:root{--ink:#14233b;--muted:#63758a;--line:#dde6ee;--cyan:#19b9ae;--blue:#296be8;--canvas:#f7fafc;--bg:#f1f5f9}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.55 Inter,"Segoe UI",system-ui,sans-serif}button,input,textarea,select{font:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid #17bbb0;outline-offset:3px}a{color:#145bb4}p{margin:0 0 13px}h1,h2,h3{line-height:1.15;letter-spacing:-.035em}h1{font-size:clamp(30px,4vw,53px);margin:10px 0 15px}h2{font-size:22px}h3{font-size:17px}
.lab4-header{position:sticky;top:0;z-index:10;display:flex;justify-content:space-between;align-items:center;gap:16px;padding:13px clamp(16px,4vw,68px);background:#fffefdf5;border-bottom:1px solid var(--line);backdrop-filter:blur(12px)}.lab4-brand{font-weight:850;font-size:22px;color:#12233c;text-decoration:none;letter-spacing:-.7px}.lab4-brand span{color:#0f9a96}.lab4-links{display:flex;gap:15px;align-items:center;flex-wrap:wrap;font-size:13px;font-weight:700}.lab4-links a{text-decoration:none}.lab4-links a[aria-current=page]{color:#0d998f;border-bottom:2px solid #14b9ad}.badge{display:inline-block;background:#e8f8f3;border:1px solid #bce8de;border-radius:100px;padding:4px 10px;color:#166f66;font-weight:750;font-size:11px;letter-spacing:.03em}.lab4-page{max-width:1500px;margin:auto;padding:32px clamp(16px,3vw,52px) 70px}.intro{display:grid;grid-template-columns:1.25fr .75fr;gap:40px;align-items:center;min-height:200px;margin-bottom:28px}.intro p{color:#52647a;max-width:810px;font-size:15px}.scientific-note{background:#112f4e;color:#cce4f0;border-radius:20px;padding:22px}.scientific-note strong{display:block;color:#fff;margin-bottom:7px}.scientific-note p{font-size:12px;color:#c5d4e3;margin:0}.workbench{display:grid;grid-template-columns:320px minmax(0,1fr);gap:20px;align-items:start}.panel{background:white;border:1px solid var(--line);border-radius:18px;box-shadow:0 12px 35px #18314809;padding:22px}.controls .group{margin:22px 0}.controls h2{margin:0 0 10px}.controls label{display:block;font-size:12px;color:#435773;font-weight:750;margin:11px 0 5px}.controls textarea,.controls input:not([type=range]),.controls select{display:block;width:100%;border:1px solid #cddbe7;border-radius:10px;padding:11px 12px;background:white;color:var(--ink)}.controls textarea{resize:vertical;min-height:180px;font:12px/1.5 "IBM Plex Mono",monospace}.fieldrow{display:flex;gap:9px}.fieldrow>*{flex:1;min-width:0}.button{border:1px solid #aacee5;background:#eef6fb;border-radius:10px;color:#13578e;padding:11px 14px;font-weight:800;font-size:13px}.button.primary{background:#1268df;border-color:#1268df;color:#fff}.button:hover{filter:brightness(.95)}.button:disabled{opacity:.5;cursor:default}.button-group{display:flex;gap:9px;flex-wrap:wrap}.button-group>*{flex:1}.status{margin:13px 0;padding:10px 12px;border-radius:10px;background:#eef6fa;color:#295579;font-size:12px}.status[data-kind=error]{background:#fff1eb;color:#9f3f23}.status[data-kind=ok]{background:#e9f8ed;color:#116d49}.display{min-width:0;display:grid;gap:18px}.display-head{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;align-items:center}.display-head h2{margin:0}.display-head p{color:var(--muted);margin:3px 0 0;font-size:12px}.visual-tabs{display:flex;gap:5px;background:#ebf1f7;padding:4px;border-radius:10px}.visual-tabs button{border:0;border-radius:8px;padding:8px 13px;background:transparent;color:#48647c;font-weight:800}.visual-tabs button[aria-pressed=true]{background:white;color:#0d579f;box-shadow:0 3px 8px #173b5e15}.visual-wrap{position:relative;background:#f8fbff;border-radius:15px;overflow:hidden;border:1px solid #e0eaf1}.visual-wrap canvas{display:block;width:100%;height:auto;max-height:530px}.colorbar{background:linear-gradient(90deg,#232f62,#22719c,#35beb0,#c5de78,#fac158);height:11px;border-radius:9px;margin:13px 0 4px}.barlabels{display:flex;justify-content:space-between;font-size:11px;color:#597189}.control-sliders{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:17px}.control-sliders label{font-size:12px;font-weight:750;display:block}.control-sliders input{width:100%;accent-color:#1f9baf;margin-top:9px}.result-metrics{display:grid;grid-template-columns:repeat(7,minmax(0,1fr));gap:8px}.result-metric{background:#f4f8fc;padding:12px 8px;border-radius:12px;border:1px solid #e4edf5;min-width:0}.result-metric span{display:block;font-size:12px;font-weight:800;color:#4b6886}.result-metric strong{display:block;font:700 clamp(14px,1.7vw,18px) "IBM Plex Mono",monospace;overflow-wrap:anywhere;margin:7px 0 2px}.result-metric small{font-size:11px;color:#728497}.trace-grid{display:grid;grid-template-columns:1fr 1fr;gap:17px}.trace-grid canvas{width:100%;display:block}.footnote{color:#65788c;font-size:12px}.notice{border-left:3px solid #d49926;background:#fff9e9;border-radius:5px;padding:12px;color:#74531e;font-size:12px}.bottom-nav{margin:35px 0;color:#66809a;font-size:13px}.bottom-nav a{font-weight:750}.lab4-footer{border-top:1px solid var(--line);padding:21px 30px;text-align:center;color:#6c7b89;font-size:12px}
@media(max-width:1030px){.intro{grid-template-columns:1fr}.workbench{grid-template-columns:1fr}.controls{order:1}.display{order:2}.result-metrics{grid-template-columns:repeat(4,1fr)}}@media(max-width:660px){.lab4-header{position:static;display:block}.lab4-links{margin-top:9px}.panel{padding:15px}.control-sliders,.trace-grid{grid-template-columns:1fr}.result-metrics{grid-template-columns:repeat(2,1fr)}.fieldrow{flex-wrap:wrap}.intro{gap:12px}.lab4-page{padding-top:20px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important}}

/* 4.1 controls and material-curve */
.roi-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.roi-grid label{margin-top:4px}.roi-grid input{min-width:0}.roi-controls .button-group{margin-top:12px}.material-curve canvas{display:block;width:100%;height:auto;max-width:900px}.material-curve .button{margin-top:12px}.material-curve .display-head{margin-bottom:16px}
@media(max-width:390px){.roi-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}

.sim-link-banner{border:1px solid #78d7cd;padding:8px 12px;border-radius:9px;background:#e4f9f7;color:#117d77!important}.sim-promo a{display:inline-block;background:#daf7f3;border:1px solid #71cfc6;border-radius:10px;padding:11px 15px;text-decoration:none;font-weight:800;color:#116d69}