/* ============================================================
   Engineering Structures — modern design system
   ============================================================ */
:root{
  --navy:#0f2942;          /* deep structural steel */
  --navy-700:#173a5e;
  --navy-900:#0a1c2e;
  --amber:#f5a623;         /* hi-vis accent — backgrounds / on-dark only */
  --amber-600:#e08e0b;     /* button hover bg */
  --amber-ink:#a85d00;     /* accessible amber as TEXT on light (4.96:1) */
  --ink:#1b2733;
  --slate:#516072;
  --slate-300:#5f6e7e;     /* muted text, AA-compliant on white (5.23:1) */
  --line:#e4e9ef;
  --bg:#ffffff;
  --bg-soft:#f5f7fa;
  --bg-tint:#eef3f8;
  --radius:14px;
  --radius-lg:22px;
  --shadow-sm:0 1px 2px rgba(15,41,66,.06),0 2px 8px rgba(15,41,66,.05);
  --shadow:0 6px 24px rgba(15,41,66,.10);
  --shadow-lg:0 18px 50px rgba(15,41,66,.16);
  --container:1180px;
  --serif:'Fraunces',Georgia,serif;
  --sans:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;font-family:var(--sans);color:var(--ink);background:var(--bg);
  line-height:1.65;-webkit-font-smoothing:antialiased;font-size:17px;
}
img{max-width:100%;height:auto;display:block}
a{color:var(--navy-700);text-decoration:none;transition:color .15s}
a:hover{color:var(--amber-ink)}
.container{max-width:var(--container);margin:0 auto;padding:0 24px}
.container--narrow{max-width:760px}
h1,h2,h3,h4{font-family:var(--serif);color:var(--navy);line-height:1.18;font-weight:600;letter-spacing:-.01em}

/* ---------- buttons ---------- */
.btn{display:inline-block;padding:.85rem 1.5rem;border-radius:999px;font-weight:600;
  font-size:.97rem;cursor:pointer;border:2px solid transparent;transition:.18s;text-align:center}
.btn-primary{background:var(--amber);color:var(--navy-900);border-color:var(--amber)}
.btn-primary:hover{background:var(--amber-600);border-color:var(--amber-600);color:var(--navy-900);transform:translateY(-1px)}
.btn-ghost{background:transparent;color:#fff;border-color:rgba(255,255,255,.5)}
.btn-ghost:hover{background:#fff;color:var(--navy);border-color:#fff}

/* ---------- header / nav ---------- */
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);
  backdrop-filter:saturate(160%) blur(10px);border-bottom:1px solid var(--line)}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:70px}
.brand{display:flex;align-items:center;gap:.55rem;font-size:1.18rem;color:var(--navy)}
.brand:hover{color:var(--navy)}
.brand-mark{color:var(--amber);font-size:1rem}
.brand-text{font-family:var(--sans);font-weight:500;letter-spacing:-.02em}
.brand-text strong{font-weight:700}
.main-nav ul{display:flex;align-items:center;gap:1.55rem;list-style:none;margin:0;padding:0}
.main-nav a{color:var(--slate);font-weight:500;font-size:.94rem}
.main-nav a:hover{color:var(--navy)}
.nav-cta{background:var(--navy);color:#fff!important;padding:.5rem 1.1rem;border-radius:999px}
.nav-cta:hover{background:var(--amber);color:var(--navy-900)!important}
.nav-toggle{display:none;flex-direction:column;gap:5px;background:none;border:0;cursor:pointer;padding:8px}
.nav-toggle span{width:24px;height:2px;background:var(--navy);border-radius:2px;transition:.25s}
/* Topics dropdown */
.has-dropdown{position:relative}
.dropdown-toggle{display:inline-flex;align-items:center;gap:.3rem;cursor:pointer}
.dropdown-toggle .caret{font-size:.6em;opacity:.7;transition:transform .15s}
.has-dropdown:hover .caret,.has-dropdown:focus-within .caret{transform:rotate(180deg)}
.main-nav .dropdown{display:block;position:absolute;top:100%;left:50%;transform:translateX(-50%) translateY(8px);
  min-width:248px;background:#fff;border:1px solid var(--line);border-radius:14px;
  box-shadow:var(--shadow);padding:.45rem;list-style:none;margin:0;gap:0;
  opacity:0;visibility:hidden;transition:.16s;z-index:60}
.has-dropdown:hover .dropdown,.has-dropdown:focus-within .dropdown{opacity:1;visibility:visible;transform:translateX(-50%) translateY(6px)}
.dropdown:before{content:"";position:absolute;top:-8px;left:0;right:0;height:8px} /* hover bridge */
.dropdown li{margin:0}
.dropdown a{display:block;padding:.6rem .85rem;border-radius:9px;font-size:.9rem;color:var(--slate);white-space:nowrap}
.dropdown a:hover{background:var(--bg-soft);color:var(--navy)}

