/* Chalk — chalkcalc.com · construction calculator */
:root{
  --blue:#388FE1; --blue-deep:#1B5E9E; --blue-ink:#123C66; --blue-soft:#E8F2FC;
  --yellow:#FFB800; --yellow-dark:#E5A600; --yellow-soft:#FFF4D6;
  --ink:#1E2228; --ink-soft:#3A414B; --muted:#6B7280;
  --paper:#FFFFFF; --bg:#F7F9FB; --line:rgba(30,34,40,.09);
  --sans:-apple-system,BlinkMacSystemFont,'SF Pro Text','Segoe UI',Roboto,Helvetica,Arial,sans-serif;
  --mono:ui-monospace,'SF Mono',SFMono-Regular,Menlo,Consolas,monospace;
  --shadow:0 20px 60px rgba(18,60,102,.16);
  --shadow-soft:0 10px 30px rgba(18,60,102,.08);
  --radius:18px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:var(--sans);color:var(--ink);background:var(--bg);line-height:1.6;overflow-x:hidden;-webkit-font-smoothing:antialiased}
img{max-width:100%;display:block}
a{color:var(--blue-deep);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1120px;margin:0 auto;padding:0 24px}

/* ---------- nav ---------- */
.nav{position:sticky;top:0;z-index:50;background:rgba(247,249,251,.92);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
.nav-inner{display:flex;align-items:center;justify-content:space-between;height:70px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:22px;color:var(--ink);letter-spacing:-.4px}
.brand:hover{text-decoration:none}
.brand img{width:36px;height:36px;border-radius:9px;box-shadow:0 3px 10px rgba(30,34,40,.16)}
.nav-links{display:flex;align-items:center;gap:26px;font-weight:500;font-size:15px}
.nav-links a{color:var(--ink-soft)}
.nav-links a:hover{color:var(--blue-deep);text-decoration:none}
.btn{display:inline-flex;align-items:center;gap:8px;background:var(--yellow);color:var(--ink) !important;border-radius:10px;padding:11px 22px;font-weight:700;font-size:15px;transition:transform .15s ease,box-shadow .15s ease;box-shadow:0 6px 18px rgba(255,184,0,.35)}
.btn:hover{transform:translateY(-2px);text-decoration:none;box-shadow:0 10px 24px rgba(255,184,0,.45)}
@media(max-width:760px){.nav-links a:not(.btn){display:none}}

/* ---------- hero ---------- */
.hero{position:relative;overflow:hidden;padding:80px 0 72px;background:linear-gradient(160deg,var(--blue-ink) 0%,var(--blue-deep) 55%,var(--blue) 120%);color:#fff}
.hero::before{content:"";position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.06) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.06) 1px,transparent 1px);background-size:48px 48px;pointer-events:none}
.hero::after{content:"";position:absolute;left:-4%;right:-4%;top:58%;border-top:2px dashed rgba(255,184,0,.4);transform:rotate(-3deg);pointer-events:none}
.hero-inner{display:grid;grid-template-columns:1.05fr .95fr;gap:48px;align-items:center;position:relative;z-index:2}
.kicker{display:inline-block;font-size:12.5px;font-weight:800;letter-spacing:3px;text-transform:uppercase;color:var(--yellow);margin-bottom:16px}
.hero h1{font-size:clamp(40px,5.6vw,66px);line-height:1.05;font-weight:800;letter-spacing:-1.8px}
.hero h1 .u{color:var(--yellow)}
.hero .sub{font-size:19px;color:rgba(255,255,255,.85);margin:22px 0 26px;max-width:520px}
.hero .sub strong{color:#fff;font-weight:700}
.pills{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:30px}
.pill{display:inline-flex;align-items:center;gap:8px;background:rgba(255,255,255,.1);border:1px solid rgba(255,255,255,.22);border-radius:999px;padding:8px 15px;font-size:13.5px;font-weight:600;color:#fff}
.pill svg{width:15px;height:15px;flex:none}
.store-badge{display:inline-block;transition:transform .15s ease}
.store-badge:hover{transform:translateY(-2px)}
.hero-note{font-size:14px;color:rgba(255,255,255,.65);margin-top:14px}

