/* Helicon Consulting — weld seam case study.
   Tokens match the main site (assets/site.css); page-specific rules below. */
:root{
  --bg:#000;--panel:#0d150d;--panel2:#121c11;--border:#30432e;--line:#22311f;
  --text:#f5f7f2;--body:#d1dacc;--muted:#a3b79b;--mint:#bddfac;--green:#18300e;
  --ideal:#9aa7a6;--edge:#bddfac;--holes:#e9b96e;
  --paper:#eceee8;
  --max:1180px;--r:10px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:96px}
body{margin:0;background:var(--bg);color:var(--text);font:400 17px/1.64 system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;-webkit-font-smoothing:antialiased;-webkit-text-size-adjust:100%;text-size-adjust:100%}
img,svg{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;cursor:pointer}
:focus-visible{outline:3px solid #d6f5bd;outline-offset:3px}
::selection{background:#36622c;color:#fff}
.container{width:min(var(--max),calc(100% - 64px));margin-inline:auto}
.skip{position:absolute;left:12px;top:-90px;background:#fff;color:#000;padding:12px;z-index:999}
.skip:focus{top:8px}
h1,h2,h3{margin:0;color:var(--text);font-weight:680}
h2{font-size:clamp(28px,3.2vw,40px);line-height:1.18;letter-spacing:-.028em;margin-bottom:16px}
h3{font-size:20px;line-height:1.32;letter-spacing:-.015em;margin-bottom:8px}
p{margin:0 0 16px;color:var(--body)}
strong{color:var(--text)}
.num,.specs dd,.tip,.scale em{font-variant-numeric:tabular-nums}

/* ---------- Header (identical to main site) ---------- */
.site-header{position:sticky;top:0;z-index:80;border-bottom:1px solid #283827;background:#020402ee;backdrop-filter:blur(14px)}
.header-row{display:flex;align-items:center;justify-content:space-between;min-height:82px;gap:24px}
.brand{display:flex;gap:13px;align-items:center;flex-shrink:0}
.brand-logo{display:grid;place-items:center;width:38px;height:38px;border:1px solid #8eae7d;transform:rotate(45deg)}
.brand-logo b{transform:rotate(-45deg);font-size:20px;letter-spacing:-.06em}
.brand-words{font-size:14px;font-weight:800;line-height:1;letter-spacing:.17em}
.brand-words small{display:block;font-size:10px;font-weight:600;letter-spacing:.23em;color:var(--muted);margin-top:8px}
.nav{display:flex;align-items:center;gap:25px}
.nav a{font-size:14px;font-weight:650;color:#d7e2d2;white-space:nowrap}
.nav a:hover,.nav a.active{color:#fff}
.nav a.active{border-bottom:1px solid var(--mint);padding-bottom:5px}
.nav .nav-contact{padding:10px 17px;border:1px solid #738e68;border-radius:30px;color:#fff}
.mobile-toggle{display:none;background:none;color:#edf5e9;border:1px solid #536b4b;padding:8px 14px;border-radius:6px}

/* ---------- Buttons ---------- */
.btns{display:flex;flex-wrap:wrap;gap:12px;margin-top:30px}
.btn{display:inline-flex;align-items:center;justify-content:center;background:#d0eaba;color:#092009;font-weight:760;font-size:15px;border:1px solid #d0eaba;padding:14px 23px;border-radius:8px;transition:background .2s}
.btn:hover{background:#e3f5d9}
.btn-secondary{background:transparent;color:var(--text);border-color:#5e7d53}
.btn-secondary:hover{background:#152813}
.text-link{color:#d4edc7;font-weight:700;font-size:15px}
.text-link:hover{text-decoration:underline;text-underline-offset:4px}
.text-btn{background:none;border:0;padding:0;color:#d4edc7;font-weight:700;font-size:15px;text-decoration:underline;text-decoration-color:#5e7d53;text-underline-offset:4px}
.text-btn:hover{text-decoration-color:currentColor}
.text-btn.inline{font-size:inherit}

