:root {
  /* Cosmic / deep space */
  --bg-1: #0a0524;
  --bg-2: #1a0a3a;
  --bg-3: #2a1268;
  --text: #ffffff;
  --text-dim: #b0a8d8;
  --accent: #00f0ff;        /* electric cyan */
  --accent-2: #ff45e6;      /* hot magenta */
  --accent-3: #ffd700;      /* gold */
  --correct: #4ade80;
  --wrong: #ff5577;
  --card-bg: rgba(255, 255, 255, 0.05);
  --card-border: rgba(0, 240, 255, 0.18);
  --card-glow: 0 0 24px rgba(0, 240, 255, 0.12);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: radial-gradient(ellipse at top, var(--bg-3) 0%, var(--bg-2) 40%, var(--bg-1) 100%);
  background-attachment: fixed;
  color: var(--text);
  min-height: 100vh;
  padding: 16px;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  overflow-x: hidden;
  position: relative;
}

/* Twinkling starfield */
.stars {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  pointer-events: none; z-index: 0;
  background-image:
    radial-gradient(1px 1px at 12% 18%, #fff, transparent),
    radial-gradient(1px 1px at 34% 72%, #fff, transparent),
    radial-gradient(1.5px 1.5px at 58% 31%, #fff, transparent),
    radial-gradient(1px 1px at 80% 55%, #aef, transparent),
    radial-gradient(1.5px 1.5px at 22% 47%, #fda, transparent),
    radial-gradient(1px 1px at 67% 89%, #fff, transparent),
    radial-gradient(1px 1px at 91% 12%, #fff, transparent),
    radial-gradient(2px 2px at 45% 8%, #fef, transparent),
    radial-gradient(1px 1px at 8% 88%, #fff, transparent),
    radial-gradient(1px 1px at 76% 67%, #cdf, transparent);
  background-size: 700px 700px;
  background-repeat: repeat;
  animation: twinkle 5s infinite alternate;
  opacity: 0.7;
}
@keyframes twinkle { 0%, 100% { opacity: 0.5; } 50% { opacity: 0.9; } }

#app { max-width: 620px; margin: 0 auto; position: relative; z-index: 1; }
.screen { display: flex; flex-direction: column; gap: 16px; }
.hidden { display: none !important; }

/* Home header */
.home-header { text-align: center; padding: 8px 0 4px; }
h1 {
  font-size: 2.4rem; font-weight: 800; letter-spacing: -0.01em;
  background: linear-gradient(120deg, var(--accent) 0%, var(--accent-2) 60%, var(--accent-3) 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  filter: drop-shadow(0 0 18px rgba(0, 240, 255, 0.3));
}
.subtitle { color: var(--text-dim); font-size: 0.95rem; margin-top: 6px; }

.section-title {
  text-align: center; color: var(--text-dim); font-size: 0.9rem;
  text-transform: uppercase; letter-spacing: 0.1em; font-weight: 700;
  margin-top: 4px;
}

/* Name pill */
.name-pill {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 16px;
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: 14px; box-shadow: var(--card-glow);
  max-width: 360px; margin: 0 auto;
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.name-pill-icon { font-size: 1.1rem; }
.name-pill-label { color: var(--text-dim); font-size: 0.92rem; font-weight: 600; }
.name-pill input {
  background: transparent; border: none; color: var(--text);
  font-family: inherit; font-size: 1rem; font-weight: 700;
  text-align: left; flex: 1; outline: none; min-width: 0;
  padding: 2px 0;
  border-bottom: 1px dashed transparent;
  transition: border-color 0.15s;
}
.name-pill input:focus { border-bottom-color: var(--accent); }
.name-pill input::placeholder { color: var(--text-dim); font-style: italic; font-weight: 500; }

/* Mission log */
.mission-log-section {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: 16px; padding: 14px 16px;
  box-shadow: var(--card-glow);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.mission-log-section h3 {
  font-size: 0.92rem; color: var(--accent-3); text-align: center;
  letter-spacing: 0.06em; text-transform: uppercase;
  margin-bottom: 10px; font-weight: 800;
}

