:root {
  /* Color Palette - Dark Mode Default */
  --bg-app: #0f172a;
  --bg-surface: rgba(30, 41, 59, 0.7);
  --bg-glass: rgba(15, 23, 42, 0.6);
  
  --primary: #6366f1; /* Indigo 500 */
  --primary-glow: rgba(99, 102, 241, 0.4);
  --secondary: #ec4899; /* Pink 500 */
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  
  --border-subtle: rgba(148, 163, 184, 0.1);
  --radius-md: 12px;
  --radius-lg: 24px;
  
  --font-sans: 'Outfit', system-ui, -apple-system, sans-serif;
}

/* Reset & Base */
* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  background-color: var(--bg-app);
  color: var(--text-main);
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

/* Background Gradients */
body::before {
  content: '';
  position: fixed;
  top: -20%;
  left: -10%;
  width: 50%;
  height: 50%;
  background: radial-gradient(circle, var(--primary-glow), transparent 70%);
  filter: blur(80px);
  z-index: -1;
  animation: float 10s ease-in-out infinite alternate;
}

@keyframes float {
  0% { transform: translate(0, 0); }
  100% { transform: translate(20px, 40px); }
}

/* Typography */
h1, h2, h3 { font-weight: 600; letter-spacing: -0.02em; }
a { color: inherit; text-decoration: none; }

/* Layout */
.app-container {
  max-width: 600px; /* Mobile focused */
  margin: 0 auto;
  padding: 20px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Components */
.card {
  background: var(--bg-surface);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  background: var(--primary);
  color: white;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: transform 0.1s, box-shadow 0.2s;
}

.btn:active { transform: scale(0.98); }
.btn-secondary { background: rgba(255,255,255,0.1); }

.input-field {
  width: 100%;
  padding: 12px;
  border-radius: var(--radius-md);
  background: rgba(0,0,0,0.2);
  border: 1px solid var(--border-subtle);
  color: white;
  margin-bottom: 12px;
  font-family: inherit;
}
.input-field:focus { outline: 2px solid var(--primary); border-color: transparent; }

/* Navigation */
.nav-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-around;
  padding: 12px;
  z-index: 100;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  gap: 4px;
}
.nav-item.active { color: var(--primary); }
.nav-icon { font-size: 1.25rem; }

/* Utilities */
.text-center { text-align: center; }
.flex-row { display: flex; gap: 12px; align-items: center; }
.flex-col { display: flex; flex-direction: column; gap: 12px; }
.w-full { width: 100%; }
.mt-4 { margin-top: 1rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-nav { margin-bottom: 80px; } /* Spacing for fixed nav */