/* ---------- phone mockup (pure CSS) ---------- */
.phone-scene{position:relative;display:flex;justify-content:center;padding:8px 0}
.phone{width:min(300px,78vw);background:#0D1117;border-radius:44px;padding:12px;box-shadow:var(--shadow),inset 0 0 0 2px rgba(255,255,255,.08);transform:rotate(2deg)}
.phone .screen{background:#14181E;border-radius:34px;overflow:hidden}
.phone .notch{width:110px;height:26px;background:#0D1117;border-radius:0 0 16px 16px;margin:0 auto}
.calc-display{padding:26px 20px 14px;text-align:right}
.calc-expr{font-family:var(--mono);font-size:14px;color:#8B949E;letter-spacing:.3px}
.calc-result{font-family:var(--mono);font-size:27px;font-weight:700;color:#fff;margin-top:6px;letter-spacing:-.5px}
.calc-result sup{font-size:14px}
.calc-metric{display:inline-block;font-family:var(--mono);font-size:14px;font-weight:600;color:var(--yellow);background:rgba(255,184,0,.12);border:1px solid rgba(255,184,0,.35);border-radius:8px;padding:3px 10px;margin-top:9px}
.calc-keys{display:grid;grid-template-columns:repeat(4,1fr);gap:7px;padding:12px 14px 18px}
.key{background:#232A33;color:#E6EDF3;border-radius:11px;text-align:center;padding:11px 0;font-size:15px;font-weight:600;font-family:var(--mono)}
.key.unit{background:var(--blue-deep);color:#fff;font-size:13px}
.key.frac{background:#2E3742;color:var(--yellow);font-size:13px}
.key.op{background:#2E3742;color:var(--blue);font-size:17px}
.key.eq{background:var(--yellow);color:var(--ink);font-size:17px}
.float-card{position:absolute;background:#fff;border-radius:13px;box-shadow:var(--shadow);padding:11px 15px;font-size:13px;line-height:1.4;color:var(--ink);z-index:4}
.float-card .t{font-weight:700;font-size:13.5px}
.float-card .s{color:var(--muted);font-size:12px}

/* ---------- sections ---------- */
section{padding:88px 0}
.sec-head{text-align:center;max-width:680px;margin:0 auto 52px}
h2.title{font-size:clamp(30px,4vw,46px);line-height:1.12;font-weight:800;letter-spacing:-1.2px;margin:12px 0 14px}
h2.title .u{color:var(--blue)}
p.lead{font-size:17.5px;color:var(--ink-soft)}
.alt{background:var(--paper)}
section .kicker{color:var(--blue-deep)}

/* trust strip */
.trust{padding:0;background:var(--paper)}
.trust-inner{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;padding:32px 0;border-bottom:1px solid var(--line)}
.trust-item{display:flex;gap:14px;align-items:flex-start}
.trust-item .ic{flex:none;width:42px;height:42px;border-radius:12px;display:flex;align-items:center;justify-content:center}
.trust-item .ic svg{width:20px;height:20px}
.ic.i-blue{background:var(--blue-soft);color:var(--blue-deep)}
.ic.i-yellow{background:var(--yellow-soft);color:#9A6B00}
.ic.i-ink{background:#E9EBEE;color:var(--ink)}
.trust-item .t{font-weight:700;font-size:15.5px;line-height:1.3}
.trust-item .s{font-size:13.5px;color:var(--muted);margin-top:3px}

/* features */
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.card{background:var(--bg);border:1px solid var(--line);border-radius:var(--radius);padding:26px;display:flex;flex-direction:column;gap:15px;transition:transform .2s ease,box-shadow .2s ease}
.card:hover{transform:translateY(-4px);box-shadow:var(--shadow-soft)}
.card h3{font-size:20px;font-weight:700;letter-spacing:-.3px}
.card p{font-size:15px;color:var(--ink-soft)}
.card .tag{display:inline-block;font-size:10.5px;font-weight:800;letter-spacing:1.6px;text-transform:uppercase;background:var(--ink);color:var(--yellow);border-radius:999px;padding:4px 10px;margin-left:8px;vertical-align:2px}
.viz{height:140px;border-radius:13px;position:relative;overflow:hidden;display:flex;align-items:center;justify-content:center;background:var(--paper);border:1px solid var(--line)}
.viz.dark{background:linear-gradient(150deg,#171C22,#242B34)}
.viz.blueprint{background:var(--blue-deep);background-image:linear-gradient(rgba(255,255,255,.09) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.09) 1px,transparent 1px);background-size:22px 22px}
.viz .mono{font-family:var(--mono)}
.viz-keypad{display:grid;grid-template-columns:repeat(4,1fr);gap:5px;padding:16px 30px}
.viz-keypad span{background:#232A33;color:#E6EDF3;border-radius:7px;text-align:center;padding:7px 0;font-size:11px;font-weight:600;font-family:var(--mono);min-width:44px}
.viz-keypad .u{background:var(--blue-deep)}
.viz-keypad .f{color:var(--yellow)}
.chips{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;max-width:860px;margin:0 auto}
.chipc{background:var(--paper);border:1px solid var(--line);border-radius:999px;padding:9px 18px;font-size:14.5px;font-weight:600;color:var(--ink-soft);box-shadow:var(--shadow-soft)}
.chipc.hl{border-color:var(--yellow);background:var(--yellow-soft);color:#7A5500}