/* Stats */
.stats-bar { display: flex; gap: 10px; }
.stat {
  flex: 1; background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: 16px; padding: 14px; text-align: center;
  box-shadow: var(--card-glow);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.stat-label {
  display: block; font-size: 0.75rem; color: var(--text-dim);
  text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 4px; font-weight: 600;
}
.stat-value { font-size: 1.5rem; font-weight: 800; color: var(--accent); font-variant-numeric: tabular-nums; }

/* Progress bar */
.progress-bar { height: 12px; background: rgba(255,255,255,0.06); border-radius: 6px; overflow: hidden; border: 1px solid var(--card-border); }
.progress-fill {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2), var(--accent-3));
  transition: width 0.5s ease;
  box-shadow: 0 0 10px var(--accent);
}

/* Planet grid */
.planets-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px;
}
.planet-btn {
  position: relative;
  background: var(--card-bg); border: 1px solid var(--card-border);
  color: var(--text); border-radius: 16px;
  aspect-ratio: 1; cursor: pointer;
  font-family: inherit; font-weight: 800; font-size: 1.6rem;
  transition: all 0.15s;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  box-shadow: var(--card-glow);
  backdrop-filter: blur(6px); -webkit-backdrop-filter: blur(6px);
  overflow: hidden;
}
.planet-btn::before {
  content: ''; position: absolute; inset: 0;
  background: radial-gradient(circle at 30% 30%, var(--planet-color, var(--accent)) 0%, transparent 65%);
  opacity: 0.18;
  pointer-events: none;
}
.planet-btn:hover {
  transform: translateY(-3px) scale(1.04);
  border-color: var(--planet-color, var(--accent));
  box-shadow: 0 6px 24px rgba(0, 240, 255, 0.22);
}
.planet-btn:active { transform: translateY(-1px) scale(1); }
.planet-emoji { font-size: 1.3rem; margin-bottom: 2px; opacity: 0.9; }
.planet-label { font-size: 1.4rem; color: var(--text); position: relative; z-index: 1; }
.planet-btn.mastered {
  border-color: var(--accent-3);
  box-shadow: 0 0 20px rgba(255, 215, 0, 0.3);
}
.planet-btn.mastered::after {
  content: '⭐'; position: absolute; top: 4px; right: 6px; font-size: 1rem;
}

/* Speed Round button */
.speed-btn {
  background: linear-gradient(135deg, var(--accent-2), var(--accent));
  border: none; color: #1a0a3a; padding: 16px 22px; border-radius: 16px;
  font-weight: 800; cursor: pointer; font-size: 1.1rem; font-family: inherit;
  letter-spacing: 0.02em; text-transform: uppercase;
  box-shadow: 0 4px 24px rgba(255, 69, 230, 0.4);
  transition: transform 0.1s, box-shadow 0.15s;
}
.speed-btn:hover { transform: scale(1.03); box-shadow: 0 8px 32px rgba(255, 69, 230, 0.55); }
.speed-btn:active { transform: scale(0.97); }

/* Settings */
.settings-row {
  display: flex; justify-content: space-between; align-items: center;
  color: var(--text-dim); font-size: 0.9rem; padding: 4px;
}
.settings-row label { display: flex; align-items: center; gap: 6px; cursor: pointer; }
.settings-row input[type="checkbox"] { accent-color: var(--accent); width: 16px; height: 16px; }
.link-btn {
  background: none; border: none; color: var(--text-dim);
  cursor: pointer; text-decoration: underline; font-size: inherit; font-family: inherit;
}
.link-btn:hover { color: var(--accent); }

/* Game screen */
.game-header { display: flex; align-items: center; gap: 10px; }
.back-btn {
  background: var(--card-bg); border: 1px solid var(--card-border);
  color: var(--text); padding: 8px 14px; border-radius: 12px;
  cursor: pointer; font-family: inherit; font-size: 0.92rem; font-weight: 600;
}
.back-btn:hover { background: rgba(255,255,255,0.10); }
.mode-title { flex: 1; text-align: center; font-weight: 800; font-size: 1.1rem; color: var(--accent); }
.game-stat {
  background: var(--card-bg); border: 1px solid var(--card-border);
  padding: 7px 12px; border-radius: 12px; font-size: 0.85rem;
  font-weight: 700; color: var(--text);
  font-variant-numeric: tabular-nums; white-space: nowrap;
}