/* ---------- hero ---------- */
.hero{background:radial-gradient(1200px 500px at 80% -10%,rgba(245,166,35,.18),transparent 60%),
  linear-gradient(160deg,var(--navy) 0%,var(--navy-900) 100%);color:#fff;overflow:hidden;position:relative}
.hero:after{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(255,255,255,.05) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.05) 1px,transparent 1px);
  background-size:46px 46px;mask-image:radial-gradient(70% 70% at 70% 20%,#000,transparent);pointer-events:none}
.hero-inner{position:relative;display:grid;grid-template-columns:1.5fr 1fr;gap:48px;align-items:center;padding:84px 24px}
.eyebrow{text-transform:uppercase;letter-spacing:.18em;font-size:.78rem;font-weight:600;color:var(--amber);margin:0 0 1rem}
.hero h1{color:#fff;font-size:clamp(2.1rem,4.4vw,3.5rem);margin:0 0 1.1rem;font-weight:600}
.hero-lead{font-size:1.12rem;color:#cfe0f0;max-width:42ch;margin:0 0 1.8rem}
.hero-actions{display:flex;gap:.9rem;flex-wrap:wrap}
.hero-stats{display:grid;gap:1rem}
.hero-stats div{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.12);
  border-radius:var(--radius);padding:1.1rem 1.3rem;backdrop-filter:blur(4px)}
.hero-stats strong{display:block;font-family:var(--serif);font-size:2rem;color:var(--amber)}
.hero-stats span{font-size:.86rem;color:#cfe0f0}

/* ---------- sections ---------- */
section{padding:64px 0}
.section-title{font-size:clamp(1.5rem,2.6vw,2.05rem);margin:0 0 .3rem}
.section-sub{color:var(--slate);margin:.2rem 0 0;max-width:60ch}
.section-head{display:flex;justify-content:space-between;align-items:flex-end;gap:1rem;margin-bottom:2rem;flex-wrap:wrap}
.link-more{font-weight:600;white-space:nowrap}
.featured{background:var(--bg-soft)}
.featured .section-title{margin-bottom:2rem}
.cat-section:nth-of-type(even){background:var(--bg-soft)}

/* ---------- cards ---------- */
.card-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:26px}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--radius-lg);overflow:hidden;
  box-shadow:var(--shadow-sm);transition:.2s;display:flex;flex-direction:column}
.card:hover{box-shadow:var(--shadow-lg);transform:translateY(-3px);border-color:#d4dde7}
.card-media{display:block;height:180px;background-size:cover;background-position:center;background-color:var(--bg-tint)}
.card-media--plain{display:flex;align-items:center;justify-content:center;
  background:linear-gradient(135deg,var(--navy-700),var(--navy));color:rgba(255,255,255,.4);
  font-family:var(--serif);font-size:1.1rem;letter-spacing:.02em}
.card-body{padding:1.2rem 1.3rem 1.4rem;display:flex;flex-direction:column;flex:1}
.card-cat{font-size:.74rem;text-transform:uppercase;letter-spacing:.1em;font-weight:700;color:var(--amber-ink)}
.card h3{font-size:1.16rem;margin:.45rem 0 .55rem;line-height:1.3}
.card h3 a{color:var(--navy)}
.card h3 a:hover{color:var(--amber-ink)}
.card p{margin:0 0 1rem;color:var(--slate);font-size:.95rem;flex:1}
.card-meta{font-size:.82rem;color:var(--slate-300);font-weight:500}

/* ---------- page wrappers ---------- */
.page{padding:56px 0 72px}
.page-head{margin-bottom:2.4rem}
.page-head h1{font-size:clamp(2rem,4vw,2.9rem);margin:0 0 .5rem}
.page-head p{color:var(--slate);font-size:1.08rem;margin:0}
.crumbs{font-size:.85rem;color:var(--slate-300);margin-bottom:1rem}
.crumbs a{color:var(--slate)}
.page--center{display:flex;align-items:center;min-height:60vh}

