:root {
  --bg: #0f1221;
  --card-bg: #141936;
  --text: #e8ebf7;
  --muted: #a7b0c4;
  --ring: rgba(255, 255, 255, .12);

  /* Category palette */
  --alkali-metal: 5 78% 63%;
  --alkaline-earth-metal: 33 88% 60%;
  --transition-metal: 220 70% 56%;
  --post-transition-metal: 205 28% 65%;
  --metalloid: 165 55% 50%;
  --other-nonmetal: 140 55% 45%;
  --halogen: 90 72% 55%;
  --noble-gas: 268 85% 60%;
  --lanthanide: 280 62% 62%;
  --actinide: 320 62% 60%;
  --unknown: 220 10% 60%;

  --radius-2xl: 1.25rem;
  --radius-xl: .875rem;
  --shadow-elev: 0 10px 30px rgba(0, 0, 0, .35), 0 2px 8px rgba(0, 0, 0, .25);
}

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

html,
body {
  height: 100%;
  width: 100%
}

body {
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  background:
    radial-gradient(60rem 60rem at 10% -20%, hsl(var(--noble-gas)/.15), transparent 60%),
    radial-gradient(60rem 60rem at 110% 120%, hsl(var(--transition-metal)/.12), transparent 60%),
    var(--bg);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  min-height: 100dvh;
  min-height: 100svh;
  overflow: hidden;
}

.container {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  padding: max(1rem, env(safe-area-inset-top)) max(1rem, env(safe-area-inset-right)) max(1rem, env(safe-area-inset-bottom)) max(1rem, env(safe-area-inset-left));
}

.element {
  --accent: var(--noble-gas);
  width: 320px;
  height: 320px;
  background:
    linear-gradient(145deg, hsl(var(--accent)/0.18) 0%, hsl(var(--accent)/0.1) 100%),
    var(--card-bg);
  border: 1px solid var(--ring);
  border-radius: var(--radius-2xl);
  box-shadow: var(--shadow-elev);
  display: grid;
  grid-template-rows: 1fr auto;
  padding: 1rem;
  position: relative;
  overflow: hidden;
  transition: transform .2s ease, box-shadow .2s ease;
  isolation: isolate;
  backdrop-filter: blur(4px) brightness(0.95);
}

.element:hover {
  transform: translateY(-2px) scale(1.01);
  box-shadow: 0 14px 40px rgba(0, 0, 0, .45), 0 3px 10px rgba(0, 0, 0, .22);
}

.atomic-number {
  position: absolute;
  top: 1rem;
  left: 1rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  font-size: 1.25rem;
}

.symbol {
  align-self: center;
  justify-self: center;
  font-size: 5rem;
  font-weight: 800;
  letter-spacing: -.02em;
  line-height: 1;
  text-shadow: 0 4px 10px rgba(0, 0, 0, .4);
  z-index: 1;
  color: var(--text);
}

figcaption {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: end;
  gap: .5rem;
  z-index: 1;
}

.name {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
}

.mass {
  font-variant-numeric: tabular-nums;
  color: var(--text);
  font-size: 0.95rem;
}

/* Category hooks */
.alkali-metal {
  --accent: var(--alkali-metal);
}

.alkaline-earth-metal {
  --accent: var(--alkaline-earth-metal);
}

.transition-metal {
  --accent: var(--transition-metal);
}

.post-transition-metal {
  --accent: var(--post-transition-metal);
}

.metalloid {
  --accent: var(--metalloid);
}

.other-nonmetal {
  --accent: var(--other-nonmetal);
}

.halogen {
  --accent: var(--halogen);
}

.noble-gas {
  --accent: var(--noble-gas);
}

.lanthanide {
  --accent: var(--lanthanide);
}

.actinide {
  --accent: var(--actinide);
}

.unknown {
  --accent: var(--unknown);
}

/* Optional shorthand */
.alkali {
  --accent: var(--alkali-metal);
}

.alkaline-earth {
  --accent: var(--alkaline-earth-metal);
}

.transition {
  --accent: var(--transition-metal);
}

.post-transition {
  --accent: var(--post-transition-metal);
}

/* Ensure proper centering and scaling on small screens */
@media (max-height: 400px),
(max-width: 350px) {
  .element {
    transform: scale(0.85);
  }
}

footer {
  position: fixed;
  left: 0;
  bottom: 0;
  width: 100vw;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 120px;
  z-index: 10;
  box-shadow: 0 -2px 12px rgba(0, 0, 0, 0.07);
}

@media (max-width: 600px) {
  footer {
    height: auto;
    padding: 0.5rem 0;
  }
}