding: 14px 20px;
  border-radius: 10px;
  border: 0;
  background: linear-gradient(90deg, var(--primary), #60a5fa);
  color: #0b1220;
  font-weight: 700;
  cursor: pointer;
}
.convert-form button:hover {
  filter: brightness(1.05);
}
/* Generic card, usable across pages */
.card {
  background: rgba(17,24,39,0.7);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.25);
}
/* Feedback form layout */
.feedback-form {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 20px 0 0 0;
}
.feedback-form .form-control {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.feedback-form .form-control label {
  font-weight: 600;
}
.feedback-form input,
.feedback-form textarea {
  padding: 14px 16px;
  border-radius: 10px;
  border: 1px solid rgba(255,255,255,0.1);
  background: var(--card);
  color: var(--text);
}
.feedback-form .form-control.full {
  grid-column: 1 / -1;
}
.feedback-form .error {
  color: #fca5a5;
  font-size: 14px;
}
.form-actions {
  grid-column: 1 / -1;
  display: flex;
  justify-content: flex-end;
  margin-top: 8px;
}
.btn-primary {
  padding: 14px 20px;
  border-radius: 10px;
  border: 0;
  background: linear-gradient(90deg, var(--primary), #60a5fa);
  color: #0b1220;
  font-weight: 700;
  cursor: pointer;
}
.btn-primary:hover { filter: brightness(1.05); }
.status {
  margin: 16px auto 0;
  max-width: 820px;
  color: var(--muted);
}
.result .card {
  margin: 24px auto 0;
  max-width: 820px;
  background: rgba(17,24,39,0.7);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 12px;
  padding: 20px;
}
.muted { color: var(--muted); }
.btn {
  display: inline-block;
  margin-top: 8px;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--primary);
  color: #0b1220;
  font-weight: 700;
  text-decoration: none;
}
.raw-json {
  margin-top: 16px;
  background: #0a0f1a;
  color: #e2e8f0;
  padding: 12px;
  border-radius: 8px;
  overflow-x: auto;
}
.how, .faq {
  padding: 48px 0;
}
.site-footer {
  padding: 24px 0 40px;
  color: var(--muted);
  text-align: center;
}
.hidden { display: none; }

/* Feedback page presentation */
.page-header {
  padding: 56px 0 20px;
  text-align: center;
}
.page-header h1 {
  font-size: 36px;
  margin: 0 0 8px 0;
}
.page-header .subtitle {
  color: var(--muted);
  margin: 0;
}
.narrow {
  max-width: 760px;
  margin: 0 auto;
}
.feedback-card {
  margin: 20px auto 0;
}
.feedback-form .form-actions {
  margin-top: 4px;
}
.feedback-form .hint {
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 640px) {
  .convert-form { flex-direction: column; }
  .feedback-form { grid-template-columns: 1fr; }
}