:root {
  --bg: #0f172a;
  --surface: #111827;
  --surface-alt: #1f2937;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, system-ui, sans-serif;
  background: radial-gradient(circle at top, #1e293b 0%, #0f172a 55%);
  color: var(--text);
}

.container {
  max-width: 960px;
  margin: 2rem auto;
  padding: 0 1rem;
  display: grid;
  gap: 1.5rem;
}

.card {
  background: rgba(15, 23, 42, 0.96);
  border: 1px solid rgba(148, 163, 184, 0.12);
  border-radius: 1.25rem;
  padding: 1.5rem;
  box-shadow: 0 20px 80px rgba(15, 23, 42, 0.32);
}

header h1,
header h2 {
  margin: 0 0 0.5rem;
  font-size: clamp(1.6rem, 2vw, 2.4rem);
}

header p {
  margin: 0;
  color: var(--muted);
}

.output-panel {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: 1fr auto;
  margin: 1rem 0;
}

.output-panel input {
  width: 100%;
  padding: 1rem 1rem;
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 0.9rem;
  background: #111827;
  color: var(--text);
  font-size: 0.95rem;
}

.output-panel button {
  border: none;
  border-radius: 0.9rem;
  padding: 1rem 1.25rem;
  background: rgba(56, 189, 248, 0.18);
  color: var(--accent);
  cursor: pointer;
  font-weight: 600;
}

.controls {
  display: grid;
  gap: 1.25rem;
}

.control-group {
  display: grid;
  gap: 0.75rem;
}

.checker-input-group .checker-input-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.toggle-button {
  border: 1px solid rgba(148, 163, 184, 0.2);
  border-radius: 0.85rem;
  padding: 0.65rem 0.9rem;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
  cursor: pointer;
  font-size: 0.9rem;
}

.password-hidden {
  -webkit-text-security: disc;
}

.control-group textarea {
  width: 100%;
  min-height: 8rem;
  padding: 1rem;
  border: 1px solid rgba(148, 163, 184, 0.16);
  border-radius: 0.9rem;
  background: #111827;
  color: var(--text);
  font-size: 0.95rem;
  resize: vertical;
}

.range-group label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text);
  font-weight: 600;
}

.range-group input[type="range"] {
  width: 100%;
}

.checkbox-group {
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
}

.checkbox-group label {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.9rem 1rem;
  border-radius: 0.9rem;
  background: var(--surface-alt);
  cursor: pointer;
  user-select: none;
}

.checkbox-group input[type="checkbox"] {
  width: 1.05rem;
  height: 1.05rem;
}

.strength-panel {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  color: var(--text);
}

.strength-panel strong {
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.strength-panel.weak strong {
  color: var(--danger);
}

.strength-panel.medium strong {
  color: var(--warning);
}

.strength-panel.strong strong {
  color: var(--success);
}

.strength-panel.none strong {
  color: var(--muted);
}

.strength-panel.weak .strength-bar {
  background: rgba(239, 68, 68, 0.18);
}

.strength-panel.medium .strength-bar {
  background: rgba(245, 158, 11, 0.18);
}

.strength-panel.strong .strength-bar {
  background: rgba(34, 197, 94, 0.18);
}

.strength-panel.none .strength-bar {
  background: rgba(148, 163, 184, 0.12);
}

.suggestions-panel {
  width: 100%;
  padding: 1rem;
  margin-top: 1rem;
  border-radius: 1rem;
  background: rgba(148, 163, 184, 0.08);
  color: var(--text);
}

.suggestions-panel ul {
  margin: 0;
  padding-left: 1.25rem;
  display: grid;
  gap: 0.5rem;
}

.suggestions-panel li {
  line-height: 1.5;
}

.suggestions-panel .suggestions-strong {
  margin: 0;
  font-weight: 600;
}

.strength-bar {
  flex: 1 1 100%;
  min-height: 0.75rem;
  border-radius: 999px;
  overflow: hidden;
  position: relative;
  background: rgba(148, 163, 184, 0.12);
}

.strength-fill {
  display: block;
  height: 100%;
  width: 0%;
  border-radius: inherit;
  transition: width 0.25s ease, background 0.25s ease;
  background: transparent;
}

.primary-button {
  border: none;
  border-radius: 0.95rem;
  padding: 1rem 1.25rem;
  background: linear-gradient(135deg, #38bdf8, #60a5fa);
  color: #0f172a;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
}

.advice-card {
  background: rgba(31, 41, 55, 0.98);
}

.advice-list {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.learning-modules {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.module-card {
  border: 1px solid rgba(148, 163, 184, 0.12);
  border-radius: 1rem;
  padding: 1rem;
  background: rgba(15, 23, 42, 0.9);
}

.module-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
}

.module-card p {
  margin: 0 0 1rem;
  color: var(--muted);
  line-height: 1.6;
}

.module-question {
  margin-bottom: 1rem;
  color: var(--text);
}

.module-actions {
  display: grid;
  gap: 0.75rem;
}

.module-button {
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: 0.95rem;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  padding: 0.9rem 1rem;
  cursor: pointer;
  text-align: left;
}

.module-button:hover {
  background: rgba(56, 189, 248, 0.12);
}

.module-button.correct {
  border-color: rgba(34, 197, 94, 0.45);
  background: rgba(34, 197, 94, 0.16);
}

.module-button.incorrect {
  border-color: rgba(239, 68, 68, 0.45);
  background: rgba(239, 68, 68, 0.12);
}

.module-button[disabled] {
  opacity: 0.7;
  cursor: default;
}

.module-feedback {
  margin-top: 0.75rem;
  padding: 0.85rem 1rem;
  border-radius: 0.95rem;
  color: var(--text);
  background: rgba(31, 41, 55, 0.95);
}

.module-feedback.correct {
  border: 1px solid rgba(34, 197, 94, 0.35);
  background: rgba(34, 197, 94, 0.12);
}

.module-feedback.incorrect {
  border: 1px solid rgba(239, 68, 68, 0.35);
  background: rgba(239, 68, 68, 0.12);
}

.advice-item {
  border: 1px solid rgba(148, 163, 184, 0.12);
  border-radius: 1rem;
  padding: 1rem;
  background: rgba(15, 23, 42, 0.9);
}

.advice-item h3 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
}

.advice-item p {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

.checker-card textarea {
  min-height: 8rem;
}

@media (max-width: 640px) {
  .output-panel {
    grid-template-columns: 1fr;
  }
}