:root {
  --background: #f0f8ff; /* AliceBlue for a playful vibe */
  --foreground: #334155;
  --primary: #0ea5e9;
  --primary-hover: #0284c7;
  --surface: #ffffff;
  --border: #e2e8f0;
  --error: #ef4444;
  --radius-lg: 16px;
  --radius-md: 12px;
  --shadow-sm: 0 4px 6px -1px rgba(0,0,0,0.05);
  --shadow-md: 0 10px 25px -5px rgba(0,0,0,0.1);
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #0f172a;
    --foreground: #f8fafc;
    --primary: #38bdf8;
    --primary-hover: #7dd3fc;
    --surface: #1e293b;
    --border: #334155;
  }
}

html, body {
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: var(--font-geist-sans), Arial, Helvetica, sans-serif;
  background: var(--background);
  color: var(--foreground);
  -webkit-font-smoothing: antialiased;
}

*, *::before, *::after {
  box-sizing: inherit;
}

/* Utilities */
.container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 1rem;
}

.card {
  background: var(--surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: 2.5rem 2rem;
  width: 100%;
  max-width: 400px;
  text-align: center;
  border: 1px solid var(--border);
}

.title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.subtitle {
  color: var(--foreground);
  opacity: 0.7;
  margin-bottom: 2rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.input {
  padding: 0.875rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: var(--background);
  color: var(--foreground);
  font-size: 1rem;
  outline: none;
  transition: var(--transition);
}

.input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.2);
}

.btn {
  background: var(--primary);
  color: #fff;
  font-weight: 600;
  font-size: 1rem;
  padding: 0.875rem 1.5rem;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: var(--transition);
}

.btn:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(1px);
}

.error-text {
  color: var(--error);
  font-size: 0.875rem;
  margin-top: -0.5rem;
}

.loader {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  font-size: 1.25rem;
  color: var(--primary);
}