:root {
  --bg: #050716;
  --bg-gradient: radial-gradient(circle at top, #319795 0, #050716 45%, #000 100%);
  --card-bg: rgba(12, 13, 35, 0.97);
  --accent: #38b2ac;
  --accent-soft: rgba(56, 178, 172, 0.18);
  --accent2: #81e6d9;
  --border: #262b45;
  --border-soft: #1a1e33;
  --text: #f6f7ff;
  --muted: #aab1d8;
  --muted-soft: #8a92c4;
  --correct: #38a169;
  --wrong: #e53e3e;
  --shadow: 0 18px 40px rgba(0, 0, 0, 0.65);
  --radius-lg: 18px;
  --radius-md: 14px;
  --radius-pill: 999px;
}

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

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg-gradient);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.app {
  max-width: 1200px;
  margin: 24px auto;
  padding: 0 16px 32px;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  border: 1px solid rgba(129, 230, 217, 0.07);
  box-shadow: var(--shadow);
}

/* Header */

.app-header {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: center;
  padding: 16px 22px;
  margin-bottom: 18px;
}

.header-main {
  display: flex;
  align-items: center;
  gap: 16px;
}

.logo-wrap {
  width: 70px;
  height: 70px;
  border-radius: 20px;
  background: radial-gradient(circle at 20% 0%, rgba(255, 255, 255, 0.2), transparent 55%);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.logo-circle {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  border: 2px solid var(--accent2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  letter-spacing: 0.08em;
  font-size: 0.82rem;
}

.title-block h1 {
  margin: 0 0 4px;
  font-size: 1.7rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.title-block h1 span {
  color: var(--accent2);
}

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

.header-controls {
  display: flex;
  gap: 10px;
  align-items: center;
}

.status-pill {
  border-radius: var(--radius-pill);
  padding: 6px 16px;
  font-size: 0.85rem;
  background: rgba(7, 10, 30, 0.95);
  border: 1px solid var(--border-soft);
  color: var(--muted);
}

.status-pill span {
  color: var(--accent2);
  font-weight: 600;
}

.status-pill.secondary {
  background: rgba(255, 255, 255, 0.02);
}

/* Main layout */

.main-layout {
  display: grid;
  grid-template-columns: minmax(0, 2.1fr) minmax(260px, 1fr);
  gap: 18px;
  margin-bottom: 16px;
  padding: 18px 20px;
}

.puzzle-panel {
  padding-right: 18px;
  border-right: 1px solid var(--border-soft);
}

.help-panel {
  padding-left: 18px;
}

/* Lock UI */

.room-intro h2 {
  margin: 0 0 4px;
  font-size: 1.2rem;
}

.room-intro p {
  margin: 0 0 10px;
  font-size: 0.9rem;
  color: var(--muted-soft);
}

.lock-progress {
  display: flex;
  gap: 10px;
  margin: 10px 0 14px;
}

.lock {
  width: 36px;
  height: 36px;
  border-radius: 12px;
  border: 1px solid var(--border-soft);
  background: rgba(7, 9, 26, 0.98);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  font-weight: 600;
  font-size: 0.9rem;
  position: relative;
}

.lock::before {
  content: "";
  position: absolute;
  top: -10px;
  width: 16px;
  height: 10px;
  border-radius: 999px 999px 0 0;
  border: 2px solid var(--border-soft);
  border-bottom: none;
}

.lock span {
  position: relative;
  z-index: 2;
}

.lock.current {
  border-color: var(--accent2);
  box-shadow: 0 0 0 1px rgba(129, 230, 217, 0.5);
  color: var(--accent2);
}

.lock.unlocked {
  background: radial-gradient(circle at top, var(--accent), #276749);
  border-color: var(--correct);
  color: #f0fff4;
}

/* Puzzle box */

.puzzle-box {
  background: radial-gradient(circle at top left, var(--accent-soft), transparent 58%);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-soft);
  padding: 14px 16px 16px;
}

.puzzle-question {
  margin: 0 0 10px;
  font-size: 0.98rem;
  line-height: 1.5;
}

