:root {
  --bg: #0b0f1a;
  --bg-2: #121a2e;
  --panel: #161e33;
  --panel-2: #1d2740;
  --text: #eaf0ff;
  --muted: #8d9bc0;
  --line: #283355;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.55);

  /* category colors */
  --c-nonmetal: #4cc9f0;
  --c-noble-gas: #b794f6;
  --c-alkali-metal: #ff6b6b;
  --c-alkaline-earth-metal: #ffa94d;
  --c-metalloid: #38d9a9;
  --c-post-transition-metal: #74c0fc;
  --c-transition-metal: #ffd43b;
  --c-lanthanide: #f783ac;
  --c-actinide: #e599f7;
  --c-unknown: #94a3b8;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background:
    radial-gradient(1200px 600px at 80% -10%, #1b2b4a 0%, transparent 60%),
    radial-gradient(900px 500px at 0% 0%, #1a2340 0%, transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: "Outfit", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ---------- Header ---------- */
.site-header {
  padding: 28px clamp(16px, 4vw, 48px) 14px;
  text-align: center;
}
.header-inner h1 {
  margin: 0;
  font-weight: 800;
  font-size: clamp(1.5rem, 3.4vw, 2.6rem);
  letter-spacing: -0.02em;
  background: linear-gradient(95deg, #7cd4ff, #b794f6 45%, #ff9aa2);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.tagline {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: clamp(0.85rem, 1.6vw, 1.02rem);
}

/* ---------- Legend ---------- */
.legend {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-top: 18px;
}
.legend button {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
  color: var(--muted);
  font-family: inherit;
  font-size: 0.78rem;
  cursor: pointer;
  transition: all 0.18s;
}
.legend button:hover { color: var(--text); border-color: var(--muted); }
.legend button.active { color: #0b0f1a; font-weight: 600; }
.legend .dot {
  width: 11px;
  height: 11px;
  border-radius: 3px;
  flex: 0 0 auto;
}

/* ---------- Table ---------- */
main { flex: 1; }
.table-scroll {
  overflow-x: auto;
  padding: 12px clamp(12px, 3vw, 40px) 24px;
}
.periodic-table {
  display: grid;
  grid-template-columns: repeat(18, minmax(38px, 1fr));
  grid-auto-rows: minmax(38px, auto);
  gap: 5px;
  width: 100%;
  min-width: 880px;
  max-width: 1320px;
  margin: 0 auto;
}

.cell {
  position: relative;
  aspect-ratio: 1 / 1;
  border-radius: 8px;
  border: 1px solid var(--cat-color, var(--line));
  background:
    linear-gradient(160deg, color-mix(in srgb, var(--cat-color) 26%, var(--panel)) 0%,
                            color-mix(in srgb, var(--cat-color) 8%, var(--panel)) 100%);
  color: var(--text);
  cursor: pointer;
  padding: 4px 5px;
  overflow: hidden;
  transition: transform 0.14s ease, box-shadow 0.14s ease, opacity 0.2s, filter 0.2s;
  text-align: left;
  font-family: inherit;
}
.cell:hover {
  transform: translateY(-3px) scale(1.05);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--cat-color);
  z-index: 5;
}
.cell .num {
  font-size: 0.55rem;
  color: var(--muted);
  line-height: 1;
}
.cell .sym {
  position: absolute;
  left: 0; right: 0;
  top: 50%;
  transform: translateY(-50%);
  text-align: center;
  font-weight: 700;
  font-size: clamp(0.85rem, 1.5vw, 1.25rem);
}
.cell .nm {
  position: absolute;
  bottom: 3px;
  left: 0; right: 0;
  text-align: center;
  font-size: 0.44rem;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  padding: 0 2px;
}
.cell.dim { opacity: 0.16; filter: grayscale(0.6); }
.cell.match {
  box-shadow: 0 0 0 2px #fff, 0 0 22px var(--cat-color);
  transform: translateY(-2px) scale(1.04);
  z-index: 4;
}

/* f-block labels in the main body */
.placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px dashed var(--line);
  border-radius: 8px;
  color: var(--muted);
  font-size: 0.5rem;
  text-align: center;
  aspect-ratio: 1 / 1;
  line-height: 1.2;
  padding: 3px;
}

/* ---------- Overlay / Modal ---------- */
.overlay {
  position: fixed;
  inset: 0;
  background: rgba(5, 8, 16, 0.72);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 50;
  animation: fade 0.22s ease;
}
.overlay[hidden] { display: none; }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }

.modal {
  position: relative;
  width: min(940px, 96vw);
  max-height: 92vh;
  overflow-y: auto;
  background: linear-gradient(180deg, var(--panel) 0%, var(--bg-2) 100%);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: var(--shadow);
  animation: pop 0.26s cubic-bezier(0.2, 0.9, 0.3, 1.2);
}
@keyframes pop { from { transform: scale(0.92) translateY(14px); opacity: 0; } to { transform: none; opacity: 1; } }

.close-btn {
  position: absolute;
  top: 14px; right: 16px;
  width: 38px; height: 38px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  font-size: 1.4rem;
  line-height: 1;
  cursor: pointer;
  z-index: 3;
  transition: background 0.18s, transform 0.18s;
}
.close-btn:hover { background: rgba(255, 255, 255, 0.12); transform: rotate(90deg); }