/* ---------- article ---------- */
.article{padding:48px 0 0}
.article-cat{display:inline-block;font-size:.76rem;text-transform:uppercase;letter-spacing:.12em;
  font-weight:700;color:var(--amber-ink);margin-bottom:.6rem}
.article h1{font-size:clamp(1.9rem,4vw,2.85rem);margin:.2rem 0 .8rem;line-height:1.14}
.article-meta{color:var(--slate-300);font-size:.9rem;font-weight:500;margin-bottom:1.4rem}
.article-hero-img{height:min(460px,52vw);background-size:cover;background-position:center;
  background-color:var(--bg-tint);margin:1rem 0 2.6rem;border-radius:0}
.article-body{font-size:1.08rem;color:#28333f}
.article-body p{margin:0 0 1.35rem}
.article-body h2{font-size:1.6rem;margin:2.4rem 0 1rem}
.article-body h3{font-size:1.25rem;margin:1.9rem 0 .8rem}
.article-body h4{font-size:1.08rem;margin:1.6rem 0 .6rem;color:var(--navy-700)}
.article-body ul,.article-body ol{margin:0 0 1.35rem;padding-left:1.3rem}
.article-body li{margin:.4rem 0}
.article-body a{color:var(--navy-700);text-decoration:underline;text-decoration-color:rgba(23,58,94,.4);text-underline-offset:3px}
.article-body a:hover{color:var(--amber-ink);text-decoration-color:var(--amber-ink)}
.article-body img{border-radius:var(--radius);margin:1.6rem 0;box-shadow:var(--shadow-sm)}
.article-body blockquote{margin:1.6rem 0;padding:.6rem 1.4rem;border-left:4px solid var(--amber);
  background:var(--bg-soft);color:var(--navy-700);font-style:italic;border-radius:0 var(--radius) var(--radius) 0}
.article-body table{width:100%;border-collapse:collapse;margin:1.6rem 0;font-size:.95rem}
.article-body th,.article-body td{border:1px solid var(--line);padding:.6rem .8rem;text-align:left}
.article-body th{background:var(--bg-soft)}
.article-cta{margin:3rem 0 1rem;padding:2rem;background:var(--bg-tint);border-radius:var(--radius-lg);text-align:center}
.article-cta h3{margin:0 0 .4rem;font-size:1.35rem}
.article-cta p{color:var(--slate);margin:0 0 1.2rem}
.related{background:var(--bg-soft);margin-top:3rem}

/* ---------- forms ---------- */
.newsletter .nl-title{display:block;font-weight:600;color:var(--navy);margin-bottom:.5rem;font-size:.95rem}
.nl-row{display:flex;gap:.5rem}
.newsletter input[type=email]{flex:1;min-width:0;padding:.7rem .9rem;border:1px solid var(--line);
  border-radius:999px;font:inherit;font-size:.95rem;background:#fff}
.newsletter.inline,.newsletter.home{max-width:480px;margin:0 auto}
.newsletter button{padding:.7rem 1.3rem;border:0;border-radius:999px;background:var(--amber);
  color:var(--navy-900);font-weight:600;cursor:pointer;white-space:nowrap;font:inherit;font-size:.92rem}
.newsletter button:hover{background:var(--amber-600);color:var(--navy-900)}
.newsletter input:focus,.contact-form input:focus,.contact-form textarea:focus{outline:2px solid var(--amber);border-color:var(--amber)}
.contact-grid{display:grid;grid-template-columns:1.4fr 1fr;gap:48px;align-items:start}
.contact-form .field{margin-bottom:1.1rem}
.contact-form label{display:block;font-weight:600;font-size:.9rem;margin-bottom:.35rem;color:var(--navy)}
.contact-form input,.contact-form textarea{width:100%;padding:.75rem .9rem;border:1px solid var(--line);
  border-radius:10px;font:inherit;font-size:1rem;background:#fff}
.contact-form textarea{resize:vertical}
.contact-aside{background:var(--bg-soft);padding:1.6rem;border-radius:var(--radius-lg)}
.contact-aside h3{font-size:1rem;margin:1.2rem 0 .3rem}
.contact-aside h3:first-child{margin-top:0}
.contact-aside p{margin:0;color:var(--slate);font-size:.95rem}
.form-status{font-size:.9rem;margin:.7rem 0 0;min-height:1.2em}
.form-status.ok{color:#177245;font-weight:600}
.form-status.err{color:#b3261e;font-weight:600}
.form-status.sending{color:var(--slate)}

