/* HomeBuild Atlas — engineering blueprint palette */
:root{
  --navy:#102A43; --navy-dark:#0B1F33; --blue:#2563EB; --amber:#E99A22;
  --bg:#F7F5F0; --card:#FFFFFF; --text:#243B53; --muted:#627D98;
  --line:#DCE3EB; --success:#16803A; --danger:#B42318;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Georgia,'Times New Roman',serif;color:var(--text);background:var(--bg);line-height:1.65;font-size:17px}
h1,h2,h3,h4,.brand-name,.site-nav,.btn,.kicker,.card-cat,.byline,th,label,.result-label,.breadcrumbs,.tool-cta,.footer-grid h3{font-family:'Segoe UI',system-ui,-apple-system,Helvetica,Arial,sans-serif}
h1{font-size:2rem;line-height:1.2;color:var(--navy);margin:.3em 0}
h2{font-size:1.45rem;color:var(--navy);margin:1.6em 0 .5em}
h3{font-size:1.15rem;color:var(--navy);margin:1.2em 0 .4em}
p{margin:.7em 0}
a{color:var(--blue)}
img,svg{max-width:100%}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px}

/* header */
.site-header{background:var(--navy);position:sticky;top:0;z-index:50;box-shadow:0 1px 4px rgba(11,31,51,.3)}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:10px 20px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none}
.brand-name{color:#F7F5F0;font-weight:700;font-size:1.15rem;letter-spacing:.02em}
.brand-name em{font-style:normal;color:var(--amber)}
.site-nav{display:flex;gap:22px;align-items:center}
.site-nav a{color:#D9E2EC;text-decoration:none;font-size:.95rem;font-weight:600}
.site-nav a:hover{color:#fff}
.site-nav .nav-cta{background:var(--amber);color:var(--navy-dark);padding:7px 16px;border-radius:6px}
.nav-toggle{display:none;background:none;border:0;color:#fff;font-size:1.5rem;cursor:pointer}
@media(max-width:840px){
  .nav-toggle{display:block}
  .site-nav{display:none;position:absolute;top:56px;left:0;right:0;background:var(--navy-dark);flex-direction:column;padding:16px;gap:14px}
  .site-nav.open{display:flex}
}

/* hero */
.hero{background:linear-gradient(160deg,var(--navy) 0%,#16395C 100%);color:#D9E2EC;padding:64px 0 72px}
.hero h1{color:#fff;font-size:2.5rem;max-width:720px}
.hero p{max-width:640px;font-size:1.1rem}
.hero .btn{margin-top:14px}
@media(max-width:640px){.hero h1{font-size:1.9rem}}

/* buttons */
.btn{display:inline-block;background:var(--amber);color:var(--navy-dark);font-weight:700;padding:12px 24px;border-radius:8px;text-decoration:none;border:0;font-size:1rem;cursor:pointer}
.btn:hover{filter:brightness(1.06)}
.btn-secondary{background:transparent;color:#fff;border:2px solid #486581}
.btn-blue{background:var(--blue);color:#fff}

/* sections & cards */
.section{padding:48px 0}
.section-alt{background:#EFEBE2}
.kicker{color:var(--amber);font-weight:700;text-transform:uppercase;letter-spacing:.08em;font-size:.8rem;margin:0}
.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:18px;margin:20px 0}
.article-card,.tool-card{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:20px;text-decoration:none;display:flex;flex-direction:column;gap:8px;transition:box-shadow .15s,transform .15s}
.article-card:hover,.tool-card:hover{box-shadow:0 6px 18px rgba(16,42,67,.12);transform:translateY(-2px)}
.card-cat{color:var(--amber);font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em}
.card-title{color:var(--navy);font-weight:700;font-size:1.1rem;font-family:'Segoe UI',system-ui,sans-serif}
.card-summary{color:var(--text);font-size:.92rem}
.card-meta{color:var(--muted);font-size:.82rem;margin-top:auto}
.cat-heading{border-bottom:2px solid var(--amber);padding-bottom:6px;margin-top:2.2em}
.tool-card .tool-icon{font-size:1.6rem}

/* breadcrumbs */
.breadcrumbs{background:#EFEBE2;border-bottom:1px solid var(--line);font-size:.85rem;padding:8px 0;color:var(--muted)}
.breadcrumbs a{color:var(--muted);text-decoration:none}
.breadcrumbs a:hover{color:var(--blue)}
.breadcrumbs .sep{color:#B0BDCB;margin:0 2px}

/* article */
.article-page{max-width:780px;padding-top:28px;padding-bottom:56px}
.article-header .summary{font-size:1.12rem;color:var(--muted)}
.byline{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:10px 0;margin:18px 0;font-size:.88rem}
.byline p{margin:2px 0}
.byline-names{font-weight:600}
.byline-dates{color:var(--muted)}
.answer-box{background:#EAF1FE;border-left:4px solid var(--blue);padding:16px 18px;border-radius:0 8px 8px 0;margin:20px 0}
.answer-box strong{color:var(--navy)}
.tool-cta{background:var(--navy);color:#D9E2EC;padding:18px 20px;border-radius:10px;margin:26px 0;display:flex;flex-wrap:wrap;align-items:center;gap:14px;justify-content:space-between}
.tool-cta p{margin:0;color:#D9E2EC}
.tool-cta strong{color:#fff}
.warn-box{background:#FDF0E7;border-left:4px solid var(--danger);padding:14px 18px;border-radius:0 8px 8px 0;margin:20px 0;font-size:.95rem}
.pro-tip{background:#EDF7EF;border-left:4px solid var(--success);padding:14px 18px;border-radius:0 8px 8px 0;margin:20px 0;font-size:.95rem}

