@font-face{font-family:Public Sans Variable;font-style:normal;font-display:swap;font-weight:100 900;src:url(/_astro/public-sans-vietnamese-wght-normal.CtlIRbEm.woff2)format("woff2-variations");unicode-range:U+102-103,U+110-111,U+128-129,U+168-169,U+1A0-1A1,U+1AF-1B0,U+300-301,U+303-304,U+308-309,U+323,U+329,U+1EA0-1EF9,U+20AB}@font-face{font-family:Public Sans Variable;font-style:normal;font-display:swap;font-weight:100 900;src:url(/_astro/public-sans-latin-ext-wght-normal.MQgHevqp.woff2)format("woff2-variations");unicode-range:U+100-2BA,U+2BD-2C5,U+2C7-2CC,U+2CE-2D7,U+2DD-2FF,U+304,U+308,U+329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}@font-face{font-family:Public Sans Variable;font-style:normal;font-display:swap;font-weight:100 900;src:url(/_astro/public-sans-latin-wght-normal.DdeTHZLK.woff2)format("woff2-variations");unicode-range:U+??,U+131,U+152-153,U+2BB-2BC,U+2C6,U+2DA,U+2DC,U+304,U+308,U+329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:500;src:url(/_astro/barlow-semi-condensed-vietnamese-500-normal.DGADhYWF.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-vietnamese-500-normal.hJ2t9k9e.woff)format("woff");unicode-range:U+102-103,U+110-111,U+128-129,U+168-169,U+1A0-1A1,U+1AF-1B0,U+300-301,U+303-304,U+308-309,U+323,U+329,U+1EA0-1EF9,U+20AB}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:500;src:url(/_astro/barlow-semi-condensed-latin-ext-500-normal.BXdp1BvY.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-ext-500-normal.rZeYuEMb.woff)format("woff");unicode-range:U+100-2BA,U+2BD-2C5,U+2C7-2CC,U+2CE-2D7,U+2DD-2FF,U+304,U+308,U+329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:500;src:url(/_astro/barlow-semi-condensed-latin-500-normal.G0uxJNrM.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-500-normal.CFOoVYFH.woff)format("woff");unicode-range:U+??,U+131,U+152-153,U+2BB-2BC,U+2C6,U+2DA,U+2DC,U+304,U+308,U+329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:600;src:url(/_astro/barlow-semi-condensed-vietnamese-600-normal.b1FQiZcx.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-vietnamese-600-normal.DzVrjA0Q.woff)format("woff");unicode-range:U+102-103,U+110-111,U+128-129,U+168-169,U+1A0-1A1,U+1AF-1B0,U+300-301,U+303-304,U+308-309,U+323,U+329,U+1EA0-1EF9,U+20AB}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:600;src:url(/_astro/barlow-semi-condensed-latin-ext-600-normal.BkQ9hN72.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-ext-600-normal.BuP8AaxH.woff)format("woff");unicode-range:U+100-2BA,U+2BD-2C5,U+2C7-2CC,U+2CE-2D7,U+2DD-2FF,U+304,U+308,U+329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:600;src:url(/_astro/barlow-semi-condensed-latin-600-normal.BkLiAYu4.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-600-normal.DyOfdMBA.woff)format("woff");unicode-range:U+??,U+131,U+152-153,U+2BB-2BC,U+2C6,U+2DA,U+2DC,U+304,U+308,U+329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:700;src:url(/_astro/barlow-semi-condensed-vietnamese-700-normal.Dm7RZTvf.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-vietnamese-700-normal.BvUTSFNY.woff)format("woff");unicode-range:U+102-103,U+110-111,U+128-129,U+168-169,U+1A0-1A1,U+1AF-1B0,U+300-301,U+303-304,U+308-309,U+323,U+329,U+1EA0-1EF9,U+20AB}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:700;src:url(/_astro/barlow-semi-condensed-latin-ext-700-normal.BhgEo64M.