@font-face{font-family:LabKorean;src:url(../assets/noto-sans-kr-korean-400-normal-CmjJz_gz.woff2) format('woff2');font-weight:400;font-display:swap}
@font-face{font-family:LabKorean;src:url(../assets/noto-sans-kr-korean-700-normal-DvnDzSjd.woff2) format('woff2');font-weight:700;font-display:swap}
:root{color-scheme:light;--bg:#f3f6f5;--surface:#fff;--soft:#eaf2ef;--ink:#1a2926;--muted:#526b63;--line:#d5e1db;--accent:#176f65;--accent-ink:#fff;--plot:#f6faf8;--grid:#dce8e1;--focus:#976622;--wrong:#934337;--right:#176e4e;font-family:LabKorean,'Noto Sans KR','Apple SD Gothic Neo',system-ui,sans-serif;font-synthesis:none}
html[data-theme=night]{color-scheme:dark;--bg:#172622;--surface:#20352f;--soft:#29443b;--ink:#edf3ee;--muted:#b8cdc2;--line:#3f5a4d;--accent:#9bd9c6;--accent-ink:#152a22;--plot:#192d25;--grid:#395145;--focus:#edc88b;--wrong:#f5b9ae;--right:#a9e4c2}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:86px}
body{margin:0;background:var(--bg);color:var(--ink);font-size:15px;line-height:1.75;letter-spacing:-.025em}
button,input{font:inherit}button,a,input{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default}
a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}
button:focus-visible,a:focus-visible,summary:focus-visible,[tabindex]:focus-visible,input:focus-visible{outline:3px solid var(--focus);outline-offset:4px}
h1,h2,h3,p{margin:0}h1,h2,h3{font-weight:700;line-height:1.45;word-break:keep-all}
h1{font-size:28px;letter-spacing:-.035em}h2{font-size:20px;letter-spacing:-.025em}h3{font-size:17px}
p{word-break:keep-all;overflow-wrap:anywhere}[hidden]{display:none!important}
.skip-link{position:fixed;left:16px;top:8px;z-index:100;background:var(--surface);padding:10px 20px;transform:translateY(-160%)}
.skip-link:focus{transform:translateY(0)}
.site-header{position:sticky;top:0;z-index:10;border-bottom:1px solid var(--line);background:var(--bg)}
.header-inner{max-width:1060px;margin:auto;padding:14px 24px;display:flex;justify-content:space-between;align-items:center;gap:16px}
.brand{display:flex;gap:10px;align-items:center;white-space:nowrap}.brand strong{font-size:16px}.brand span{font-size:10px;letter-spacing:.06em;color:var(--muted)}
.header-inner nav{display:flex;align-items:center;gap:20px;font-size:12px}
.theme-toggle{border:1px solid var(--line);border-radius:20px;min-height:36px;padding:4px 12px;background:var(--surface);color:var(--ink);white-space:nowrap;font-size:12px}
.section,.site-footer{width:min(940px,calc(100% - 48px));margin-inline:auto}
.section{padding:28px 0}
.hero{padding:44px 0 34px}
.hero-copy{max-width:760px}
.hero p{margin-top:18px;color:var(--muted);font-size:16px;line-height:1.95}
.hero .button{margin-top:22px}
.button{display:inline-flex;gap:12px;justify-content:center;align-items:center;min-height:44px;padding:9px 17px;border-radius:7px;border:1px solid transparent;font-size:13px;font-weight:700;line-height:1.6}
.button.primary{background:var(--accent);color:var(--accent-ink)}.button.primary:hover{filter:brightness(.94);text-decoration:none}
.button.quiet{background:transparent;color:var(--accent);border-color:var(--line)}.button:disabled{background:var(--line);color:var(--muted)}
.section-heading{display:flex;align-items:baseline;justify-content:space-between;gap:16px;margin-bottom:14px}
.section-heading>span{font-size:12px;color:var(--muted)}
.section-link{font-size:12px;white-space:nowrap}
.section-intro{max-width:760px;margin:-2px 0 20px;color:var(--muted);font-size:14px;line-height:1.85}
.demo-section{padding-top:30px}