/* metric band */
.split{display:grid;grid-template-columns:1fr 1fr;gap:52px;align-items:center}
.split h2.title{text-align:left}
.split .kicker{margin-bottom:0}
.split ul{list-style:none;margin-top:20px}
.split li{padding:9px 0 9px 34px;position:relative;font-size:16px;color:var(--ink-soft)}
.split li::before{content:"✓";position:absolute;left:0;top:9px;font-weight:800;color:var(--blue);width:22px;text-align:center}
.dual-card{background:var(--blue-ink);border-radius:22px;padding:34px 32px;color:#fff;box-shadow:var(--shadow);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:34px 34px}
.dual-card .lbl{font-size:11.5px;font-weight:800;letter-spacing:2.4px;text-transform:uppercase;color:rgba(255,255,255,.55)}
.dual-card .big{font-family:var(--mono);font-size:clamp(26px,3.4vw,36px);font-weight:700;margin:6px 0 20px;letter-spacing:-.5px}
.dual-card .big.yellow{color:var(--yellow)}
.dual-card .rule{border-top:1px dashed rgba(255,255,255,.25);margin:18px 0}
.dual-card .note{font-size:13.5px;color:rgba(255,255,255,.6)}

/* dark band (offline / privacy) */
.dark-band{background:var(--ink);color:#fff}
.dark-band .kicker{color:var(--yellow)}
.dark-band h2.title{color:#fff}
.dark-band p.lead{color:rgba(255,255,255,.72)}
.dark-band .grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-top:8px}
.dark-band .dcard{background:rgba(255,255,255,.05);border:1px solid rgba(255,255,255,.12);border-radius:var(--radius);padding:28px 26px}
.dark-band .dcard .ic{width:44px;height:44px;border-radius:12px;background:rgba(255,184,0,.14);color:var(--yellow);display:flex;align-items:center;justify-content:center;margin-bottom:16px}
.dark-band .dcard .ic svg{width:21px;height:21px}
.dark-band .dcard h3{font-size:18.5px;font-weight:700;margin-bottom:8px}
.dark-band .dcard p{font-size:14.5px;color:rgba(255,255,255,.72)}
.dark-band a{color:var(--yellow)}

/* pricing */
.plans{display:grid;grid-template-columns:1fr 1fr;gap:24px;max-width:820px;margin:0 auto 34px;align-items:stretch}
.plan{border-radius:22px;padding:34px 32px;background:var(--bg);border:1px solid var(--line)}
.plan .ph{font-size:12px;font-weight:800;letter-spacing:2.2px;text-transform:uppercase;color:var(--muted);margin-bottom:8px}
.plan .price{font-size:clamp(30px,3.4vw,40px);font-weight:800;letter-spacing:-1px;line-height:1.1}
.plan .per{font-size:14px;color:var(--muted);margin:6px 0 20px}
.plan ul{list-style:none}
.plan li{padding:7px 0 7px 30px;position:relative;font-size:15px;line-height:1.45;color:var(--ink-soft)}
.plan li::before{content:"✓";position:absolute;left:0;top:7px;font-weight:800;color:var(--blue);width:20px;text-align:center}
.plan.pro{background:var(--ink);color:#fff;border:none;box-shadow:0 30px 70px rgba(30,34,40,.35);position:relative}
.plan.pro .ph{color:var(--yellow)}
.plan.pro li{color:rgba(255,255,255,.85)}
.plan.pro li::before{color:var(--yellow)}
.plan.pro .per{color:rgba(255,255,255,.6)}
.plan .ribbon{position:absolute;top:-14px;right:26px;background:var(--yellow);color:#6B4A00;font-size:11px;font-weight:800;letter-spacing:1.4px;text-transform:uppercase;border-radius:999px;padding:7px 14px;box-shadow:0 6px 16px rgba(0,0,0,.25)}
.pricing-note{max-width:640px;margin:0 auto;text-align:center;font-size:14.5px;color:var(--muted)}
.pricing-note strong{color:var(--ink)}

