: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);
  }
}