.skip-link{position:absolute;left:-9999px;top:0;background:#102a43;color:#fff;padding:.7rem 1rem;z-index:100}.skip-link:focus{left:1rem;top:1rem}.nav-toggle{display:none;border:1px solid #dce3ea;background:#fff;color:#102a43;border-radius:8px;padding:.55rem .8rem;font:inherit;font-weight:700}.card-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1.25rem}.section-muted{background:#f7f9fc}.visual-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1.5rem}.visual-card{min-height:100%}.thermal-demo{display:flex;align-items:stretch;height:90px;margin:1.2rem 0}.hot-block,.cold-block{display:flex;align-items:center;justify-content:center;min-width:90px;color:#fff;font-weight:800}.hot-block{background:#dc4c3f;border-radius:12px 0 0 12px}.cold-block{background:#2f80ed;border-radius:0 12px 12px 0}.layer-block{background:#f59e0b;min-width:22px;transition:width .15s ease}.visual-result{font-size:1.15rem}.temperature-column{height:180px;width:64px;border:1px solid #9fb3c8;border-radius:10px;display:flex;align-items:flex-end;overflow:hidden;background:#f2f6fa;margin:1rem 0}.temperature-fill{width:100%;background:linear-gradient(0deg,#2f80ed,#f59e0b,#dc4c3f);transition:height .15s ease}.bar-track{height:18px;border-radius:99px;background:#e8eef3;overflow:hidden;flex:1}.bar-fill{height:100%;background:linear-gradient(90deg,#f59e0b,#dc4c3f);width:20%;transition:width .15s ease}.conductivity-row{display:grid;grid-template-columns:150px 1fr 70px;gap:.8rem;align-items:center;margin:.8rem 0}.quiz-actions{margin-top:1rem}.quiz-option{width:100%;text-align:left;background:#fff;color:#18212b;font:inherit}.quiz-option:disabled{cursor:default;opacity:.8}.nav-toggle+.main-nav{display:flex}@media(max-width:900px){.card-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.visual-grid{grid-template-columns:1fr}.nav-toggle{display:block}.header-inner{flex-direction:row!important;align-items:center!important}.main-nav{display:none!important;position:absolute;top:74px;left:16px;right:16px;background:#fff;border:1px solid #dce3ea;border-radius:12px;padding:1rem;box-shadow:0 10px 30px rgba(16,42,67,.12);flex-direction:column;align-items:flex-start!important}.main-nav.is-open{display:flex!important}}@media(max-width:640px){.card-grid{grid-template-columns:1fr}.conductivity-row{grid-template-columns:110px 1fr 55px;font-size:.86rem}.hot-block,.cold-block{min-width:70px;font-size:.85rem}}