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-ext-700-normal.C0vCoZIV.woff)format("woff");unicode-range:U+100-2BA,U+2BD-2C5,U+2C7-2CC,U+2CE-2D7,U+2DD-2FF,U+304,U+308,U+329,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}@font-face{font-family:Barlow Semi Condensed;font-style:normal;font-display:swap;font-weight:700;src:url(/_astro/barlow-semi-condensed-latin-700-normal.BpqDG8I9.woff2)format("woff2"),url(/_astro/barlow-semi-condensed-latin-700-normal.BMyZXq_9.woff)format("woff");unicode-range:U+??,U+131,U+152-153,U+2BB-2BC,U+2C6,U+2DA,U+2DC,U+304,U+308,U+329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}:root{--bitumen:#1c2528;--road:#f2f4f3;--panel:#fff;--sign:#0b5d47;--sign-deep:#08463a;--sign-tint:#e3efe9;--amber:#f0b429;--amber-tint:#fdf3d8;--red:#b42318;--red-tint:#fbe7e5;--steel:#56656a;--rule:#d3dbda;--plate:#e4e9e8;--plate-edge:#b9c3c2;--head:"Barlow Semi Condensed", "Arial Narrow", sans-serif;--body:"Public Sans Variable", "Public Sans", system-ui, sans-serif;--step--1:.875rem;--step-0:1.0625rem;--step-1:1.25rem;--step-2:1.5625rem;--step-3:2rem;--step-4:2.75rem;--radius:6px;--wrap:72rem;color-scheme:light}*,:before,:after{box-sizing:border-box}html{-webkit-text-size-adjust:100%}body{background:var(--road);color:var(--bitumen);font-family:var(--body);font-size:var(--step-0);text-rendering:optimizelegibility;margin:0;line-height:1.6}img,svg{max-width:100%;height:auto}a{color:var(--sign);text-underline-offset:.18em;text-decoration-thickness:1px}a:hover{color:var(--sign-deep);text-decoration-thickness:2px}:focus-visible{outline:3px solid var(--amber);outline-offset:2px;border-radius:2px}h1,h2,h3{font-family:var(--head);letter-spacing:-.005em;text-wrap:balance;margin:0 0 .5em;font-weight:700;line-height:1.12}h1{font-size:clamp(2.1rem, 1.5rem + 2.6vw, var(--step-4))}h2{font-size:var(--step-3);margin-top:1.6em}h3{font-size:var(--step-2);margin-top:1.4em;font-weight:600}p{margin:0 0 1em}.wrap{max-width:var(--wrap);margin:0 auto;padding:0 1rem}@media (width>=48rem){.wrap{padding:0 2rem}}.visually-hidden:not(:focus){clip-path:inset(50%);white-space:nowrap;width:1px;height:1px;position:absolute;overflow:hidden}a.visually-hidden:focus{z-index:10;background:var(--panel);padding:.5rem 1rem;position:absolute;top:.5rem;left:.5rem}.site-header{background:var(--bitumen);color:#fff;border-bottom:4px solid var(--sign)}.site-header .wrap{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:1rem;min-height:4rem;display:flex}.logo{color:#fff;font-family:var(--head);letter-spacing:.01em;align-items:center;gap:.55rem;font-size:1.55rem;font-weight:700;text-decoration:none;display:inline-flex}.logo:hover{color:#fff}.logo svg{width:2rem;height:2rem}.logo b{color:var(--amber);font-weight:700}.nav-toggle{font:600 1rem var(--body);color:#fff;border-radius:var(--radius);cursor:pointer;background:0 0;border:1px solid #fff5;padding:.4rem .85rem}.site-nav{width:100%;padding-bottom:.75rem;display:none}.site-nav.open{display:block}.site-nav ul{gap:.15rem;margin:0;padding:0;list-style:none;display:grid}.site-nav a{color:#e9eeed;padding:.45rem .25rem;font-weight:500;text-decoration:none;display:block}.site-nav a:hover,.site-nav a[aria-current=page]{color:var(--amber)}@media (width>=62rem){.nav-toggle{display:none}.site-nav{width:auto;padding:0;display:block}.site-nav ul{gap:1.35rem;display:flex}.site-nav a{border-bottom:2px solid #0000;padding:.25rem 0;font-size:.97rem}.site-nav a[aria-current=page]{border-bottom-color:var(--amber)}}.page-head{max-width:46rem;padding:2.25rem 0 1.25rem}.page-head p{font-size:var(--step-1);color:var(--steel);margin:0}.crumbs{font-size:var(--step--1);color:var(--steel);margin-bottom:.75rem}.crumbs a{color:var(--steel)}.answer{background:var(--panel);border-left:5px