:root {
  --bg: #0a0a12;
  --surface: #12121e;
  --border: #2a2a3c;
  --border-focus: #6366f1;
  --text: #e2e2ea;
  --text-dim: #8888a0;
  --accent: #818cf8;
  --accent-hover: #a5b4fc;
  --danger: #f87171;
  --danger-bg: rgba(248, 113, 113, 0.1);
  --success: #34d399;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "Courier New", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", sans-serif;
  --radius: 6px;
}

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

html, body {
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
}

body {
  display: flex;
  justify-content: center;
  padding: 24px 16px 48px;
}

.container {
  width: 100%;
  max-width: 740px;
}

header {
  text-align: center;
  margin-bottom: 28px;
}

h1 {
  font-size: clamp(22px, 5vw, 32px);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--accent);
}

.subtitle {
  margin-top: 4px;
  font-size: 13px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.editor {
  margin-bottom: 12px;
}

label {
  display: block;
  margin-bottom: 6px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-dim);
}

textarea {
  display: block;
  width: 100%;
  padding: 14px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.55;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  resize: vertical;
  outline: none;
  transition: border-color 0.15s;
  tab-size: 2;
}

textarea:focus {
  border-color: var(--border-focus);
}

textarea[readonly] {
  cursor: default;
  color: #c8c8d8;
}

.toolbar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

button {
  appearance: none;
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.03em;
  padding: 9px 20px;
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  background: rgba(99, 102, 241, 0.12);
  color: var(--accent);
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

button:hover {
  background: rgba(99, 102, 241, 0.25);
  color: var(--accent-hover);
  border-color: var(--accent-hover);
}

button:active {
  transform: translateY(1px);
}

button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.btn-secondary {
  border-color: var(--border);
  background: transparent;
  color: var(--text-dim);
}

.btn-secondary:hover {
  border-color: var(--text-dim);
  background: rgba(136, 136, 160, 0.1);
  color: var(--text);
}

.error {
  padding: 10px 14px;
  margin-bottom: 12px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.45;
  color: var(--danger);
  background: var(--danger-bg);
  border: 1px solid rgba(248, 113, 113, 0.3);
  border-radius: var(--radius);
}

.footnote {
  margin-top: 32px;
  text-align: center;
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--text-dim);
  opacity: 0.5;
}

.copy-flash {
  color: var(--success) !important;
  border-color: var(--success) !important;
  background: rgba(52, 211, 153, 0.12) !important;
}

@media (max-width: 480px) {
  .toolbar { gap: 6px; }
  button { flex: 1; min-width: 0; padding: 9px 10px; }
}