/* faq */
.faq{max-width:760px;margin:0 auto}
.faq details{background:var(--paper);border:1px solid var(--line);border-radius:14px;margin-bottom:12px;overflow:hidden}
.faq summary{cursor:pointer;padding:19px 24px;font-weight:700;font-size:16px;list-style:none;display:flex;justify-content:space-between;align-items:center;gap:16px}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";font-size:24px;color:var(--blue);font-weight:400;flex:none;line-height:1}
.faq details[open] summary::after{content:"–"}
.faq .a{padding:0 24px 20px;color:var(--ink-soft);font-size:15px}

/* cta band */
.cta-band{background:linear-gradient(150deg,var(--blue-deep) 0%,var(--blue-ink) 100%);color:#fff;position:relative;overflow:hidden}
.cta-band::before{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:44px 44px}
.cta-band .wrap{position:relative;z-index:2;text-align:center}
.cta-band h2.title{color:#fff}
.cta-band p.lead{color:rgba(255,255,255,.85);max-width:520px;margin:0 auto 32px}
.cta-band .hero-note{color:rgba(255,255,255,.65)}

/* footer */
footer{background:var(--ink);color:rgba(255,255,255,.75);padding:58px 0 40px;font-size:15px}
.foot{display:flex;flex-wrap:wrap;justify-content:space-between;gap:32px;align-items:flex-start}
.foot .brand{color:#fff}
.foot p{margin-top:12px;max-width:290px;font-size:14px;color:rgba(255,255,255,.6)}
.foot a{color:rgba(255,255,255,.82)}
.foot .cols{display:flex;gap:56px}
.foot h4{color:#fff;font-size:12.5px;letter-spacing:1.8px;text-transform:uppercase;margin-bottom:12px;font-weight:700}
.foot li{list-style:none;padding:4px 0;font-size:14.5px}
.copyright{margin-top:36px;padding-top:22px;border-top:1px solid rgba(255,255,255,.12);font-size:13px;color:rgba(255,255,255,.45)}

/* legal pages */
.legal{max-width:760px;margin:0 auto;padding:60px 24px 92px}
.legal h1{font-size:40px;font-weight:800;letter-spacing:-1px;margin-bottom:8px}
.legal .date{color:var(--muted);margin-bottom:34px;font-size:15px}
.legal h2{font-size:23px;font-weight:700;margin:34px 0 10px;letter-spacing:-.3px}
.legal p,.legal li{font-size:16px;color:var(--ink-soft);margin-bottom:12px}
.legal ul{padding-left:22px}
.legal .card{background:var(--paper);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow-soft);padding:24px 28px;margin:22px 0;display:block;height:auto}
.legal .card:hover{transform:none;box-shadow:var(--shadow-soft)}
.legal .card.warn{border-left:5px solid var(--yellow);background:var(--yellow-soft)}
.legal .card.warn strong{color:var(--ink)}

@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}

/* responsive */
@media(max-width:900px){.grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:860px){
  section{padding:60px 0}
  .hero{padding:52px 0 60px}
  .hero-inner{grid-template-columns:1fr;gap:52px}
  .hero .sub{font-size:17px}
  .phone{transform:rotate(0)}
  .trust-inner{grid-template-columns:1fr;gap:20px;padding:26px 0}
  .split{grid-template-columns:1fr;gap:40px}
  .plans{grid-template-columns:1fr}
  .dark-band .grid3{grid-template-columns:1fr}
  .foot .cols{flex-wrap:wrap;gap:26px 44px}
  .foot a{word-break:break-word}
  .legal h1{font-size:33px}
}
@media(max-width:600px){
  .grid{grid-template-columns:1fr}
  .float-card{display:none}
}