/* BTU — btu.917.co.il · V4 Lux 3D design language */
:root {
  color-scheme: dark;
  --btu-studio-black: #020b12;
  --btu-system-navy: #071a2a;
  --btu-glass-blue: #0b3041;
  --btu-smart-teal: #13b8b0;
  --btu-energy-cyan: #43d6e6;
  --btu-cold-silver: #ddf3f5;
  --btu-action-copper: #f28b35;
  --btu-plan-white: #f2f7f7;
  --btu-text-primary: #f2f7f7;
  --btu-text-secondary: #b8cdd3;
  --btu-text-muted: #8ca6b1;
  --btu-border: #315567;
  --btu-surface-raised: rgba(16, 48, 65, 0.82);
  --btu-radius-sm: 8px;
  --btu-radius-md: 14px;
  --btu-radius-lg: 22px;
  --btu-radius-xl: 30px;
  --btu-shadow-card: 0 18px 45px rgba(0, 6, 10, 0.34);
  --btu-shadow-focus: 0 0 0 3px rgba(67, 214, 230, 0.28);
  --btu-font-ui: "Rubik", Arial, sans-serif;
  --btu-font-technical: "IBM Plex Mono", Consolas, monospace;
  --content-max: 1120px;
}

* { box-sizing: border-box; }

html {
  direction: rtl;
  font-family: var(--btu-font-ui);
  background: var(--btu-studio-black);
  color: var(--btu-text-primary);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-size: 17px;
  line-height: 1.65;
  background:
    radial-gradient(circle at 92% 0%, rgba(67, 214, 230, 0.10), transparent 34rem),
    var(--btu-studio-black);
}

:focus-visible { outline: none; box-shadow: var(--btu-shadow-focus); border-radius: 4px; }

.technical, [data-technical] {
  font-family: var(--btu-font-technical);
  direction: ltr;
  unicode-bidi: isolate;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--btu-energy-cyan); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: var(--content-max); margin: 0 auto; padding: 0 24px; }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(2, 11, 18, 0.88);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(49, 85, 103, 0.45);
}
.site-header .container {
  display: flex; align-items: center; gap: 28px;
  height: 68px;
}
.site-logo { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.site-logo img { height: 40px; width: auto; }
.site-nav { display: flex; gap: 22px; align-items: center; flex-wrap: wrap; }
.site-nav a {
  color: var(--btu-text-secondary); font-size: 15px; font-weight: 500;
  text-decoration: none; white-space: nowrap;
}
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--btu-plan-white); }
.header-cta { margin-inline-start: auto; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block; padding: 13px 28px; border-radius: var(--btu-radius-md);
  font-weight: 700; font-size: 16px; text-decoration: none !important;
  border: 1px solid transparent; cursor: pointer; text-align: center;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}
.btn-copper {
  background: linear-gradient(140deg, #f89c4e, var(--btu-action-copper) 55%, #d9741f);
  color: #14202a; box-shadow: 0 10px 26px rgba(242, 139, 53, 0.28);
}
.btn-copper:hover { transform: translateY(-2px); box-shadow: 0 14px 32px rgba(242, 139, 53, 0.38); }
.btn-ghost {
  background: rgba(19, 184, 176, 0.08); color: var(--btu-cold-silver);
  border-color: var(--btu-border);
}
.btn-ghost:hover { background: rgba(19, 184, 176, 0.16); }
.btn-sm { padding: 9px 18px; font-size: 14px; }