.game-content {
  padding: 20px 18px;
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: 20px;
  box-shadow: var(--card-glow);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  display: flex; flex-direction: column; gap: 16px;
  min-height: 320px;
}

/* Problem display */
.problem {
  text-align: center;
  font-size: 3rem; font-weight: 800;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.05em;
  padding: 16px 0;
  color: var(--text);
  text-shadow: 0 0 24px rgba(0, 240, 255, 0.4);
}
.problem .x { color: var(--accent-2); margin: 0 8px; }
.problem .equals { color: var(--text-dim); margin: 0 8px; }
.problem .answer-slot {
  color: var(--accent); display: inline-block; min-width: 80px;
  border-bottom: 3px solid var(--accent);
  padding: 0 12px;
}
.problem.correct { animation: pop-correct 0.5s; }
.problem.wrong { animation: shake 0.4s; }
.problem.correct .answer-slot { color: var(--correct); border-bottom-color: var(--correct); }
.problem.wrong .answer-slot { color: var(--wrong); border-bottom-color: var(--wrong); }
@keyframes pop-correct { 0% { transform: scale(1); } 50% { transform: scale(1.12); } 100% { transform: scale(1); } }
@keyframes shake { 0%, 100% { transform: translateX(0); } 25% { transform: translateX(-6px); } 75% { transform: translateX(6px); } }

/* Choices grid */
.choices {
  display: grid; grid-template-columns: 1fr 1fr; gap: 10px;
  margin-top: 6px;
}
.choice {
  background: var(--card-bg); border: 2px solid var(--card-border);
  color: var(--text); padding: 18px; border-radius: 14px;
  font-family: inherit; font-size: 1.6rem; font-weight: 800;
  cursor: pointer; font-variant-numeric: tabular-nums;
  transition: all 0.12s;
}
.choice:hover { background: rgba(0, 240, 255, 0.08); border-color: var(--accent); transform: translateY(-2px); }
.choice:active { transform: scale(0.96); }
.choice.correct {
  background: rgba(74, 222, 128, 0.2); border-color: var(--correct); color: var(--correct);
}
.choice.wrong {
  background: rgba(255, 85, 119, 0.2); border-color: var(--wrong); color: var(--wrong);
}
.choice:disabled { cursor: default; }

/* Study mode — multiplication facts grid */
.study-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin: 4px 0 6px;
}
.fact-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 12px 6px;
  text-align: center;
  display: flex; align-items: center; justify-content: center; gap: 5px;
  font-size: 1.05rem; font-weight: 700;
  font-variant-numeric: tabular-nums;
  transition: transform 0.15s, border-color 0.15s;
}
.fact-card:hover { transform: translateY(-2px); border-color: var(--accent); }
.fact-eq { color: var(--text-dim); }
.fact-eq-eq { color: var(--text-dim); opacity: 0.7; }
.fact-ans { color: var(--accent); font-weight: 800; font-size: 1.2rem; }

@media (max-width: 480px) {
  .study-grid { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .fact-card { font-size: 1rem; padding: 10px 4px; }
  .fact-ans { font-size: 1.1rem; }
}

/* Ladder progress */
.ladder {
  display: grid; grid-template-columns: repeat(12, 1fr); gap: 4px;
  padding: 8px 0;
}
.ladder-rung {
  height: 12px; border-radius: 6px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.1);
}
.ladder-rung.done { background: var(--correct); box-shadow: 0 0 8px var(--correct); }
.ladder-rung.current { background: var(--accent); animation: pulse-glow 1s infinite alternate; }
.ladder-rung.wrong { background: var(--wrong); }
@keyframes pulse-glow {
  from { box-shadow: 0 0 4px var(--accent); }
  to { box-shadow: 0 0 16px var(--accent); }
}

.feedback {
  text-align: center; min-height: 1.4em; font-weight: 700; font-size: 1rem;
}
.feedback.good { color: var(--correct); }
.feedback.bad { color: var(--wrong); }