solid var(--sign);border-radius:0 var(--radius) var(--radius) 0;max-width:46rem;margin:0 0 1.75rem;padding:1rem 1.25rem}.answer p:last-child{margin:0}.answer strong:first-child{font-family:var(--head);font-size:var(--step-1);margin-bottom:.2rem;display:block}.tool{align-items:start;gap:1.5rem;margin-bottom:3rem;display:grid}@media (width>=62rem){.tool{grid-template-columns:minmax(0,1fr) minmax(0,1.05fr);gap:2rem}.tool>.plate{position:sticky;top:1rem}}.form{background:var(--panel);border:1px solid var(--rule);border-radius:var(--radius);padding:1.25rem}@media (width>=48rem){.form{padding:1.5rem 1.75rem}}.form fieldset{border:0;min-width:0;margin:0 0 1.5rem;padding:0}.form fieldset:last-of-type{margin-bottom:1rem}.form legend{font-family:var(--head);font-weight:600;font-size:var(--step-1);margin-bottom:.6rem;padding:0}.form legend small{font-family:var(--body);font-weight:400;font-size:var(--step--1);color:var(--steel);display:block}.fields{gap:.9rem 1rem;display:grid}@media (width>=30rem){.fields{grid-template-columns:1fr 1fr}}.field{align-content:start;gap:.25rem;display:grid}.field>span{font-size:.95rem;font-weight:600;line-height:1.3}.field small{color:var(--steel);font-size:.8rem;line-height:1.35}.input{border-radius:var(--radius);background:#fff;border:1px solid #9eabaa;align-items:stretch;display:flex;overflow:hidden}.input:focus-within{border-color:var(--sign);box-shadow:0 0 0 3px var(--sign-tint)}.input input,.input select{min-width:0;font:500 1.125rem var(--body);font-variant-numeric:tabular-nums;color:var(--bitumen);background:0 0;border:0;flex:1;padding:.55rem .7rem}.input input:focus,.input select:focus{outline:none}.input .unit{background:var(--road);color:var(--steel);border-left:1px solid var(--rule);place-items:center;padding:0 .7rem;font-size:.9rem;display:grid}.choice{flex-wrap:wrap;gap:.5rem;display:flex}.choice label{border-radius:var(--radius);cursor:pointer;background:#fff;border:1px solid #9eabaa;align-items:center;gap:.4rem;padding:.4rem .75rem;font-size:.95rem;display:inline-flex}.choice label:has(input:checked){border-color:var(--sign);background:var(--sign-tint);font-weight:600}.choice input{accent-color:var(--sign)}.optional{border-top:1px dashed var(--rule);padding-top:1rem}.optional summary{cursor:pointer;color:var(--sign);font-weight:600}.optional[open] summary{margin-bottom:.8rem}.form-actions{flex-wrap:wrap;gap:.75rem;display:flex}.btn{font:600 .95rem var(--body);border-radius:var(--radius);cursor:pointer;border:1px solid var(--sign);color:var(--sign);background:#fff;padding:.55rem 1rem;text-decoration:none;display:inline-block}.btn:hover{background:var(--sign-tint)}.btn.primary{background:var(--sign);color:#fff}.btn.primary:hover{background:var(--sign-deep);color:#fff}.plate{background:linear-gradient(180deg, #edf1f0 0%, var(--plate) 100%);border:1px solid var(--plate-edge);border-radius:10px;padding:1.5rem 1.4rem 1.25rem;position:relative;box-shadow:inset 0 1px #fff,0 1px #c8d0cf}.plate:before,.plate:after{content:"";background:radial-gradient(circle at 35% 35%,#fff 0 20%,#a9b4b3 60%,#8b9796 100%);border-radius:50%;width:.6rem;height:.6rem;position:absolute;top:.7rem}.plate:before{left:.7rem}.plate:after{right:.7rem}@media (width>=48rem){.plate{padding:1.75rem 1.9rem 1.5rem}}.plate h2{font-size:var(--step-1);color:var(--steel);margin:0 0 .25rem;font-weight:600}.verdict{font-family:var(--head);margin:0 0 .35rem;font-size:clamp(1.75rem,1.4rem + 1.4vw,2.3rem);font-weight:700;line-height:1.1}.verdict.ok{color:var(--sign)}.verdict.close{color:#8a5a00}.verdict.over{color:var(--red)}.verdict-sub{color:var(--bitumen);margin:0 