/* ---------- Hero ---------- */
.hero {
  position: relative; overflow: hidden;
  padding: 72px 0 84px;
  background:
    radial-gradient(circle at 15% 20%, rgba(19, 184, 176, 0.14), transparent 26rem),
    radial-gradient(circle at 85% 75%, rgba(67, 214, 230, 0.10), transparent 30rem),
    linear-gradient(160deg, #041420 0%, var(--btu-studio-black) 60%);
}
.hero-photo {
  padding: 108px 0 124px;
  background:
    linear-gradient(180deg, rgba(2, 11, 18, 0.5) 0%, rgba(2, 11, 18, 0) 20%, rgba(2, 11, 18, 0) 74%, var(--btu-studio-black) 100%),
    linear-gradient(90deg, rgba(2, 11, 18, 0.32) 0%, rgba(2, 11, 18, 0.1) 28%, rgba(2, 11, 18, 0.5) 55%, rgba(2, 11, 18, 0.9) 82%, var(--btu-studio-black) 100%),
    url("/assets/hero-clean.jpg");
  background-size: auto, auto, cover;
  background-position: center, center, left center;
  background-repeat: no-repeat;
}
.hero-photo .hero-copy { max-width: 560px; }
.hero-photo .hero-desc { max-width: 32rem; }
@media (max-width: 960px) {
  .hero-photo {
    padding: 84px 0 96px;
    background:
      linear-gradient(180deg, rgba(2, 11, 18, 0.72) 0%, rgba(2, 11, 18, 0.55) 45%, var(--btu-studio-black) 100%),
      url("/assets/hero-clean.jpg");
    background-size: auto, cover;
    background-position: center, left 30% center;
  }
  .hero-photo .hero-copy { max-width: 100%; }
}
.hero-grid {
  position: absolute; inset: 0; opacity: 0.13; pointer-events: none;
  background-image:
    linear-gradient(rgba(67, 214, 230, 0.35) 1px, transparent 1px),
    linear-gradient(90deg, rgba(67, 214, 230, 0.35) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse at 50% 30%, #000 15%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse at 50% 30%, #000 15%, transparent 75%);
}
.hero .container { position: relative; display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr); gap: 48px; align-items: center; }
.hero-eyebrow {
  display: inline-block; font-size: 14px; font-weight: 600; letter-spacing: 0.02em;
  color: var(--btu-smart-teal); background: rgba(19, 184, 176, 0.1);
  border: 1px solid rgba(19, 184, 176, 0.35);
  padding: 6px 14px; border-radius: 999px; margin-bottom: 20px;
}
.hero h1 {
  font-size: clamp(34px, 4.6vw, 54px); line-height: 1.15; font-weight: 900;
  margin: 0 0 18px; color: var(--btu-plan-white);
}
.hero h1 em { font-style: normal; color: var(--btu-energy-cyan); }
.hero-desc { font-size: 19px; color: var(--btu-text-secondary); max-width: 34rem; margin: 0 0 30px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; align-items: center; }
.hero-trust { margin-top: 22px; font-size: 15px; color: var(--btu-text-muted); }
.hero-visual img { border-radius: var(--btu-radius-lg); box-shadow: var(--btu-shadow-card); border: 1px solid rgba(49, 85, 103, 0.5); }

/* ---------- Sections ---------- */
section { padding: 72px 0; }
.section-alt { background: linear-gradient(180deg, rgba(7, 26, 42, 0.55), rgba(7, 26, 42, 0.15)); }
.section-head { max-width: 720px; margin: 0 auto 44px; text-align: center; }
.section-head h2 { font-size: clamp(26px, 3.4vw, 38px); font-weight: 800; margin: 0 0 12px; color: var(--btu-plan-white); }
.section-head p { color: var(--btu-text-secondary); font-size: 17px; margin: 0; }
.kicker { color: var(--btu-smart-teal); font-weight: 700; font-size: 14px; letter-spacing: 0.06em; display: block; margin-bottom: 10px; }

/* ---------- Cards ---------- */
.cards { display: grid; gap: 22px; }
.cards-3 { grid-template-columns: repeat(3, 1fr); }
.cards-2 { grid-template-columns: repeat(2, 1fr); }
.card {
  background: var(--btu-surface-raised);
  border: 1px solid rgba(49, 85, 103, 0.5);
  border-radius: var(--btu-radius-lg);
  padding: 28px;
  box-shadow: var(--btu-shadow-card);
}
.card h3 { margin: 0 0 10px; font-size: 20px; font-weight: 700; color: var(--btu-plan-white); }
.card p { margin: 0; color: var(--btu-text-secondary); font-size: 15.5px; }
.card .icon {
  width: 46px; height: 46px; border-radius: 12px; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(140deg, rgba(19, 184, 176, 0.18), rgba(67, 214, 230, 0.10));
  border: 1px solid rgba(19, 184, 176, 0.35);
  margin-bottom: 16px; font-size: 22px;
}
.card-link { display: inline-block; margin-top: 14px; font-weight: 600; font-size: 15px; }