.position-label { text-align: center; color: var(--text-dim); font-size: 0.95rem; font-weight: 600; }
.instruction { text-align: center; color: var(--text); font-size: 1rem; }

/* Action buttons */
.action-btn {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border: none; color: #0a0524; padding: 14px 26px; border-radius: 14px;
  font-weight: 800; cursor: pointer; font-size: 1rem; font-family: inherit;
  text-transform: uppercase; letter-spacing: 0.04em;
  transition: transform 0.1s, box-shadow 0.15s;
  box-shadow: 0 4px 18px rgba(0, 240, 255, 0.3);
}
.action-btn:hover { transform: scale(1.04); box-shadow: 0 6px 24px rgba(0, 240, 255, 0.5); }
.action-btn:active { transform: scale(0.97); }
.action-btn.secondary {
  background: var(--card-bg); color: var(--text); border: 1px solid var(--card-border); box-shadow: var(--card-glow);
}
.btn-row { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }

/* Name input */
.name-row {
  display: flex; align-items: center; gap: 10px; justify-content: center; flex-wrap: wrap; padding: 4px;
}
.name-row label { color: var(--text-dim); font-size: 0.95rem; }
.name-row input[type="text"] {
  background: rgba(0,0,0,0.4); border: 1px solid var(--card-border);
  color: var(--text); border-radius: 10px; padding: 8px 14px;
  font-family: inherit; font-size: 1rem; min-width: 160px;
}
.name-row input[type="text"]:focus { outline: none; border-color: var(--accent); }

/* Leaderboard */
.leaderboard-section {
  margin-top: 18px; padding-top: 14px;
  border-top: 1px dashed var(--card-border);
}
.leaderboard-section h3 {
  font-size: 0.92rem; color: var(--accent); text-align: center;
  letter-spacing: 0.06em; text-transform: uppercase;
  margin-bottom: 10px; font-weight: 800;
}
.leaderboard {
  width: 100%; border-collapse: collapse; font-size: 0.88rem;
  font-variant-numeric: tabular-nums;
}
.leaderboard th {
  text-align: left; padding: 6px 8px; color: var(--text-dim);
  font-weight: 700; font-size: 0.75rem; text-transform: uppercase;
  letter-spacing: 0.05em; border-bottom: 1px solid var(--card-border);
}
.leaderboard td { padding: 7px 8px; border-bottom: 1px solid rgba(255,255,255,0.04); }
.leaderboard td:nth-child(1) { color: var(--text-dim); width: 1.5em; }
.leaderboard td:nth-child(3) { color: var(--accent); font-weight: 700; }
.leaderboard td:nth-child(4) { color: var(--text-dim); }
.leaderboard tr.highlight { background: linear-gradient(90deg, rgba(0,240,255,0.12), rgba(255,69,230,0.12)); }
.leaderboard-empty {
  color: var(--text-dim); font-style: italic; font-size: 0.92rem;
  text-align: center; padding: 12px;
}

.result-card { text-align: center; padding: 12px; }
.result-emoji { font-size: 3.5rem; margin-bottom: 6px; }
.result-card h2 { font-size: 1.5rem; color: var(--accent); margin-bottom: 6px; }
.result-card .sub { color: var(--text-dim); font-size: 0.95rem; margin-top: 4px; }

/* Timer */
.timer {
  text-align: center;
  font-size: 2.4rem; font-weight: 800;
  color: var(--accent-3);
  text-shadow: 0 0 18px rgba(255, 215, 0, 0.5);
  font-variant-numeric: tabular-nums;
}
.timer.urgent { color: var(--wrong); animation: pulse 0.5s infinite alternate; }
@keyframes pulse { from { opacity: 1; } to { opacity: 0.6; } }

#confetti-canvas {
  position: fixed; top: 0; left: 0; width: 100vw; height: 100vh;
  pointer-events: none; z-index: 100;
}

@media (max-width: 480px) {
  h1 { font-size: 1.9rem; }
  .planets-grid { grid-template-columns: repeat(3, 1fr); }
  .problem { font-size: 2.4rem; }
  .choice { font-size: 1.4rem; padding: 14px; }
  .timer { font-size: 2rem; }
  .game-content { padding: 16px 14px; }
}