/* ---------- Hero ---------- */
.hero{padding:34px 0 88px;border-bottom:1px solid var(--line)}
.crumbs{display:flex;gap:10px;font-size:14px;color:var(--muted);margin-bottom:46px}
.crumbs a{color:#d4edc7}
.crumbs a:hover{text-decoration:underline;text-underline-offset:3px}
.hero-grid{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,1fr);gap:56px;align-items:center}
.kicker{font-size:15px;color:var(--muted);margin-bottom:20px}
.headline{font-size:clamp(40px,4.9vw,72px);line-height:1.02;letter-spacing:-.045em;margin-bottom:30px}
.hl-row{display:block}
.hl-word{font-weight:400;color:#c4d1bf}
.hl-num{font-weight:760;white-space:nowrap}
.hl-ideal{color:var(--ideal)}
.hl-weld{color:var(--edge)}
.lead{font-size:clamp(18px,1.7vw,20px);line-height:1.6;color:#dae5d4;max-width:36em}
.hero-figure{margin:0}
.hero-figure .zoom{border-radius:var(--r);overflow:hidden;border:1px solid var(--border);aspect-ratio:4/4.4}
.hero-figure img{width:100%;height:100%;object-fit:cover}
figcaption{font-size:14px;color:var(--muted);margin-top:12px}

/* ---------- Signature: the scale ---------- */
.scale{margin-top:76px;padding:34px 36px 26px;background:var(--panel);border:1px solid var(--border);border-radius:14px}
.scale-head{display:flex;justify-content:space-between;align-items:baseline;gap:20px;flex-wrap:wrap;margin-bottom:26px}
.scale-title{font-size:22px;letter-spacing:-.015em;margin:0}
.scale-note{font-size:14px;color:var(--muted);margin:0}
.scale-row{display:grid;grid-template-columns:260px 1fr;gap:24px;align-items:center;min-height:52px}
.scale-label{font-size:15px;color:var(--body)}
.scale-track{position:relative;height:30px;background:repeating-linear-gradient(90deg,var(--line) 0 1px,transparent 1px 10%);border-left:1px solid #3a5236}
.band{position:absolute;top:0;bottom:0;left:calc(var(--a)*10%);width:calc((var(--b) - var(--a))*10%);border-radius:4px;transform-origin:left center;animation:grow 1s cubic-bezier(.2,.7,.2,1) both}
.band em{position:absolute;left:calc(100% + 12px);top:50%;transform:translateY(-50%);font-style:normal;font-size:15px;font-weight:700;white-space:nowrap}
.band-ideal{background:var(--ideal)}.band-ideal em{color:var(--ideal)}
.band-edge{background:var(--edge);animation-delay:.25s}.band-edge em{color:var(--edge)}
.band-holes{background:var(--holes);animation-delay:.4s}.band-holes em{color:var(--holes)}
.band-edge em,.band-holes em{left:auto;right:calc(100% + 12px)}
@keyframes grow{from{transform:scaleX(0);opacity:.3}to{transform:scaleX(1);opacity:1}}
.scale-axis{min-height:28px}
.ticks{background:none;border-left:0;height:20px}
.ticks i{position:absolute;left:calc(var(--t)*10%);transform:translateX(-50%);font-style:normal;font-size:13px;color:var(--muted)}

/* ---------- Sections ---------- */
.section{padding:96px 0}
.section-tint{background:linear-gradient(180deg,#060b06,#081008);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.section-head{max-width:46em;margin-bottom:44px}
.section-head p{font-size:18px;line-height:1.62}
.fine{font-size:14px;color:var(--muted);margin-top:18px;max-width:60em}

.zoom{display:block;width:100%;padding:0;border:0;background:none;cursor:zoom-in}
.light{background:var(--paper)}
.split{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:56px;align-items:center}
.prose{max-width:34em}
.prose p{font-size:18px}
.plate-figure,.wide-figure{margin:0;border-radius:var(--r);overflow:hidden;background:var(--paper)}
.plate-figure figcaption,.wide-figure figcaption{margin:0;padding:12px 18px;background:#d9ddd3;color:#2a3527}
.plate-figure img{width:100%;height:auto}
.wide-figure{margin-top:48px}
.wide-figure img{width:100%;height:auto}

/* Steps (a real sequence, so numbered) */
.steps{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:22px;counter-reset:s}
.steps li{display:flex;flex-direction:column}
.steps .zoom{border-radius:8px;overflow:hidden;aspect-ratio:4/3;background:var(--paper);margin-bottom:18px;border:1px solid var(--border)}
.steps img{width:100%;height:100%;object-fit:cover}
.steps h3{display:flex;align-items:center;gap:10px;font-size:18px}
.step-n{display:grid;place-items:center;flex:none;width:26px;height:26px;border-radius:50%;border:1px solid #5e7d53;font-size:13px;font-weight:700;color:var(--mint)}
.steps p{font-size:15px;line-height:1.55;margin:0}