.demo-shell{border:1px solid var(--line);border-radius:12px;background:var(--surface);overflow:hidden}
.demo-tabs{display:flex;border-bottom:1px solid var(--line);background:var(--soft)}
.demo-tabs button{display:flex;align-items:center;gap:10px;min-height:52px;padding:10px 22px;border:0;border-bottom:2px solid transparent;background:transparent;color:var(--muted);line-height:1.6}
.demo-tabs strong{font-size:15px}.demo-tabs span{font-size:12px}
.demo-tabs button[aria-selected=true]{background:var(--surface);color:var(--accent);border-bottom-color:var(--accent)}
.demo-panel{padding:22px}
.lab-grid{display:grid;grid-template-columns:minmax(0,1.85fr) minmax(0,1fr);gap:26px;align-items:start}
.lab-visual,.lab-notes{min-width:0}
.segmented{display:flex;gap:6px;flex-wrap:wrap}
.segmented button,.question-picker button{background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:7px 14px;min-height:40px;color:var(--ink);font-size:13px}
.segmented button[aria-pressed=true],.question-picker button[aria-pressed=true]{background:var(--soft);border-color:var(--accent);color:var(--accent);font-weight:700}
.compact{justify-content:center}.compact button{font-size:12px;padding:5px 12px;min-height:36px}
.model-readout{display:flex;justify-content:space-between;align-items:center;gap:10px;font-size:13px;line-height:1.6;margin-top:14px}
.model-readout span{color:var(--muted);font-size:12px;white-space:nowrap}
.plot{width:100%;margin:8px 0}
.plot svg{display:block;width:100%;height:auto;overflow:visible;font-family:LabKorean,system-ui,sans-serif}
.plot text{fill:var(--muted);font-size:12px}.plot .axis-title{font-size:13px;fill:var(--ink)}
.plot .plot-bg{fill:var(--plot)}.plot .grid-line{stroke:var(--grid);stroke-width:1}.plot .axis{stroke:var(--muted);stroke-width:1.2}
.plot .trace{fill:none;stroke:var(--accent);stroke-width:2.4;stroke-linejoin:round}.plot .band-focus{fill:var(--accent);opacity:.13}
.plot .peak{stroke:var(--accent);stroke-width:3}.plot .reference{stroke:var(--muted);stroke-dasharray:4 4}
.instruction{font-size:13px;font-weight:700;margin:4px 0 12px}
.band-buttons{display:flex;flex-wrap:wrap;gap:7px}
.band-buttons button{background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:7px 10px;min-height:44px;color:var(--ink);font-size:12px;text-align:left;line-height:1.65}
.band-buttons button span{display:block;color:var(--muted);font-size:11px}
.band-buttons button[aria-pressed=true]{border-color:var(--accent);background:var(--soft)}
.insight{background:var(--soft);border-left:2px solid var(--accent);padding:12px 14px;margin-top:16px;border-radius:0 6px 6px 0}
.insight strong{font-size:13px}.insight p{font-size:13px;margin-top:6px;color:var(--muted);line-height:1.75}
.observation,.caption{font-size:12px;color:var(--muted);line-height:1.75;margin-top:14px}
.demo-panel>.caption{text-align:right;margin-top:12px}
.nmr-readout{margin:0;display:grid;gap:12px}
.nmr-readout div{border-bottom:1px solid var(--line);padding-bottom:10px;display:flex;align-items:center;justify-content:space-between;gap:12px}
.nmr-readout dt{font-size:12px;max-width:125px}.nmr-readout dd{margin:0;font-size:20px;font-weight:700;white-space:nowrap;font-variant-numeric:tabular-nums}
.nmr-readout dd small{font-size:12px;font-weight:400;color:var(--muted)}
.coverage-section{border-top:1px solid var(--line)}
.coverage-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}
.coverage-grid article{padding:18px 20px;border:1px solid var(--line);border-radius:9px;background:var(--surface)}