/* ---------- home CTA ---------- */
.home-cta{background:linear-gradient(160deg,var(--navy),var(--navy-900));color:#fff}
.home-cta-inner{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:center}
.home-cta h2{color:#fff;font-size:1.9rem;margin:0 0 .4rem}
.home-cta p{color:#cfe0f0;margin:0}
.home-cta .newsletter .nl-title{color:#fff}
.home-cta .newsletter input[type=email]{background:rgba(255,255,255,.95)}

/* ---------- footer ---------- */
.site-footer{background:var(--navy-900);color:#b9c8d8;padding:56px 0 28px;font-size:.94rem}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1.6fr;gap:40px}
.footer-brand .brand-text{color:#fff;font-size:1.2rem;font-family:var(--sans)}
.footer-brand p{margin:.9rem 0 0;color:#8aa0b6;max-width:34ch}
.footer-contact a{color:var(--amber)}
.footer-col h4{color:#fff;font-family:var(--sans);font-size:.95rem;margin:0 0 .9rem;letter-spacing:.02em}
.footer-col ul{list-style:none;margin:0;padding:0}
.footer-col li{margin:.5rem 0}
.footer-col a{color:#b9c8d8}
.footer-col a:hover{color:var(--amber)}
.footer-newsletter .newsletter .nl-title{color:#fff;font-size:.9rem}
.footer-newsletter input[type=email]{background:#fff}
.footer-base{display:flex;justify-content:space-between;border-top:1px solid rgba(255,255,255,.1);
  margin-top:40px;padding-top:22px;font-size:.85rem;color:#7d93a8}
.footer-base p{margin:0}

/* ---------- 404 ---------- */
.big-404{font-family:var(--serif);font-size:clamp(5rem,18vw,10rem);color:var(--amber-ink);
  line-height:1;margin:0;font-weight:700}

/* ---------- responsive ---------- */
@media(max-width:900px){
  .hero-inner{grid-template-columns:1fr;gap:34px;padding:60px 24px}
  .hero-stats{grid-template-columns:repeat(3,1fr)}
  .card-grid{grid-template-columns:repeat(2,1fr)}
  .contact-grid{grid-template-columns:1fr;gap:28px}
  .footer-grid{grid-template-columns:1fr 1fr;gap:30px}
  .home-cta-inner{grid-template-columns:1fr;gap:22px}
}
@media(max-width:640px){
  body{font-size:16px}
  .nav-toggle{display:flex}
  .main-nav{position:fixed;inset:70px 0 auto 0;background:#fff;border-bottom:1px solid var(--line);
    transform:translateY(-130%);transition:transform .28s ease;box-shadow:var(--shadow);max-height:calc(100vh - 70px);overflow:auto}
  body.nav-open .main-nav{transform:translateY(0)}
  .main-nav ul{flex-direction:column;align-items:stretch;gap:0;padding:8px 0}
  .main-nav li{border-bottom:1px solid var(--line)}
  .main-nav a{display:block;padding:.95rem 24px}
  .nav-cta{border-radius:0;background:none;color:var(--navy)!important}
  /* dropdown expands inline on mobile */
  .has-dropdown .dropdown{position:static;transform:none;opacity:1;visibility:visible;
    box-shadow:none;border:0;border-radius:0;padding:0;min-width:0;background:var(--bg-soft)}
  .has-dropdown .dropdown a{padding-left:42px;font-size:.92rem}
  .dropdown-toggle{display:block;pointer-events:none}
  .dropdown-toggle .caret{display:none}
  .dropdown:before{display:none}
  .card-grid{grid-template-columns:1fr}
  .hero-stats{grid-template-columns:repeat(3,1fr);gap:.6rem}
  .hero-stats strong{font-size:1.5rem}
  .section-head{flex-direction:column;align-items:flex-start}
  .footer-grid{grid-template-columns:1fr}
  .footer-base{flex-direction:column;gap:.4rem}
  .nl-row{flex-direction:column}
  .newsletter button{width:100%}
}