:root {
  --background: 42 60% 97%;
  --foreground: 152 30% 16%;
  --primary: 142 72% 34%;
  --secondary: 18 92% 58%;
  --muted: 45 36% 90%;
  --destructive: 0 72% 55%;
  --border: 38 26% 82%;
  --card: 0 0% 100%;

  --shadow-sm: 0 6px 18px hsla(152, 30%, 16%, 0.06);
  --shadow-md: 0 14px 34px hsla(152, 30%, 16%, 0.1);
  --shadow-lg: 0 24px 60px hsla(152, 30%, 16%, 0.14);

  --transition-fast: 160ms ease;
  --transition-smooth: 320ms cubic-bezier(0.2, 0.8, 0.2, 1);

  --radius-sm: 0.75rem;
  --radius-md: 1.1rem;
  --radius-lg: 1.6rem;
}

.dark {
  --background: 155 28% 10%;
  --foreground: 42 45% 94%;
  --primary: 142 68% 48%;
  --secondary: 20 92% 62%;
  --muted: 155 18% 18%;
  --destructive: 0 72% 58%;
  --border: 155 14% 24%;
  --card: 155 24% 14%;

  --shadow-sm: 0 6px 18px hsla(0, 0%, 0%, 0.2);
  --shadow-md: 0 14px 34px hsla(0, 0%, 0%, 0.28);
  --shadow-lg: 0 24px 60px hsla(0, 0%, 0%, 0.38);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at top left, hsla(18, 92%, 58%, 0.08), transparent 28%),
    radial-gradient(circle at top right, hsla(142, 72%, 34%, 0.12), transparent 34%),
    hsl(var(--background));
  min-height: 100vh;
}

#root {
  min-height: 100vh;
}

.card-surface {
  background: hsl(var(--card));
  border: 1px solid hsl(var(--border));
  box-shadow: var(--shadow-md);
}

.soft-ring:focus-visible {
  outline: none;
  box-shadow: 0 0 0 4px hsla(142, 72%, 34%, 0.18);
}

.glass-panel {
  background: linear-gradient(180deg, hsla(0, 0%, 100%, 0.82), hsla(0, 0%, 100%, 0.68));
  backdrop-filter: blur(18px);
}

.dark .glass-panel {
  background: linear-gradient(180deg, hsla(155, 24%, 16%, 0.92), hsla(155, 24%, 14%, 0.82));
}

.hero-grid {
  background-image:
    linear-gradient(hsla(var(--border), 0.35) 1px, transparent 1px),
    linear-gradient(90deg, hsla(var(--border), 0.35) 1px, transparent 1px);
  background-size: 22px 22px;
}

.lesson-option {
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
}

.lesson-option:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.pulse-dot {
  animation: pulseDot 1.8s infinite;
}

@keyframes pulseDot {
  0% { transform: scale(0.9); opacity: 0.55; }
  50% { transform: scale(1.08); opacity: 1; }
  100% { transform: scale(0.9); opacity: 0.55; }
}

.slide-in {
  animation: slideIn 320ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.skeleton {
  background: linear-gradient(90deg, hsla(var(--muted), 1) 25%, hsla(var(--border), 0.8) 37%, hsla(var(--muted), 1) 63%);
  background-size: 400% 100%;
  animation: shimmer 1.4s ease infinite;
}

@keyframes shimmer {
  0% { background-position: 100% 0; }
  100% { background-position: 0 0; }
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input,
select {
  font: inherit;
}