:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --surface-soft: #f8fafc;
  --ink: #111827;
  --muted: #667085;
  --line: #e4e8f0;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --success: #149761;
  --success-soft: #e8f8ef;
  --danger: #d14343;
  --danger-soft: #fff0f0;
  --warning: #f59e0b;
  --shadow: 0 22px 60px rgba(16, 24, 40, 0.1);
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at 12% 0%, rgba(37, 99, 235, 0.12), transparent 24rem),
    radial-gradient(circle at 88% 14%, rgba(20, 151, 97, 0.1), transparent 20rem),
    linear-gradient(145deg, #fbfdff 0%, var(--bg) 48%, #eef3f9 100%);
}

button {
  border: 0;
  font: inherit;
  cursor: pointer;
}

.app-shell {
  width: min(1160px, 100%);
  min-height: 100vh;
  margin: 0 auto;
  padding: clamp(1rem, 4vw, 2.5rem);
}

.page {
  display: none;
  min-height: calc(100vh - clamp(2rem, 8vw, 5rem));
  animation: pageIn 360ms ease both;
}

.page.active {
  display: flex;
}

#startPage,
#countdownPage,
#resultPage {
  align-items: center;
  justify-content: center;
  text-align: center;
  flex-direction: column;
}

#memoryPage,
#challengePage {
  flex-direction: column;
  gap: 1.25rem;
}

#memoryPage {
  gap: 0.85rem;
}

h1,
h2,
p {
  margin: 0;
}

h1 {
  max-width: 760px;
  font-size: clamp(2.4rem, 7vw, 5rem);
  line-height: 1;
  font-weight: 900;
}

h2 {
  font-size: clamp(1.65rem, 4vw, 2.8rem);
  line-height: 1.05;
  font-weight: 900;
}

.subtitle {
  max-width: 640px;
  margin: 1rem 0 2rem;
  color: var(--muted);
  font-size: clamp(1rem, 3vw, 1.2rem);
  font-weight: 600;
  line-height: 1.55;
}

.eyebrow {
  margin-bottom: 0.45rem;
  color: var(--primary);
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0;
  text-transform: uppercase;
}

.brand-mark {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.38rem;
  width: 4.7rem;
  height: 4.7rem;
  margin-bottom: 1.4rem;
  padding: 0.8rem;
  border: 1px solid rgba(228, 232, 240, 0.9);
  border-radius: 1.1rem;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: var(--shadow);
}

.brand-mark span {
  border-radius: 0.22rem;
  background: var(--ink);
}

.brand-mark span:nth-child(2) {
  background: var(--primary);
}

.brand-mark span:nth-child(3) {
  background: var(--success);
}

.brand-mark span:nth-child(4) {
  background: var(--warning);
}

.primary-button,
.secondary-button {
  min-height: 3.35rem;
  padding: 0 1.45rem;
  border-radius: 0.7rem;
  font-weight: 900;
  transition:
    transform 180ms ease,
    box-shadow 180ms ease,
    background 180ms ease;
}

.primary-button {
  color: #fff;
  background: var(--primary);
  box-shadow: 0 14px 30px rgba(37, 99, 235, 0.24);
}

.secondary-button {
  color: var(--ink);
  background: #e9eef8;
}

.primary-button:hover,
.secondary-button:hover {
  transform: translateY(-2px);
}

.primary-button:active,
.secondary-button:active {
  transform: translateY(0);
}

.countdown-number {
  color: var(--primary);
  font-size: clamp(8rem, 34vw, 18rem);
  font-weight: 900;
  line-height: 1;
  animation: pulseNumber 900ms ease both;
}

.top-bar {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 1rem;
}

.timer-card {
  flex: 0 0 auto;
  min-width: 12rem;
  padding: 0.85rem 1rem;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  background: rgba(255, 255, 255, 0.86);
  box-shadow: 0 10px 28px rgba(16, 24, 40, 0.07);
  text-align: right;
}

.timer-card span {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

.timer-card strong {
  display: block;
  margin-top: 0.2rem;
  font-size: 1.35rem;
  font-weight: 900;
}

.qr-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: clamp(0.35rem, 1.2vw, 0.75rem);
  width: min(100%, 980px);
  margin: 0 auto;
}

.qr-tile,
.challenge-card,
.stat {
  border: 1px solid rgba(228, 232, 240, 0.95);
  background: rgba(255, 255, 255, 0.92);
  box-shadow: var(--shadow);
}

.qr-tile {
  min-width: 0;
  padding: clamp(0.28rem, 1vw, 0.55rem);
  border-radius: 0.65rem;
  animation: cardRise 420ms ease both;
}

.qr-visual {
  display: grid;
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  padding: 5%;
  overflow: hidden;
  border: 0;
  border-radius: 0.2rem;
  background: #fff;
}