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  margin: 8px 0 8px;
}

.option-btn {
  width: 100%;
  text-align: left;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-soft);
  background: rgba(7, 9, 26, 0.98);
  padding: 8px 10px;
  font-size: 0.9rem;
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.12s ease, background 0.12s ease, transform 0.08s ease,
    box-shadow 0.08s ease;
}

.option-btn:hover {
  border-color: var(--accent2);
  background: rgba(56, 178, 172, 0.12);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.6);
  transform: translateY(-1px);
}

.option-btn.selected {
  border-color: var(--accent);
  background: rgba(56, 178, 172, 0.18);
}

.input-area {
  margin: 8px 0;
}

.input-area input {
  width: 100%;
  padding: 8px 10px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--border-soft);
  background: rgba(7, 9, 26, 0.98);
  color: var(--text);
  font-size: 0.9rem;
}

.input-area input:focus {
  outline: none;
  border-color: var(--accent2);
  box-shadow: 0 0 0 1px rgba(129, 230, 217, 0.4);
}

.code-clue {
  margin: 6px 0 8px;
  padding: 8px 10px;
  border-radius: 10px;
  background: rgba(7, 9, 26, 0.96);
  border: 1px dashed var(--border-soft);
  font-family: "Fira Code", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
    "Liberation Mono", "Courier New", monospace;
  font-size: 0.82rem;
  color: var(--muted-soft);
}

/* Buttons / controls */

.controls-row {
  display: flex;
  gap: 10px;
  margin-top: 10px;
  flex-wrap: wrap;
}

.btn {
  border-radius: var(--radius-pill);
  border: none;
  padding: 8px 18px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease, background 0.12s ease, opacity 0.12s ease;
  font-weight: 600;
}

.btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  color: #050716;
  box-shadow: 0 12px 28px rgba(10, 148, 140, 0.7);
}

.btn.primary:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 16px 32px rgba(10, 148, 140, 0.95);
}

.btn.secondary {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  border: 1px solid var(--border-soft);
}

.btn.secondary:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.08);
}

.btn:disabled {
  opacity: 0.4;
  cursor: default;
}

/* Feedback / explanation */

.feedback {
  margin-top: 8px;
  font-size: 0.9rem;
  padding: 7px 10px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-soft);
  color: var(--muted);
}

.feedback.good {
  border-color: var(--correct);
  background: rgba(56, 161, 105, 0.12);
  color: #c6f6d5;
}

.feedback.bad {
  border-color: var(--wrong);
  background: rgba(229, 62, 62, 0.12);
  color: #fed7d7;
}

.link-btn {
  background: none;
  border: none;
  color: var(--accent2);
  padding: 0;
  font-size: 0.85rem;
  cursor: pointer;
  text-decoration: underline;
  margin-top: 6px;
}

.explanation {
  margin-top: 6px;
  font-size: 0.86rem;
  line-height: 1.6;
  color: var(--muted-soft);
  padding: 8px 10px;
  border-radius: 10px;
  background: rgba(5, 7, 22, 0.97);
  border: 1px solid var(--border-soft);
}

.hidden {
  display: none;
}

/* Help panel */

.help-panel h2 {
  margin-top: 0;
  margin-bottom: 8px;
  font-size: 1rem;
}

.ref-list {
  margin: 0 0 10px;
  padding-left: 18px;
  font-size: 0.86rem;
  color: var(--muted-soft);
}

.ref-list li + li {
  margin-top: 5px;
}

.hint {
  margin: 0;
  font-size: 0.85rem;
  color: var(--muted);
}

/* Footer */

.footer-card {
  margin-top: 12px;
  padding: 10px 14px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--muted);
}

/* Responsive */

@media (max-width: 860px) {
  .app-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .main-layout {
    grid-template-columns: 1fr;
  }

  .puzzle-panel {
    padding-right: 0;
    border-right: none;
    border-bottom: 1px solid var(--border-soft);
    margin-bottom: 10px;
    padding-bottom: 12px;
  }

  .help-panel {
    padding-left: 0;
  }

  .header-controls {
    width: 100%;
    justify-content: flex-start;
    gap: 8px;
    margin-top: 8px;
  }
}