0 1.25rem}.big{font-family:var(--head);font-variant-numeric:tabular-nums;letter-spacing:-.01em;margin:.2rem 0 .4rem;font-size:clamp(3rem,2.2rem + 3vw,4.25rem);font-weight:700;line-height:1}.big small{color:var(--steel);margin-left:.15em;font-size:.45em;font-weight:600}.gauges{gap:1rem;margin:0;padding:0;list-style:none;display:grid}.gauge-top{justify-content:space-between;align-items:baseline;gap:.75rem;font-size:.93rem;display:flex}.gauge-top .lbl{font-weight:600}.gauge-top .val{font-variant-numeric:tabular-nums;white-space:nowrap;color:var(--steel)}.bar{border:1px solid var(--plate-edge);background:#fff;border-radius:3px;height:.8rem;margin:.35rem 0 .25rem;position:relative;overflow:hidden}.bar i{background:var(--sign);transition:width .25s;position:absolute;inset:0 auto 0 0}.bar.close i{background:var(--amber)}.bar.over i{background:var(--red)}.bar b{background:var(--bitumen);width:2px;position:absolute;top:-1px;bottom:-1px}.gauge-note{font-variant-numeric:tabular-nums;font-size:.85rem}.gauge-note.over{color:var(--red);font-weight:600}.gauge-note.close{color:#8a5a00;font-weight:600}@media (prefers-reduced-motion:reduce){.bar i{transition:none}}.readout{border-top:1px solid var(--plate-edge);gap:.35rem;margin:1.25rem 0 0;padding:.9rem 0 0;list-style:none;display:grid}.readout li{justify-content:space-between;gap:1rem;font-size:.95rem;display:flex}.readout .n{font-variant-numeric:tabular-nums;white-space:nowrap;font-weight:600}.rules{gap:.9rem;margin:0;padding:0;list-style:none;display:grid}.rules li{border:1px solid var(--plate-edge);border-radius:var(--radius);background:#fffa;padding:.75rem .9rem}.rules h3{margin:0 0 .2rem;font-size:1.15rem}.rules .topic{color:var(--steel);font-size:.8rem;font-weight:600}.rules p{margin:0;font-size:.93rem}.err{background:var(--red-tint);border-left:4px solid var(--red);border-radius:0 var(--radius) var(--radius) 0;margin:0;padding:.7rem .9rem}.plate-foot{color:var(--steel);margin:1.1rem 0 0;font-size:.82rem}.prose{max-width:44rem}.prose h2:first-child{margin-top:0}.prose ul,.prose ol{padding-left:1.25rem}.prose li{margin-bottom:.35em}.prose table{border-collapse:collapse;font-variant-numeric:tabular-nums;background:var(--panel);width:100%;margin:0 0 1.5rem;font-size:.95rem}.prose th,.prose td{text-align:left;border-bottom:1px solid var(--rule);vertical-align:top;padding:.5rem .65rem}.prose th{background:var(--sign-tint);font-weight:600}.table-scroll{margin:0 0 1.5rem;overflow-x:auto}.table-scroll table{min-width:30rem;margin:0}.prose code,.formula{font-family:var(--head);font-size:1.05em;font-weight:600}.formula{background:var(--panel);border:1px solid var(--rule);border-radius:var(--radius);margin:0 0 1rem;padding:.7rem .9rem;font-size:1.15rem;display:block}.prose blockquote{border-left:4px solid var(--amber);background:var(--amber-tint);margin:0 0 1em;padding:.6rem 1rem}.prose img{border-radius:var(--radius);border:1px solid var(--rule);display:block}.faq dt{margin-top:1rem;font-weight:700}.faq dd{margin:.25rem 0 0}.sources{font-size:.93rem}.sources li{margin-bottom:.5em}.checked{color:var(--steel);font-size:.9rem}.caution{background:var(--amber-tint);border-radius:var(--radius);border:1px solid #ecd28a;max-width:44rem;margin:2rem 0;padding:.85rem 1rem;font-size:.93rem}.caution p{margin:0}.tool-list{border-top:1px solid var(--rule);gap:0;margin:0;padding:0;list-style:none;display:grid}.tool-list li{border-bottom:1px solid var(--rule);gap:.15rem;padding:.9rem 0;display:grid}@media (width>=48rem){.tool-list li{grid-template-columns:19rem 1fr;align-items:baseline;gap:1.5rem}}.tool-list a{font-family:var(--head);font-size:1.3rem;font-weight:600;line-height:1.2}.tool-list p{color:var(--steel);margin:0}.related{margin:3rem 0 0}.hero{align-items:center;gap:2rem;padding:2.5rem 0;display:grid}@media (width>=62rem){.hero{grid-template-columns:1fr 1fr;gap:3rem;padding:3.5rem 0 3rem}}.hero h1{font-size:clamp(2.4rem,1.6rem + 3.4vw,3.6rem);line-height:1.04}.hero .lede{font-size:var(--step-1);color:var(--steel);max-width:34rem}.hero-actions{flex-wrap:wrap;gap:.75rem;margin-top:1.5rem;display:flex}.demo .fields{grid-template-columns:1fr 1fr}.demo .field>span{font-size:.85rem}.demo .input input{padding:.45rem .55rem;font-size:1rem}.demo .input .unit{padding:0 .5rem;font-size:.8rem}.demo-out{border-top:1px solid var(--plate-edge);margin-top:1rem;padding-top:1rem}.demo-out p{margin:0}.band{padding:2.5rem 0}.band h2{margin-top:0}.terms{border-top:1px solid var(--rule);gap:0;margin:0;display:grid}.terms div{border-bottom:1px solid var(--rule);gap:.15rem;padding:.75rem 0;display:grid}@media (width>=48rem){.terms div{grid-template-columns:5rem 15rem 1fr;align-items:baseline;gap:1.25rem}}.terms dt{font-family:var(--head);color:var(--sign);font-size:1.4rem;font-weight:700}.terms .full{font-weight:600}.terms dd{color:var(--bitumen);margin:0}.guide-list{gap:1.5rem;margin:0;padding:0;list-style:none;display:grid}@media (width>=48rem){.guide-list{grid-template-columns:1fr 1fr}}.guide-list a.card{color:inherit;gap:.6rem;text-decoration:none;display:grid}.guide-list img{border-radius:var(--radius);border:1px solid var(--rule);aspect-ratio:3/2;object-fit:cover;width:100%}.guide-list h3{color:var(--sign);margin:0;font-size:1.35rem}.guide-list a.card:hover h3{text-decoration:underline}.guide-list p{color:var(--steel);margin:0;font-size:.95rem}.article-head{max-width:46rem;padding:2.25rem 0 1.25rem}.byline{color:var(--steel);font-size:.93rem}.hero-img{max-width:46rem;margin:0 0 2rem}.hero-img img{border-radius:var(--radius);border:1px solid var(--rule);width:100%;display:block}.cta{background:var(--sign);color:#fff;border-radius:var(--radius);max-width:44rem;margin:2rem 0;padding:1.1rem 1.25rem}.cta p{margin:0 0 .6rem}.cta a{color:#fff;font-weight:700}.site-footer{background:var(--bitumen);color:#cfd8d7;margin-top:4rem;padding:2.5rem 0 2rem;font-size:.93rem}.site-footer a{color:#fff}.foot-grid{gap:1.5rem;display:grid}@media (width>=48rem){.foot-grid{grid-template-columns:1.3fr 1fr 1fr}}.site-footer h2{color:#fff;margin:0 0 .6rem;font-size:1.1rem}.site-footer ul{gap:.35rem;margin:0;padding:0;list-style:none;display:grid}.site-footer .fine{border-top:1px solid #fff2;margin-top:2rem;padding-top:1rem;font-size:.85rem}.peek{z-index:5;background:var(--bitumen);color:#fff;border-radius:var(--radius);border-left:6px solid var(--sign);justify-content:space-between;gap:.75rem;padding:.7rem 1rem;font-weight:600;text-decoration:none;display:flex;position:fixed;bottom:.75rem;left:.75rem;right:.75rem;box-shadow:0 6px 20px #1c252840}.peek:hover{color:#fff}.peek.close{border-left-color:var(--amber)}.peek.over{border-left-color:var(--red)}.peek span:last-child{opacity:.8;white-space:nowrap;font-weight:400}@media (width>=62rem){.peek{display:none!important}}.toc{background:var(--panel);border:1px solid var(--rule);border-radius:var(--radius);margin:0 0 1.75rem;padding:.85rem 1.1rem;font-size:.95rem}.toc p{margin:0 0 .3rem}.toc ul{margin:0}.page-head+.prose .guide-list,.prose:has(.guide-list){max-width:none}