.qr-module {
  border-radius: 0;
  background: transparent;
}

.qr-module.dark {
  background: #000;
}

.qr-tile strong {
  display: block;
  padding-top: 0.42rem;
  color: var(--ink);
  font-size: clamp(0.78rem, 1.6vw, 0.95rem);
  font-weight: 900;
  text-align: center;
}

.sticky-action {
  align-self: center;
  margin-top: auto;
}

.challenge-layout {
  display: grid;
  grid-template-columns: minmax(280px, 0.8fr) minmax(320px, 1fr);
  gap: clamp(1rem, 4vw, 2rem);
  align-items: center;
}

.challenge-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 0;
  padding: clamp(1rem, 4vw, 1.6rem);
  border-radius: 0.9rem;
}

.large-qr {
  width: min(62vw, 340px);
  max-width: 100%;
}

.answer-feedback {
  min-height: 1.45rem;
  margin-top: 1rem;
  font-weight: 900;
}

.answer-feedback.correct {
  color: var(--success);
}

.answer-feedback.incorrect {
  color: var(--danger);
}

.option-label {
  margin-bottom: 0.75rem;
  color: var(--muted);
  font-weight: 800;
}

.number-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 0.7rem;
}

.number-button {
  aspect-ratio: 1 / 1;
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 0.65rem;
  color: var(--ink);
  background: var(--surface);
  font-size: clamp(1.15rem, 4vw, 1.55rem);
  font-weight: 900;
  box-shadow: 0 12px 28px rgba(16, 24, 40, 0.07);
  transition:
    transform 150ms ease,
    border-color 150ms ease,
    background 150ms ease;
}

.number-button:hover {
  border-color: rgba(37, 99, 235, 0.45);
  transform: translateY(-2px);
}

.number-button.correct {
  border-color: rgba(20, 151, 97, 0.3);
  color: var(--success);
  background: var(--success-soft);
}

.number-button.incorrect {
  border-color: rgba(209, 67, 67, 0.32);
  color: var(--danger);
  background: var(--danger-soft);
}

.number-button:disabled {
  cursor: default;
}

.accuracy-ring {
  --accuracy: 0%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  place-items: center;
  position: relative;
  width: 11.5rem;
  aspect-ratio: 1 / 1;
  margin: 1.3rem 0;
  border-radius: 999px;
  background: conic-gradient(
    var(--primary) var(--accuracy),
    rgba(37, 99, 235, 0.12) 0
  );
  box-shadow: var(--shadow);
}

.accuracy-ring::before {
  position: absolute;
  inset: 0.75rem;
  border-radius: inherit;
  background: rgba(255, 255, 255, 0.96);
  content: "";
}

.accuracy-ring strong {
  position: relative;
  z-index: 1;
  font-size: 2.3rem;
  font-weight: 900;
  line-height: 1;
}

.accuracy-ring span {
  position: relative;
  z-index: 1;
  margin-top: 0.35rem;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 900;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.9rem;
  width: min(560px, 100%);
}

.stat {
  min-height: 7rem;
  padding: 1rem;
  border-radius: 0.8rem;
}

.stat span {
  display: block;
  min-height: 2.2rem;
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 800;
}

.stat strong {
  display: block;
  margin-top: 0.45rem;
  font-size: clamp(1.35rem, 5vw, 1.9rem);
  font-weight: 900;
}

.result-feedback {
  margin: 1.15rem 0 1.2rem;
  color: var(--muted);
  font-size: 1.08rem;
  font-weight: 900;
}

.result-feedback.master {
  color: var(--success);
}

.result-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
}

@keyframes pageIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulseNumber {
  0% {
    opacity: 0;
    transform: scale(0.84);
  }

  55% {
    opacity: 1;
    transform: scale(1.05);
  }

  100% {
    opacity: 0.96;
    transform: scale(1);
  }
}

@keyframes cardRise {
  from {
    opacity: 0;
    transform: translateY(16px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .qr-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

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

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

  .timer-card {
    width: 100%;
    text-align: left;
  }
}

@media (max-width: 520px) {
  .app-shell {
    padding: 1rem;
  }

  .number-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 0.45rem;
  }

  .number-button {
    border-radius: 0.55rem;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .primary-button,
  .secondary-button {
    width: 100%;
  }
}

.site-header {
  width: min(1160px, 100%);
  margin: 0 auto;
  padding: 1rem clamp(1rem, 4vw, 2.5rem) 0;
}

.home-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.1rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.9);
  box-shadow: 0 10px 24px rgba(16, 24, 40, 0.08);
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 800;
  text-decoration: none;
  transition:
    transform 160ms ease,
    box-shadow 160ms ease;
}

.home-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 30px rgba(16, 24, 40, 0.12);
}

a.secondary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
}

.page {
  min-height: calc(100vh - clamp(2rem, 8vw, 5rem) - 3.6rem);
}