/* tables */
table{border-collapse:collapse;width:100%;margin:18px 0;background:var(--card);font-size:.93rem}
th{background:var(--navy);color:#fff;text-align:left;padding:9px 12px;font-size:.85rem}
td{border:1px solid var(--line);padding:8px 12px}
tbody tr:nth-child(even){background:#F4F6F9}
.table-scroll{overflow-x:auto}

/* formulas */
.formula{background:var(--navy-dark);color:#9FB3C8;font-family:'Consolas','Courier New',monospace;padding:14px 18px;border-radius:8px;margin:16px 0;overflow-x:auto;font-size:.95rem}
.formula strong{color:var(--amber);font-weight:400}

/* diagrams */
.diagram{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:18px;margin:22px 0;text-align:center}
.diagram figcaption{font-size:.85rem;color:var(--muted);margin-top:8px;font-family:'Segoe UI',system-ui,sans-serif}

/* FAQ */
.faq-section{margin-top:40px}
.faq-item{background:var(--card);border:1px solid var(--line);border-radius:8px;margin:10px 0;padding:0 18px}
.faq-item summary{font-weight:600;color:var(--navy);cursor:pointer;padding:14px 0;font-family:'Segoe UI',system-ui,sans-serif}
.faq-item p{padding-bottom:14px;margin:0}

/* related */
.related-section{margin-top:40px}
.related-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px}
.related-card{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:14px 16px;text-decoration:none;color:var(--navy);font-weight:600;display:flex;justify-content:space-between;gap:8px;font-family:'Segoe UI',system-ui,sans-serif;font-size:.92rem}
.related-card:hover{border-color:var(--blue)}
.related-card .arrow{color:var(--amber)}

/* calculator */
.calc-layout{display:grid;grid-template-columns:1fr 1fr;gap:26px;margin:26px 0}
@media(max-width:800px){.calc-layout{grid-template-columns:1fr}}
.calc-panel,.result-panel{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:24px}
.calc-panel h2,.result-panel h2{margin-top:0;font-size:1.2rem}
.field{margin-bottom:14px}
.field label{display:block;font-weight:600;font-size:.88rem;color:var(--navy);margin-bottom:4px}
.field input,.field select{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:7px;font-size:1rem;background:#FBFAF7;color:var(--text)}
.field input:focus,.field select:focus{outline:2px solid var(--blue);border-color:var(--blue)}
.field-row{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.result-panel{border-top:4px solid var(--amber)}
.result-big{font-size:2.2rem;font-weight:800;color:var(--navy);font-family:'Segoe UI',system-ui,sans-serif;margin:4px 0}
.result-big small{font-size:1rem;color:var(--muted);font-weight:600}
.result-label{color:var(--muted);font-size:.85rem;text-transform:uppercase;letter-spacing:.05em;margin:14px 0 0}
.result-row{display:flex;justify-content:space-between;border-bottom:1px dashed var(--line);padding:7px 0;font-size:.95rem}
.result-row strong{color:var(--navy)}
.calc-note{font-size:.85rem;color:var(--muted);margin-top:14px}
.tool-content{max-width:780px}

/* hero features */
.feature-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:18px;margin:24px 0}
.feature{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:18px}
.feature h3{margin-top:0}
.steps{counter-reset:step;display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:16px;margin:24px 0;padding:0;list-style:none}
.steps li{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:18px;counter-increment:step}
.steps li::before{content:counter(step);display:inline-flex;width:30px;height:30px;border-radius:50%;background:var(--amber);color:var(--navy-dark);font-weight:800;align-items:center;justify-content:center;margin-bottom:8px;font-family:'Segoe UI',system-ui,sans-serif}

/* footer */
.site-footer{background:var(--navy-dark);color:#9FB3C8;margin-top:56px;font-size:.9rem}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:28px;padding:44px 20px 24px}
@media(max-width:800px){.footer-grid{grid-template-columns:1fr 1fr}}
@media(max-width:500px){.footer-grid{grid-template-columns:1fr}}
.footer-grid h3{color:#fff;font-size:.95rem;margin:0 0 10px}
.footer-grid a{display:block;color:#9FB3C8;text-decoration:none;padding:3px 0}
.footer-grid a:hover{color:#fff}
.brand-footer .brand-name{font-size:1.05rem}
.footer-tag{font-size:.85rem;margin-top:10px}
.footer-legal{border-top:1px solid #243B53;padding-top:16px;padding-bottom:24px;font-size:.78rem;color:#627D98}

/* misc */
.center{text-align:center}
.muted{color:var(--muted)}
.legal-page{max-width:780px;padding-top:28px;padding-bottom:48px}
.author-box{display:flex;gap:18px;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:22px;margin:24px 0;align-items:flex-start}
.author-avatar{width:72px;height:72px;border-radius:50%;background:var(--navy);color:var(--amber);display:flex;align-items:center;justify-content:center;font-size:1.6rem;font-weight:800;font-family:'Segoe UI',system-ui,sans-serif;flex-shrink:0}
.placeholder-note{background:#FFF8E7;border:1px dashed var(--amber);padding:10px 14px;border-radius:8px;font-size:.85rem;color:#7A5B12}