.coverage-grid h3{font-size:16px}.coverage-grid p{margin-top:8px;color:var(--muted);font-size:13px;line-height:1.75}
.chapter-details{margin-top:16px}.chapter-details summary{cursor:pointer;color:var(--accent);font-size:13px;width:fit-content}
.chapter-list{list-style:none;display:flex;flex-wrap:wrap;gap:7px;padding:0;margin:14px 0 0}
.chapter-list li{border:1px solid var(--line);border-radius:6px;font-size:12px;padding:4px 10px}
.practice-section{padding-top:28px}
.practice-content{padding:22px;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
.question-picker{display:flex;flex-wrap:wrap;gap:8px}
.question-card{margin-top:20px}
.lab-tag{display:block;font-size:11px;font-weight:700;letter-spacing:.025em;color:var(--muted);margin-bottom:5px}
.question-heading h3{font-size:19px}
.question-prompt{margin-top:14px;white-space:pre-line;line-height:1.85}
.question-figure{display:block;width:100%;max-height:300px;object-fit:contain;margin:18px auto;min-height:130px}
.question-figure.spectral{max-height:410px}
.question-answers{border:0;margin:0;padding:0;min-width:0}
.question-answers legend{font-size:12px;color:var(--muted);margin-bottom:10px}
.question-choices{display:grid;gap:8px}
.choice{display:flex;align-items:center;gap:12px;padding:10px 14px;border:1px solid var(--line);border-radius:7px;cursor:pointer;font-size:14px;line-height:1.7;min-height:48px}
.choice:has(input:checked){border-color:var(--accent);background:var(--soft)}
.choice:has(input:focus-visible){outline:3px solid var(--focus);outline-offset:3px}
.choice input{accent-color:var(--accent);width:18px;height:18px;flex-shrink:0;margin:0}
.choice .choice-number{font-size:16px;flex-shrink:0}
.choice img{display:block;width:100%;max-width:220px;height:108px;object-fit:contain}
.choice.correct{border-color:var(--right)}.choice.wrong{border-color:var(--wrong)}
.choice-result{margin-left:auto;white-space:nowrap;font-size:12px;font-weight:700}
.choice.correct .choice-result{color:var(--right)}.choice.wrong .choice-result{color:var(--wrong)}
.question-choices.with-figures{grid-template-columns:repeat(2,minmax(0,1fr))}
.with-figures .choice{flex-wrap:wrap;gap:8px}.with-figures .choice img{margin:auto}
.question-controls{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:20px}
.selection-note{font-size:12px;color:var(--muted)}
.question-feedback{margin-top:20px;border-top:1px solid var(--line);padding-top:18px}
.question-feedback h4{font-size:16px;margin:0 0 8px}.question-feedback p{font-size:14px;margin-top:10px}
.question-feedback .correction{padding:12px 14px;background:var(--soft);border-radius:7px}
.question-feedback a{font-size:13px;font-weight:700;display:inline-block;margin-top:12px}
.question-feedback .correct-label{color:var(--right)}.question-feedback .wrong-label{color:var(--wrong)}
.question-figure,.choice img{filter:invert(1) hue-rotate(180deg)}
html[data-theme=night] .question-figure,html[data-theme=night] .choice img{filter:none}
.sources-section{padding-top:28px;margin-top:12px;border-top:1px solid var(--line)}
.source-list{list-style:none;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 28px;padding:0;margin:0}
.source-list li{padding:16px 0;border-top:1px solid var(--line);min-width:0}
.source-kind{display:block;font-size:11px;color:var(--muted);margin-bottom:5px}
.source-list a{display:inline;font-size:14px;font-weight:700;line-height:1.7;overflow-wrap:anywhere;letter-spacing:0}
.source-list cite{font-style:normal}
.source-list p{font-size:12px;color:var(--muted);margin-top:5px;letter-spacing:0;word-break:normal}
