/* M2: Element masses and isotope details. */
#periodic-table{grid-template-columns:34px repeat(var(--columns),minmax(64px,1fr))}
.element{padding:18px 2px 15px;touch-action:manipulation;color:#182c42}
.element:hover,.element:active{background:var(--color)}
.element:focus-visible{z-index:1;outline:3px solid #1c4f7e;outline-offset:1px}
.element .atomic-mass{position:absolute;left:4px;top:4px;font-size:11px;font-weight:400;line-height:1.2;white-space:nowrap;font-variant-numeric:tabular-nums}
.element-tooltip{position:fixed;z-index:30;background:#183c60;color:white;padding:12px 16px;border-radius:7px;box-shadow:0 6px 24px #183c6030;pointer-events:none;max-width:calc(100vw - 16px)}
.element-tooltip strong,.element-tooltip span{display:block}.element-tooltip strong{font-size:18px}.element-tooltip span{font-size:13px;color:#d1e2f2;margin-top:4px}
.isotope-panel{background:#fff;color:#182c42;border:1px solid #b6c9dd;border-radius:12px;box-shadow:0 16px 70px #0e2e5140;padding:22px;width:620px;max-width:calc(100vw - 24px);max-height:calc(100dvh - 24px);overflow-y:auto}
.held-panel{position:fixed;z-index:40;pointer-events:none}
.detail-dialog{margin:auto}.detail-dialog::backdrop{background:#142e4a66;backdrop-filter:blur(2px)}
.detail-header{display:flex;gap:16px;justify-content:space-between;align-items:flex-start}.detail-header h2{font-size:25px;margin:0}.detail-header p{font-size:14px;color:#5c7288;margin:5px 0 0}.detail-header button{font-size:14px;padding:8px 12px}
.detail-mass{font-size:14px;background:#edf3f9;border-radius:5px;padding:10px 12px;margin:16px 0}
.isotope-panel h3{font-size:15px;margin:18px 0 12px;font-weight:600}
.isotope-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}
.isotope-item{display:flex;align-items:center;gap:14px;border:1px solid #d5e0ea;border-radius:7px;padding:12px;min-height:78px}
.nuclide{display:grid;grid-template-columns:minmax(24px,auto) auto;grid-template-rows:1fr 1fr;column-gap:3px;align-items:center;flex-shrink:0}.nuclide sup,.nuclide sub{font-size:13px;line-height:1.2;position:static;text-align:right}.nuclide sup{grid-column:1;grid-row:1;align-self:start}.nuclide sub{grid-column:1;grid-row:2;align-self:end}.nuclide strong{grid-column:2;grid-row:1 / 3;font-size:29px;font-weight:650;line-height:1.2}
.isotope-values{display:flex;flex-direction:column;gap:4px;min-width:0}.isotope-values>strong{font-size:14px;font-weight:600;overflow-wrap:anywhere}.trace-badge{font-size:12px;color:#685318;background:#fff2c6;border-radius:3px;padding:2px 5px;align-self:flex-start}.stability{font-size:12px;color:#5c7288}
.coverage-note,.detail-explanation,.detail-hint{font-size:12px;color:#5c7288;line-height:1.5}.coverage-note{border-top:1px solid #e0e8f0;padding-top:12px;margin-top:16px}.detail-hint{margin-bottom:0}
.source-links{display:flex;flex-wrap:wrap;gap:6px 14px;margin-top:12px}.source-links a{font-size:12px;color:#215f94;text-underline-offset:2px}
@media(max-width:520px){.isotope-panel{padding:16px}.isotope-grid{grid-template-columns:1fr}.held-panel .isotope-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.isotope-item{min-height:72px}}
@media print{.element-tooltip,.isotope-panel{display:none!important}#periodic-table{grid-template-columns:20px repeat(var(--columns),minmax(0,1fr))}.element{height:45px;padding:12px 0 10px}.element .atomic-mass{font-size:7px;left:2px;top:2px}}