:root{
    --paper:#ffffff;
    --ink:#111111;
    --accent:#FF4400;
    --grey:#6B6B6B;
    --hairline:#1A1A1A;
    --hairline-soft:#D9D9D9;
    --display: 'Space Grotesk', sans-serif;
    --body: 'IBM Plex Sans', sans-serif;
    --mono: 'IBM Plex Mono', monospace;
    --max-w: 1180px;
    --side-pad: clamp(24px, 6vw, 80px);
  }

  *{ box-sizing:border-box; }
  html{ scroll-behavior:smooth; }

  body{
    margin:0;
    background:var(--paper);
    color:var(--ink);
    font-family:var(--body);
    -webkit-font-smoothing:antialiased;
  }

  @media (prefers-reduced-motion: reduce){
    html{ scroll-behavior:auto; }
    *{ animation:none !important; transition:none !important; }
  }

  a{ color:inherit; }

  /* ---------- shared layout helpers ---------- */
  .wrap{
    max-width:var(--max-w);
    margin:0 auto;
    padding-left:var(--side-pad);
    padding-right:var(--side-pad);
  }

  .eyebrow{
    font-family:var(--mono);
    font-size:12px;
    letter-spacing:0.14em;
    text-transform:uppercase;
    color:var(--grey);
    display:flex;
    align-items:center;
    gap:10px;
  }
  .eyebrow .doc-no{ color:var(--accent); }
  .eyebrow::after{
    content:"";
    flex:1;
    height:1px;
    background:var(--hairline-soft);
  }

  /* ---------- header / nav ---------- */
  header{
    position:sticky;
    top:0;
    z-index:50;
    background:rgba(255,255,255,0.92);
    backdrop-filter:blur(6px);
    border-bottom:1px solid var(--hairline-soft);
  }
  .nav{
    display:flex;
    align-items:center;
    justify-content:space-between;
    height:64px;
  }
  .nav-mark{
    font-family:var(--display);
    font-weight:600;
    font-size:18px;
    letter-spacing:-0.01em;
    text-decoration:none;
    display:flex;
    align-items:center;
    gap:8px;
  }
  .nav-mark .dot{
    width:8px; height:8px;
    background:var(--accent);
    display:inline-block;
  }
  .nav-links{
    display:flex;
    gap:28px;
    font-family:var(--mono);
    font-size:12px;
    letter-spacing:0.08em;
    text-transform:uppercase;
  }
  .nav-links a{
    text-decoration:none;
    color:var(--ink);
    position:relative;
    padding-bottom:4px;
  }
  .nav-links a::after{
    content:"";
    position:absolute;
    left:0; right:0; bottom:0;
    height:2px;
    background:var(--accent);
    transform:scaleX(0);
    transform-origin:left;
    transition:transform .25s ease;
  }
  .nav-links a:hover::after,
  .nav-links a:focus-visible::after{ transform:scaleX(1); }
  .nav-links a:focus-visible{ outline:2px solid var(--accent); outline-offset:3px; }

  @media (max-width:640px){
    .nav-links{ display:none; }
  }

  /* ---------- hero ---------- */
  .hero{
    padding-top:clamp(64px, 14vh, 140px);
    padding-bottom:clamp(56px, 10vh, 96px);
    border-bottom:1px solid var(--hairline-soft);
  }
  .hero-label{
    font-family:var(--mono);
    font-size:12px;
    letter-spacing:0.14em;
    text-transform:uppercase;
    color:var(--accent);
    margin-bottom:18px;
  }
  h1.hero-title{
    font-family:var(--display);
    font-weight:600;
    font-size:clamp(40px, 8vw, 96px);
    line-height:0.98;
    letter-spacing:-0.02em;
    margin:0 0 28px 0;
  }
  h1.hero-title em{
    font-style:normal;
    color:var(--accent);
  }
  .hero-sub{
    max-width:560px;
    font-size:clamp(16px, 2vw, 19px);
    line-height:1.6;
    color:#2B2B2B;
    margin:0 0 36px 0;
  }
  .hero-meta{
    display:flex;
    flex-wrap:wrap;
    gap:32px;
    font-family:var(--mono);
    font-size:12px;
    letter-spacing:0.06em;
    text-transform:uppercase;
    color:var(--grey);
  }
  .hero-meta strong{
    display:block;
    color:var(--ink);
    font-family:var(--body);
    text-transform:none;
    letter-spacing:0;
    font-size:14px;
    margin-bottom:4px;
  }

  /* ---------- generic section ---------- */
  section.doc-section{
    padding-top:clamp(56px, 9vh, 100px);
    padding-bottom:clamp(56px, 9vh, 100px);
    border-bottom:1px solid var(--hairline-soft);
  }
  .doc-heading{
    display:flex;
    align-items:flex-end;
    justify-content:space-between;
    gap:24px;
    margin-top:18px;
    margin-bottom:36px;
    flex-wrap:wrap;
  }
  .doc-heading h2{
    font-family:var(--display);
    font-weight:600;
    font-size:clamp(28px, 4vw, 44px);
    letter-spacing:-0.01em;
    margin:0;
  }
  .doc-desc{
    max-width:420px;
    font-size:15px;
    line-height:1.6;
    color:var(--grey);
    margin:0;
  }