/* Models table */
.models{border:1px solid var(--border);border-radius:14px;overflow:hidden}
.m-row{display:grid;grid-template-columns:minmax(0,1.5fr) minmax(0,1.4fr) .8fr .8fr .9fr;gap:20px;align-items:center;padding:20px 26px;border-top:1px solid var(--line);background:var(--panel)}
.m-row:first-child{border-top:0}
.m-head{background:var(--panel2);padding-block:14px;font-size:14px;color:var(--muted);font-weight:600}
.m-row .num{text-align:right;font-size:17px;color:var(--text)}
.m-row [data-label="Stress concentration"]{font-weight:700}
.m-name{display:flex;gap:14px;align-items:flex-start}
.m-name strong{display:block;font-size:17px;line-height:1.3}
.m-name small{display:block;font-size:14px;color:var(--muted);margin-top:3px}
.dot{flex:none;width:12px;height:12px;border-radius:50%;margin-top:6px}
.dot-ideal{background:var(--ideal)}.dot-edge{background:var(--edge)}.dot-holes{background:var(--holes)}
.m-bc{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.m-bc .zoom{border-radius:6px;overflow:hidden;height:96px}
.m-bc img{width:100%;height:100%;object-fit:contain;padding:4px}

/* Chart */
.chart-card{background:var(--panel);border:1px solid var(--border);border-radius:14px;padding:26px 26px 20px}
.legend{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:14px}
.legend button{display:inline-flex;align-items:center;gap:9px;padding:8px 14px;border-radius:30px;border:1px solid var(--border);background:transparent;font-size:14px;color:var(--body)}
.legend button[aria-pressed="true"]{background:#16241a;border-color:#5e7d53;color:var(--text)}
.legend button[aria-pressed="false"]{opacity:.55}
.legend i{width:10px;height:10px;border-radius:50%}
.chart-wrap{position:relative}
#scf-chart{width:100%;height:auto;overflow:visible}
.grid{stroke:#1f2d1c;stroke-width:1}
.axis{stroke:#4a6344;stroke-width:1}
.tick{fill:#a3b79b;font-size:13px}
.axis-label{fill:#c4d1bf;font-size:14px}
.band-label{font-size:13px;font-weight:600}
.pt{cursor:pointer;transition:r .12s}
.pt:hover,.pt:focus{r:7}
.pt:focus{outline:none;stroke:#fff;stroke-width:2}
.tip{position:absolute;pointer-events:none;background:#020402;border:1px solid #5e7d53;border-radius:8px;padding:8px 12px;font-size:14px;line-height:1.4;color:var(--text);white-space:nowrap;opacity:0;transform:translate(-50%,-120%);transition:opacity .12s}
.tip.on{opacity:1}
.tip small{display:block;color:var(--muted)}
.chart-foot{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap;align-items:baseline;border-top:1px solid var(--line);margin-top:10px;padding-top:14px}
.chart-foot p{font-size:14px;color:var(--muted);margin:0}
.why{max-width:46em;margin-top:48px}
.why p{font-size:17px}

/* Small multiples */
.multiples{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:18px}
.mult{background:var(--panel);border:1px solid var(--border);border-radius:12px;padding:16px 14px 10px}
.mult h3{font-size:15px;font-weight:650;margin:0 4px 2px;display:flex;gap:8px;align-items:center}
.mult h3 .dot{margin-top:0;width:10px;height:10px}
.mult svg{width:100%;height:auto}
.mult .tick{font-size:11px}
.mult .ln-path{fill:none;stroke-width:2}
.mesh-legend{display:flex;gap:24px;flex-wrap:wrap;margin-top:16px;font-size:14px;color:var(--muted)}
.mesh-legend span{display:inline-flex;align-items:center;gap:8px}
.ln{display:inline-block;width:22px;height:0;border-top:2px solid}
.ln-25{border-color:#e8efe4}.ln-75{border-color:#a3b79b;border-top-style:dashed}.ln-120{border-color:#5f7759;border-top-style:dotted;border-top-width:3px}

/* Interpretation */
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:22px}
.col-card{background:var(--panel);border:1px solid var(--border);border-radius:14px;padding:28px 30px}
.col-card ul{margin:10px 0 0;padding-left:20px}
.col-card li{color:var(--body);margin-bottom:10px;padding-left:4px}
.col-card li::marker{color:var(--mint)}

