:root {
  --bg: #FFF8E7;
  --primary: #FF6B35;
  --primary-dark: #E55A2B;
  --secondary: #4ECDC4;
  --secondary-dark: #3DBDB4;
  --correct: #2ECC71;
  --incorrect: #E74C3C;
  --text: #2C3E50;
  --text-light: #7F8C8D;
  --white: #FFFFFF;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  --radius: 16px;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
}

body {
  font-family: 'Nunito', sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 600px;
  margin: 0 auto;
  padding: 16px;
}

.title {
  font-size: 2.5rem;
  font-weight: 900;
  text-align: center;
  color: var(--primary);
  margin-bottom: 8px;
}

.subtitle {
  text-align: center;
  font-size: 1.2rem;
  color: var(--text-light);
  margin-bottom: 24px;
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  border: none;
  border-radius: var(--radius);
  font-family: 'Nunito', sans-serif;
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.1s, box-shadow 0.1s;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.btn:active {
  transform: scale(0.96);
}

.btn-primary {
  background: var(--primary);
  color: var(--white);
  box-shadow: 0 4px 0 var(--primary-dark);
}

.btn-primary:active {
  box-shadow: 0 2px 0 var(--primary-dark);
  transform: translateY(2px);
}

.btn-secondary {
  background: var(--secondary);
  color: var(--white);
  box-shadow: 0 4px 0 var(--secondary-dark);
}

.btn-secondary:active {
  box-shadow: 0 2px 0 var(--secondary-dark);
  transform: translateY(2px);
}

.btn-large {
  font-size: 1.5rem;
  padding: 18px 48px;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
}

.screen {
  display: none;
  min-height: 100vh;
  padding-top: 20px;
  padding-bottom: env(safe-area-inset-bottom, 20px);
}

.screen.active {
  display: block;
}