.contact-section{display:flex;justify-content:space-between;align-items:center;gap:24px;padding:22px 24px;border-radius:10px;background:var(--soft);border:1px solid var(--line)}
.contact-section h2{font-size:17px}.contact-section p{font-size:13px;color:var(--muted);margin-top:5px}
.contact-section .button{flex-shrink:0}
.site-footer{padding:24px 0 32px;display:flex;justify-content:space-between;gap:16px;font-size:12px;color:var(--muted)}
.notice{padding:14px;border:1px solid var(--line);border-radius:8px;margin-top:16px}
@media(max-width:680px){
  .header-inner{padding:12px 18px;gap:12px}.brand{flex-direction:column;align-items:flex-start;gap:0;line-height:1.5}.brand strong{font-size:14px}.brand span{font-size:8px}
  .header-inner nav{gap:13px}.theme-toggle{padding:4px 9px}
  .section,.site-footer{width:calc(100% - 36px)}h1{font-size:24px}h2{font-size:19px}
  .hero{padding:30px 0 26px}.hero p{font-size:14px;line-height:1.9;margin-top:16px}
  .hero .button{min-height:40px;padding:7px 14px;margin-top:18px}
  .section-heading{gap:10px;margin-bottom:12px}.section-heading>span{font-size:11px}
  .section-intro{font-size:13px;margin-bottom:16px}.section-link{font-size:11px}
  .demo-section{padding-top:24px}
  .demo-tabs button{flex:1;justify-content:center;gap:7px;padding:11px 9px;min-width:0}.demo-tabs strong{font-size:14px}.demo-tabs span{font-size:11px}
  .demo-panel{padding:16px 12px}
  .lab-grid{grid-template-columns:1fr;gap:18px}.lab-notes{border-top:1px solid var(--line);padding-top:14px}
  .model-readout{font-size:12px;gap:8px}.model-readout span{font-size:11px}
  .segmented button{padding:7px 12px}.band-buttons{gap:6px}.band-buttons button{flex:1;min-width:80px}
  .instruction{margin:0 0 10px}.insight{margin-top:12px}
  .demo-panel>.caption{font-size:11px}
  .nmr-readout{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}
  .nmr-readout div{display:block;padding-bottom:8px}.nmr-readout dt{max-width:none;font-size:11px}
  .nmr-readout dd{font-size:19px;margin-top:3px}.nmr-readout dd small{font-size:11px}
  .coverage-section{padding:22px 0}.coverage-grid{grid-template-columns:1fr;gap:8px}
  .coverage-grid article{display:grid;grid-template-columns:106px 1fr;gap:10px;align-items:center;padding:13px 14px}
  .coverage-grid h3{font-size:14px}.coverage-grid p{margin:0;font-size:12px}
  .practice-section{padding-top:24px;padding-bottom:24px}.practice-content{padding:16px 12px}
  .question-heading h3{font-size:17px}.question-prompt{font-size:14px}
  .question-figure{max-height:260px;margin:15px auto}.question-figure.spectral{max-height:none}
  .choice{padding:9px 11px;gap:9px;font-size:13px}
  .question-choices.with-figures{grid-template-columns:1fr}.with-figures .choice{flex-wrap:nowrap}.with-figures .choice img{height:96px;max-width:180px}
  .question-controls .selection-note{flex-basis:100%}
  .sources-section{padding-top:24px;margin-top:0}.source-list{grid-template-columns:1fr;gap:0}.source-list li{padding:14px 0}
  .source-list a{font-size:13px}.source-list p{font-size:11px}
  .contact-section{padding:18px 16px;gap:14px}.contact-section h2{font-size:15px}.contact-section p{font-size:12px}
  .contact-section .button{padding:8px 12px}
  .site-footer{font-size:11px;padding:22px 0 28px}
}
@media(max-width:359px){.brand span{display:none}.header-inner nav{gap:10px}.model-readout{flex-direction:column;align-items:flex-start;gap:3px}.demo-tabs button{flex-direction:column;gap:1px}.coverage-grid article{grid-template-columns:92px 1fr}.contact-section{align-items:flex-start;flex-direction:column}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}