/* Specs */
.specs{display:grid;grid-template-columns:1fr 1fr;gap:0 48px;margin:28px 0 0}
.specs div{display:grid;grid-template-columns:120px 1fr;gap:18px;padding:16px 0;border-top:1px solid var(--line)}
.specs dt{color:var(--muted);font-size:15px}
.specs dd{margin:0;color:var(--text);font-size:16px}

/* CTA */
.cta-section{padding-top:20px}
.cta{display:flex;justify-content:space-between;align-items:center;gap:40px;padding:44px 48px;border-radius:16px;background:linear-gradient(120deg,#12240d,#0b160a);border:1px solid #3c5a33}
.cta h2{font-size:clamp(26px,2.8vw,34px);max-width:18em}
.cta p{margin:0;max-width:40em}
.cta .btn{flex:none}
.back{display:inline-block;margin-top:34px}

/* Footer (main site) */
.footer{border-top:1px solid var(--line);padding:38px 0;margin-top:40px}
.footer-inner{display:flex;justify-content:space-between;gap:24px;flex-wrap:wrap;align-items:center}
.footer p{margin:0;font-size:14px;color:var(--muted)}
.footer strong{color:#f5f8f3}
.footer-links{display:flex;gap:20px;flex-wrap:wrap;font-size:14px}
.footer-links a:hover{color:#fff}

/* Lightbox */
.lightbox{border:0;padding:0;background:transparent;color:var(--text);max-width:min(1200px,94vw);width:100%}
.lightbox::backdrop{background:rgba(0,0,0,.86)}
.lb-inner{background:var(--panel);border:1px solid var(--border);border-radius:12px;overflow:hidden}
#lb-img{width:100%;max-height:76vh;object-fit:contain;background:var(--paper)}
.lb-bar{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:14px 18px;flex-wrap:wrap}
.lb-bar p{margin:0;font-size:15px}
.lb-ctrl{display:flex;gap:8px}
.lb-ctrl button{background:transparent;border:1px solid #5e7d53;border-radius:6px;padding:7px 14px;font-size:14px}
.lb-ctrl button:hover{background:#152813}

/* ---------- Responsive ---------- */
@media (max-width:1040px){
  .nav{gap:18px}
  .multiples{grid-template-columns:repeat(2,minmax(0,1fr))}
  .steps{grid-template-columns:repeat(2,minmax(0,1fr));row-gap:36px}
}
@media (max-width:920px){
  .mobile-toggle{display:block}
  .nav{display:none;position:absolute;left:0;right:0;top:82px;flex-direction:column;align-items:flex-start;gap:0;background:#020402;border-bottom:1px solid #283827;padding:8px 32px 20px}
  .nav.open{display:flex}
  .nav a{padding:12px 0;font-size:16px}
  .nav a.active{border:0;color:var(--mint)}
  .nav .nav-contact{margin-top:8px;padding:10px 18px}
  .hero-grid,.split{grid-template-columns:1fr;gap:40px}
  .hero-figure .zoom{aspect-ratio:16/10}
  .m-head{display:none}
  .m-row{grid-template-columns:1fr 1fr 1fr;gap:14px}
  .m-name{grid-column:1/-1}
  .m-bc{grid-column:1/-1}
  .m-bc .zoom{height:130px}
  .m-row .num{text-align:left;font-size:16px}
  .m-row .num::before{content:attr(data-label);display:block;font-size:13px;color:var(--muted);font-weight:400;margin-bottom:2px}
  .two-col,.specs{grid-template-columns:1fr}
  .cta{flex-direction:column;align-items:flex-start;padding:34px 28px}
}
@media (max-width:640px){
  .container{width:calc(100% - 32px)}
  .nav{padding-inline:16px}
  .hero{padding-bottom:60px}
  .crumbs{margin-bottom:30px}
  .section{padding:68px 0}
  .scale{padding:24px 18px 18px;margin-top:52px}
  .scale-row{grid-template-columns:1fr;gap:6px;min-height:0;margin-bottom:16px}
  .scale-axis .scale-label{display:none}
  .band em{font-size:14px}
  .steps{grid-template-columns:1fr}
  .multiples{grid-template-columns:1fr}
  .m-row{padding:18px}
  .chart-card{padding:18px 12px 14px}
  .specs div{grid-template-columns:1fr;gap:2px}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .band{animation:none}
  *{transition:none!important}
}