:root {
  --color-page: #f6f8fb;
  --color-surface: #ffffff;
  --color-text: #172033;
  --color-muted: #647086;
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-secondary: #e8eefc;
  --color-border: #d8e0ed;
  --color-success: #15803d;
  --color-success-bg: #dcfce7;
  --color-danger: #b91c1c;
  --color-danger-bg: #fee2e2;
  --shadow-card: 0 20px 60px rgba(23, 32, 51, 0.12);
  --radius: 8px;
  --space: clamp(1rem, 3vw, 1.5rem);
  --focus-ring: 0 0 0 4px rgba(37, 99, 235, 0.18);
}

* {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  margin: 0;
  background:
    radial-gradient(circle at top left, rgba(37, 99, 235, 0.13), transparent 30rem),
    var(--color-page);
  color: var(--color-text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

button,
input {
  font: inherit;
}

.app-shell {
  width: min(100%, 600px);
  min-height: 100vh;
  margin: 0 auto;
  padding: clamp(1rem, 4vw, 2rem);
  display: grid;
  align-items: center;
}

.screen {
  position: relative;
  width: 100%;
  padding: clamp(1.25rem, 5vw, 2rem);
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid rgba(216, 224, 237, 0.9);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 180ms ease, transform 180ms ease;
}

.screen-active {
  opacity: 1;
  transform: translateY(0);
}

[hidden] {
  display: none !important;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0.75rem;
  font-size: clamp(2rem, 8vw, 3.25rem);
  line-height: 1.05;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 1.5rem;
  font-size: clamp(1.45rem, 6vw, 2rem);
  line-height: 1.18;
  letter-spacing: 0;
}

.eyebrow,
.question-kicker,
.progress-label {
  margin-bottom: 0.5rem;
  color: var(--color-primary);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.description {
  margin-bottom: 1.5rem;
  color: var(--color-muted);
  font-size: 1.05rem;
}

.mode-picker {
  display: grid;
  gap: 0.8rem;
  margin: 0 0 1.25rem;
  padding: 0;
  border: 0;
}

.mode-picker legend {
  margin-bottom: 0.75rem;
  color: var(--color-text);
  font-weight: 800;
}

.mode-option {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.8rem;
  align-items: center;
  min-height: 72px;
  padding: 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  cursor: pointer;
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.mode-option:has(input:checked) {
  border-color: var(--color-primary);
  box-shadow: var(--focus-ring);
}

.mode-option:active {
  transform: scale(0.99);
}

.mode-option input {
  width: 1.2rem;
  height: 1.2rem;
  accent-color: var(--color-primary);
}

.mode-option strong,
.mode-option small {
  display: block;
}

.mode-option small {
  color: var(--color-muted);
}

.button,
.choice-button {
  width: 100%;
  min-height: 52px;
  border: 0;
  border-radius: var(--radius);
  font-weight: 800;
  cursor: pointer;
  transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease, transform 120ms ease;
}

.button:focus-visible,
.choice-button:focus-visible,
.typing-input:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.button:active,
.choice-button:active {
  transform: scale(0.99);
}

.button-primary {
  background: var(--color-primary);
  color: white;
}

.button-primary:hover {
  background: var(--color-primary-dark);
}

.button-secondary {
  margin-top: 1rem;
  background: var(--color-secondary);
  color: var(--color-primary-dark);
}

.quiz-header {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1rem;
  align-items: start;
  margin-bottom: 1.5rem;
}

.progress-track {
  width: 100%;
  height: 0.65rem;
  overflow: hidden;
  border-radius: 999px;
  background: #dfe7f4;
}

.progress-bar {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #2563eb, #14b8a6);
  transition: width 260ms ease;
}

.score-pill {
  min-width: 84px;
  margin: 0;
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
  background: #eef6ff;
  color: var(--color-primary-dark);
  font-size: 0.86rem;
  font-weight: 800;
  text-align: center;
}

.question-card {
  min-height: 330px;
}

.question-card.is-changing {
  animation: questionFade 180ms ease;
}

.answer-area {
  display: grid;
  gap: 0.75rem;
}

.choice-button {
  padding: 0.9rem 1rem;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  text-align: left;
}

.choice-button:hover:not(:disabled) {
  border-color: var(--color-primary);
  background: #f8fbff;
}

.choice-button.is-correct {
  border-color: var(--color-success);
  background: var(--color-success-bg);
  color: var(--color-success);
}

.choice-button.is-incorrect {
  border-color: var(--color-danger);
  background: var(--color-danger-bg);
  color: var(--color-danger);
}

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

.typing-form {
  display: grid;
  gap: 0.75rem;
}

.typing-input {
  width: 100%;
  min-height: 54px;
  padding: 0.9rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  color: var(--color-text);
}

.feedback-message {
  min-height: 1.6rem;
  margin: 1rem 0 0;
  color: var(--color-muted);
  font-weight: 700;
}

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

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

.final-score {
  margin-bottom: 0;
  font-size: clamp(3rem, 16vw, 5rem);
  font-weight: 900;
  line-height: 1;
}

.final-percentage {
  margin-bottom: 1rem;
  color: var(--color-primary);
  font-size: 1.5rem;
  font-weight: 900;
}

.loader {
  width: 3rem;
  height: 3rem;
  margin: 0 auto 1rem;
  border: 0.35rem solid #dbe5f3;
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 800ms linear infinite;
}

.confetti-canvas {
  position: fixed;
  inset: 0;
  z-index: 20;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

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

@keyframes questionFade {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

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

@media (max-width: 430px) {
  .app-shell {
    align-items: stretch;
    padding: 0;
  }

  .screen {
    min-height: 100vh;
    border-width: 0;
    border-radius: 0;
    box-shadow: none;
  }

  .quiz-header {
    grid-template-columns: 1fr;
  }

  .score-pill {
    width: max-content;
  }
}