:root{--bg:#f7f8fa;--panel:#fff;--panel2:#eef2f5;--text:#20262e;--muted:#697386;--border:#d9e0e7;--accent:#2989b3;--accent2:#3a3939;--accentSoft:rgba(41,137,179,.12);--good:#1e7a4b;--warn:#986318;--bad:#a23b3b;--shadow:0 10px 30px rgba(20,30,40,.07)}
body.dark{--bg:#12171b;--panel:#1b2228;--panel2:#242d35;--text:#eff4f7;--muted:#a9b5bf;--border:#394650;--accent:#58b3d7;--accent2:#e1e7eb;--accentSoft:rgba(88,179,215,.15);--shadow:none}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;line-height:1.5}button,input,select{font:inherit}button{cursor:pointer}.container{width:min(1200px,calc(100% - 28px));margin:auto}.site-header{background:radial-gradient(circle at 10% 0,var(--accentSoft),transparent 38%),var(--panel);border-bottom:1px solid var(--border);padding:34px 0 26px}.header-row{display:flex;justify-content:space-between;gap:24px;align-items:flex-start}.eyebrow{text-transform:uppercase;letter-spacing:.06em;font-size:.78rem;font-weight:800;color:var(--accent);margin:0 0 7px}h1{font-size:clamp(1.9rem,4vw,3.1rem);line-height:1.06;margin:0 0 10px}h2{font-size:1.35rem;margin:0 0 10px}h3{font-size:1.05rem;margin:0 0 7px}p{margin-top:0}.subtitle,.muted{color:var(--muted)}.subtitle{max-width:820px;margin-bottom:0}.tabs{display:flex;gap:8px;flex-wrap:wrap;padding:20px 0 8px}.tab,.secondary-btn,.primary-btn{border-radius:var(--r-md,14px);padding:9px 14px;border:1px solid var(--border);font-weight:700}.tab,.secondary-btn{background:var(--panel);color:var(--text)}.tab.active,.primary-btn{background:var(--accent);border-color:var(--accent);color:#fff}.tab-panel{display:none;padding:15px 0 48px}.tab-panel.active{display:block}.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--r-lg,18px);padding:17px;box-shadow:var(--shadow)}.controls{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}.controls label>span{display:block;color:var(--muted);font-size:.86rem;margin-bottom:5px}select,input[type="text"],input[type="number"],input[type="range"]{width:100%}select,input[type="text"],input[type="number"]{padding:9px 11px;background:var(--bg);color:var(--text);border:1px solid var(--border);border-radius:var(--r-sm,10px)}.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin:14px 0}.stat{background:var(--panel);border:1px solid var(--border);border-radius:var(--r-md,14px);padding:14px}.stat small{display:block;color:var(--muted)}.stat strong{display:block;font-size:1.65rem;margin:2px 0}.badge{display:inline-block;border-radius:999px;background:var(--accentSoft);color:var(--accent);font-weight:800;font-size:.8rem;padding:5px 9px;margin:0 5px 5px 0}.grid2{display:grid;grid-template-columns:1fr 1fr;gap:15px}.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.action-row{display:flex;gap:9px;flex-wrap:wrap;margin-top:12px}.note{padding:13px 15px;border-left:4px solid var(--accent);background:var(--accentSoft);border-radius:var(--r-sm,10px)}.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:var(--r-md,14px)}table{width:100%;border-collapse:collapse;background:var(--panel)}th,td{padding:10px 12px;text-align:left;border-bottom:1px solid var(--border)}th{background:var(--panel2);font-size:.86rem}.section-head{margin-bottom:15px}.section-head p{color:var(--muted);margin:0}.feedback{font-weight:700;min-height:24px}.good{color:var(--good)}.warn{color:var(--warn)}.bad{color:var(--bad)}footer{border-top:1px solid var(--border);background:var(--panel);color:var(--muted);padding:24px 0}footer p{margin:0}@media(max-width:850px){.controls,.stats,.grid3{grid-template-columns:1fr 1fr}.grid2{grid-template-columns:1fr}.header-row{flex-direction:column}}@media(max-width:560px){.controls,.stats,.grid3{grid-template-columns:1fr}.container{width:min(100% - 18px,1200px)}.tabs{display:grid;grid-template-columns:1fr 1fr}.tab{width:100%}}

.hero-config{display:grid;grid-template-columns:280px 1fr;gap:15px}.periodic-mini{display:grid;grid-template-columns:repeat(18,1fr);grid-template-rows:repeat(9,31px);gap:2px;min-width:620px}.mini-el{border:1px solid var(--border);background:var(--panel);color:var(--text);border-radius:4px;padding:0;font-size:.62rem;font-weight:800}.mini-el:hover,.mini-el.active{background:var(--accent);color:#fff;border-color:var(--accent)}.mini-scroll{overflow-x:auto}.config-output{font-size:1.08rem;line-height:1.9;word-spacing:.16em}.config-output sup{font-size:.7em}.orbital-diagram{display:flex;flex-wrap:wrap;gap:14px;align-items:flex-end}.subshell{display:flex;flex-direction:column;gap:5px;align-items:center}.subshell-label{font-weight:800}.boxes{display:flex;gap:3px}.orbital-box{width:34px;height:39px;border:2px solid var(--text);border-top:0;display:flex;justify-content:center;align-items:flex-end;gap:1px;padding-bottom:2px;font-size:1.25rem}.spin-up{color:var(--accent)}.spin-dn{color:#8a63c9}body.dark .spin-dn{color:#b49bd5}.aufbau-grid{display:grid;grid-template-columns:repeat(7,1fr);gap:6px}.aufbau-cell{padding:8px;border-radius:var(--r-sm,10px);background:var(--panel2);text-align:center;font-weight:800}.aufbau-cell.current{background:var(--accent);color:white}.step-controls{display:grid;grid-template-columns:1fr auto auto;gap:10px;align-items:end}.step-electron{font-size:1.15rem;font-weight:800}.rule-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.ion-row{display:grid;grid-template-columns:1fr 130px auto;gap:10px;align-items:end}.exception-badge{background:rgba(152,99,24,.13);color:var(--warn)}.quiz-option{display:flex;gap:8px;margin:8px 0;align-items:flex-start}.quiz-option input{margin-top:5px}.build-orbitals{display:flex;gap:9px;flex-wrap:wrap}.build-box{width:50px;height:55px;border:2px solid var(--text);border-top:0;background:var(--panel);font-size:1.45rem}.build-box.correct{border-color:var(--good);background:rgba(30,122,75,.1)}.build-box.wrong{border-color:var(--bad);background:rgba(162,59,59,.1)}@media(max-width:780px){.hero-config{grid-template-columns:1fr}.rule-grid{grid-template-columns:1fr}.ion-row,.step-controls{grid-template-columns:1fr}}