  /* ---------- technical frame for embedded PDFs ---------- */
  .blueprint-frame{
    position:relative;
    padding:22px;
    border:1px solid var(--hairline);
  }
  .blueprint-frame::before,
  .blueprint-frame::after,
  .blueprint-frame .corner-tl,
  .blueprint-frame .corner-br{
    content:"";
    position:absolute;
    width:18px;
    height:18px;
  }
  .reg-mark{
    position:absolute;
    width:22px;
    height:22px;
    pointer-events:none;
  }
  .reg-mark::before,
  .reg-mark::after{
    content:"";
    position:absolute;
    background:var(--accent);
  }
  .reg-mark::before{ width:100%; height:2px; top:50%; transform:translateY(-50%); }
  .reg-mark::after{ height:100%; width:2px; left:50%; transform:translateX(-50%); }
  .reg-mark.tl{ top:-11px; left:-11px; }
  .reg-mark.tr{ top:-11px; right:-11px; }
  .reg-mark.bl{ bottom:-11px; left:-11px; }
  .reg-mark.br{ bottom:-11px; right:-11px; }

  .pdf-scroll-viewer{
    position:relative;
    width:100%;
    max-height:78vh;
    overflow-y:auto;
    overflow-x:hidden;
    background:#F4F4F4;
    border:1px solid var(--hairline-soft);
    -webkit-overflow-scrolling:touch;
  }
  .pdf-scroll-viewer[data-orientation="portrait"]{
    max-width:640px;
    margin:0 auto;
  }
  .pdf-scroll-inner{
    display:flex;
    flex-direction:column;
    align-items:center;
    gap:14px;
    padding:14px;
  }
  .pdf-page{
    position:relative;
    width:100%;
    background:#fff;
    display:flex;
  }
  .pdf-page img{
    display:block;
    width:100%;
    height:auto;
  }
  .pdf-expand-btn{
    position:absolute;
    top:12px;
    right:12px;
    width:32px;
    height:32px;
    border:1px solid var(--hairline);
    background:rgba(255,255,255,0.92);
    color:var(--ink);
    display:flex;
    align-items:center;
    justify-content:center;
    cursor:pointer;
    padding:0;
    z-index:2;
    transition:background .18s ease, color .18s ease, border-color .18s ease;
  }
  .pdf-expand-btn:hover{
    background:var(--accent);
    border-color:var(--accent);
    color:#fff;
  }
  .pdf-expand-btn:focus-visible{
    outline:2px solid var(--accent);
    outline-offset:2px;
  }
  .pdf-scroll-viewer.is-fullscreen{
    max-height:none;
    max-width:none;
    width:100vw;
    height:100vh;
    margin:0;
    background:#000;
  }
  .pdf-scroll-viewer.is-fullscreen .pdf-page{
    background:#000;
  }
  .pdf-scroll-viewer.is-fullscreen .pdf-expand-btn{
    background:rgba(0,0,0,0.6);
    color:#fff;
    border-color:rgba(255,255,255,0.4);
  }

  .doc-footer-row{
    display:flex;
    justify-content:space-between;
    align-items:center;
    margin-top:16px;
    font-family:var(--mono);
    font-size:11px;
    letter-spacing:0.06em;
    text-transform:uppercase;
    color:var(--grey);
    flex-wrap:wrap;
    gap:10px;
  }
  .download-link{
    text-decoration:none;
    color:var(--ink);
    border-bottom:1px solid var(--accent);
    padding-bottom:2px;
    font-family:var(--mono);
    font-size:11px;
    letter-spacing:0.06em;
    text-transform:uppercase;
  }
  .download-link:hover{ color:var(--accent); }

  /* ---------- contact / footer ---------- */
  .contact{
    padding-top:clamp(64px, 12vh, 120px);
    padding-bottom:clamp(40px, 8vh, 80px);
  }
  .contact-eyebrow{
    font-family:var(--mono);
    font-size:12px;
    letter-spacing:0.14em;
    text-transform:uppercase;
    color:var(--grey);
    margin-bottom:18px;
  }
  .contact h2{
    font-family:var(--display);
    font-weight:600;
    font-size:clamp(36px, 7vw, 80px);
    line-height:1;
    letter-spacing:-0.02em;
    margin:0 0 36px 0;
  }
  .contact h2 a{
    text-decoration:none;
    border-bottom:3px solid var(--accent);
    transition:color .2s ease;
  }
  .contact h2 a:hover{ color:var(--accent); }

  .contact-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit, minmax(180px,1fr));
    gap:24px;
    margin-bottom:48px;
    max-width:640px;
  }
  .contact-grid div strong{
    display:block;
    font-family:var(--mono);
    font-size:11px;
    letter-spacing:0.1em;
    text-transform:uppercase;
    color:var(--grey);
    margin-bottom:6px;
  }
  .contact-grid div a, .contact-grid div span{
    font-size:15px;
    text-decoration:none;
  }
  .contact-grid div a:hover{ color:var(--accent); }

  footer{
    border-top:1px solid var(--hairline-soft);
    padding-top:24px;
    padding-bottom:24px;
    display:flex;
    justify-content:space-between;
    flex-wrap:wrap;
    gap:10px;
    font-family:var(--mono);
    font-size:11px;
    letter-spacing:0.06em;
    text-transform:uppercase;
    color:var(--grey);
  }

  ::selection{ background:var(--accent); color:#fff; }