.modal-grid {
  display: grid;
  grid-template-columns: 1fr 1.1fr;
  gap: 0;
}

/* Left column */
.modal-left {
  padding: 30px 26px;
  border-right: 1px solid var(--line);
  background:
    radial-gradient(120% 120% at 50% 0%, color-mix(in srgb, var(--accent, #4cc9f0) 16%, transparent) 0%, transparent 55%);
}
.id-card { text-align: center; }
.id-top {
  display: flex;
  justify-content: space-between;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 500;
}
.id-symbol {
  font-size: 4.6rem;
  font-weight: 800;
  line-height: 1;
  margin: 6px 0 2px;
  color: var(--accent, #fff);
  text-shadow: 0 6px 30px color-mix(in srgb, var(--accent, #4cc9f0) 50%, transparent);
}
.id-name { font-size: 1.5rem; font-weight: 700; }
.id-cat {
  display: inline-block;
  margin-top: 10px;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: #0b0f1a;
  background: var(--accent, #4cc9f0);
}

.atom-stage { margin-top: 18px; text-align: center; }
#atom { width: 100%; max-width: 280px; height: auto; }
.atom-caption {
  margin-top: 4px;
  font-size: 0.72rem;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.natural-form {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  text-align: center;
}
.natural-form:empty { display: none; }
.nf-head {
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}
.nf-text {
  font-size: 0.92rem;
  line-height: 1.45;
  margin: 6px auto 4px;
  max-width: 30ch;
}
#molecule {
  width: 100%;
  max-width: 200px;
  height: 168px;
  margin: 2px auto 0;
}
.nf-formula {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--accent, #4cc9f0);
}

/* Right column */
.modal-right { padding: 30px 28px; }
.fun-fact {
  font-size: 1.06rem;
  line-height: 1.55;
  margin: 0 0 20px;
  padding: 14px 16px;
  border-radius: 14px;
  background: color-mix(in srgb, var(--accent, #4cc9f0) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent, #4cc9f0) 35%, transparent);
}
.fun-fact::before {
  content: "💡 ";
}
.extra-facts {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}
.extra-facts:empty { display: none; }
.xfact {
  display: flex;
  gap: 11px;
  align-items: flex-start;
}
.xicon {
  flex: 0 0 auto;
  font-size: 1.05rem;
  line-height: 1.4;
  width: 22px;
  text-align: center;
}
.xfact .xk {
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.xfact .xv { font-size: 0.95rem; line-height: 1.4; }

.props {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-bottom: 22px;
}
.prop {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
}
.prop.wide { grid-column: 1 / -1; }
.prop .k { font-size: 0.68rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.04em; }
.prop .v { font-size: 1rem; font-weight: 600; margin-top: 2px; }
.prop .v .sub { display: block; font-size: 0.72rem; font-weight: 400; color: var(--muted); margin-top: 2px; }
.prop .v .config { font-weight: 600; letter-spacing: 0.01em; word-break: break-word; }

/* Meltdown widget */
.meltdown {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px 16px 18px;
}
.meltdown-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}
.meltdown-head h3 { margin: 0; font-size: 0.98rem; }
.meltdown-head .hint { color: var(--muted); font-weight: 400; font-size: 0.72rem; margin-left: 4px; }
.state-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 5px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  font-size: 0.82rem;
  font-weight: 600;
}
.state-icon { font-size: 1rem; }

.beaker {
  position: relative;
  height: 130px;
  border: 2px solid var(--line);
  border-top: none;
  border-radius: 0 0 16px 16px;
  background: linear-gradient(180deg, rgba(76,201,240,0.04), rgba(76,201,240,0.01));
  overflow: hidden;
  margin-bottom: 14px;
}
.particles { position: absolute; inset: 0; }
.particle {
  position: absolute;
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--accent, #4cc9f0);
  box-shadow: 0 0 8px var(--accent, #4cc9f0);
}
.phase-line {
  position: absolute;
  left: 0; right: 0;
  height: 0;
  border-top: 1px dashed rgba(255,255,255,0.25);
  pointer-events: none;
}
.phase-line span {
  position: absolute;
  right: 6px;
  top: -8px;
  font-size: 0.6rem;
  color: var(--muted);
  background: var(--bg-2);
  padding: 0 4px;
}

.lattice-caption {
  text-align: center;
  font-size: 0.74rem;
  color: var(--muted);
  margin-bottom: 12px;
  min-height: 1em;
  transition: color 0.2s;
}
.lattice-caption b { color: var(--text); font-weight: 600; }

#temp-slider {
  width: 100%;
  -webkit-appearance: none;
  appearance: none;
  height: 8px;
  border-radius: 999px;
  background: linear-gradient(90deg, #4cc9f0 0%, #b794f6 45%, #ffa94d 72%, #ff6b6b 100%);
  outline: none;
  cursor: pointer;
}
#temp-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 22px; height: 22px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid #0b0f1a;
  box-shadow: 0 2px 8px rgba(0,0,0,0.5);
  cursor: grab;
}
#temp-slider::-moz-range-thumb {
  width: 22px; height: 22px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid #0b0f1a;
  cursor: grab;
}
.temp-readout {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-top: 8px;
}
#temp-value { font-size: 1.15rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.temp-sub { color: var(--muted); font-size: 0.78rem; }
.meltdown.no-data { opacity: 0.55; }
.meltdown.no-data .beaker, .meltdown.no-data #temp-slider { filter: grayscale(0.5); }

/* ---------- Footer ---------- */
.site-footer {
  padding: 16px 24px 28px;
  text-align: center;
  color: var(--text);
  font-size: 0.82rem;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.site-footer .muted { color: var(--muted); }
#discovery-note { min-height: 1em; }

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  .modal-grid { grid-template-columns: 1fr; }
  .modal-left { border-right: none; border-bottom: 1px solid var(--line); }
  .props { grid-template-columns: 1fr 1fr; }
}