:root {
  color-scheme: light dark;
  --radius: 10px;
  --font: "Segoe UI", system-ui, -apple-system, sans-serif;

  --bg: #f4f6f9;
  --bg-gradient-start: #eef1f6;
  --bg-gradient-mid: #f8f9fb;
  --bg-gradient-end: #e8ecf2;
  --surface: #ffffff;
  --input-bg: #ffffff;
  --border: #c5ced9;
  --text: #1a2332;
  --muted: #5c6b7f;
  --accent: #b91c34;
  --accent-hover: #991b2b;
  --error: #c53030;
  --warning: #b7791f;
  --shadow: rgba(26, 35, 50, 0.08);
  --spinner-track: rgba(255, 255, 255, 0.35);
  --spinner-head: #ffffff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419;
    --bg-gradient-start: #0a0e14;
    --bg-gradient-mid: #1a2332;
    --bg-gradient-end: #0f1419;
    --surface: #1a2332;
    --input-bg: #0f1419;
    --border: #2d3a4d;
    --text: #e8edf4;
    --muted: #8b9cb3;
    --accent: #e63950;
    --accent-hover: #c41e3a;
    --error: #ff6b6b;
    --warning: #f0ad4e;
    --shadow: rgba(0, 0, 0, 0.35);
    --spinner-track: rgba(255, 255, 255, 0.3);
    --spinner-head: #ffffff;
  }
}

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

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  background: linear-gradient(
    160deg,
    var(--bg-gradient-start) 0%,
    var(--bg-gradient-mid) 50%,
    var(--bg-gradient-end) 100%
  );
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.5;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.app {
  max-width: 520px;
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.header {
  text-align: center;
  margin-bottom: 2rem;
}

.header h1 {
  margin: 0 0 0.35rem;
  font-size: clamp(1.35rem, 4vw, 1.65rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.main {
  flex: 1;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: 0 8px 32px var(--shadow);
  transition: background-color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.card h2 {
  margin: 0 0 0.5rem;
  font-size: 1.2rem;
}

.hint {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0 0 1.25rem;
}

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.toolbar h2 {
  margin: 0;
}

.hidden {
  display: none !important;
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

input[type="password"],
input[type="text"] {
  width: 100%;
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--input-bg);
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 1rem;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

input::placeholder {
  color: var(--muted);
  opacity: 0.7;
}

input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

fieldset {
  border: none;
  margin: 0 0 1.25rem;
  padding: 0;
}

legend {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.6rem;
  padding: 0;
}

.radio {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 400;
  margin-bottom: 0.5rem;
  cursor: pointer;
}

.radio input {
  accent-color: var(--accent);
}

.field {
  margin-bottom: 1.25rem;
}

.field input {
  margin-bottom: 0.35rem;
}

.char-counter {
  margin: 0;
  font-size: 0.8rem;
  color: var(--muted);
}

.char-counter.warning {
  color: var(--warning);
}

.char-counter.limit {
  color: var(--error);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.7rem 1.25rem;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.btn:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

.btn-primary {
  width: 100%;
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover:not(:disabled) {
  background: var(--accent-hover);
}

.btn-ghost {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 0.4rem 0.75rem;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.btn-ghost:hover {
  color: var(--text);
  border-color: var(--muted);
}

.error {
  color: var(--error);
  font-size: 0.875rem;
  margin: 0 0 1rem;
}

#generate-form .btn-primary {
  margin-top: 0.5rem;
}

.spinner {
  width: 1.1rem;
  height: 1.1rem;
  border: 2px solid var(--spinner-track);
  border-top-color: var(--spinner-head);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.footer {
  text-align: center;
  margin-top: 2rem;
  color: var(--muted);
  font-size: 0.8rem;
}

.footer p {
  margin: 0;
}

@media (max-width: 480px) {
  .app {
    padding: 1.25rem 1rem 2rem;
  }

  .card {
    padding: 1.25rem;
  }

  .toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .btn-ghost {
    align-self: flex-end;
  }
}