/* ---------- Steps ---------- */
.steps { display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px; counter-reset: step; }
.step {
  background: rgba(7, 26, 42, 0.7); border: 1px solid rgba(49, 85, 103, 0.45);
  border-radius: var(--btu-radius-md); padding: 22px 18px; position: relative;
}
.step .num {
  font-family: var(--btu-font-technical); font-size: 13px; color: var(--btu-energy-cyan);
  display: block; margin-bottom: 8px;
}
.step h3 { font-size: 16.5px; margin: 0 0 6px; color: var(--btu-plan-white); }
.step p { font-size: 14px; color: var(--btu-text-muted); margin: 0; }

/* ---------- Before / After ---------- */
.ba { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.ba-col { border-radius: var(--btu-radius-lg); padding: 28px; border: 1px solid rgba(49, 85, 103, 0.5); }
.ba-before { background: rgba(255, 104, 95, 0.06); border-color: rgba(255, 104, 95, 0.3); }
.ba-after { background: rgba(19, 184, 176, 0.07); border-color: rgba(19, 184, 176, 0.35); }
.ba-col h3 { margin: 0 0 14px; font-size: 18px; }
.ba-before h3 { color: #ff9d96; }
.ba-after h3 { color: var(--btu-smart-teal); }
.ba-col ul { margin: 0; padding-inline-start: 20px; color: var(--btu-text-secondary); font-size: 15.5px; }
.ba-col li { margin-bottom: 8px; }

/* ---------- FAQ ---------- */
.faq { max-width: 780px; margin: 0 auto; }
.faq details {
  background: var(--btu-surface-raised); border: 1px solid rgba(49, 85, 103, 0.5);
  border-radius: var(--btu-radius-md); padding: 4px 22px; margin-bottom: 12px;
}
.faq summary {
  cursor: pointer; font-weight: 700; font-size: 17px; padding: 14px 0; color: var(--btu-plan-white);
  list-style: none; position: relative; padding-inline-end: 28px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+"; position: absolute; inset-inline-end: 0; top: 12px;
  color: var(--btu-smart-teal); font-size: 22px; font-weight: 400;
}
.faq details[open] summary::after { content: "–"; }
.faq details p { color: var(--btu-text-secondary); margin: 0 0 16px; font-size: 15.5px; }

/* ---------- CTA band ---------- */
.cta-band {
  text-align: center; border-radius: var(--btu-radius-xl); padding: 56px 32px;
  background:
    radial-gradient(circle at 20% 15%, rgba(242, 139, 53, 0.12), transparent 22rem),
    linear-gradient(150deg, var(--btu-glass-blue), var(--btu-system-navy));
  border: 1px solid rgba(49, 85, 103, 0.55);
  box-shadow: var(--btu-shadow-card);
}
.cta-band h2 { font-size: clamp(24px, 3.2vw, 34px); margin: 0 0 12px; font-weight: 800; }
.cta-band p { color: var(--btu-text-secondary); margin: 0 auto 28px; max-width: 34rem; }

/* ---------- Signup form ---------- */
.signup-form { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.signup-form input {
  background: rgba(2, 11, 18, 0.6); border: 1px solid var(--btu-border);
  color: var(--btu-plan-white); border-radius: var(--btu-radius-md);
  padding: 13px 18px; font-size: 16px; font-family: inherit; min-width: 260px;
}
.signup-form input::placeholder { color: var(--btu-text-muted); }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid rgba(49, 85, 103, 0.4);
  padding: 48px 0 36px; margin-top: 40px;
  background: rgba(4, 16, 26, 0.7); font-size: 14.5px;
}
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 32px; margin-bottom: 32px; }
.footer-grid h4 { color: var(--btu-plan-white); font-size: 15px; margin: 0 0 12px; }
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: 8px; }
.footer-grid a { color: var(--btu-text-muted); }
.footer-grid a:hover { color: var(--btu-cold-silver); }
.footer-about { color: var(--btu-text-muted); max-width: 30rem; }
.footer-bottom { border-top: 1px solid rgba(49, 85, 103, 0.3); padding-top: 20px; color: var(--btu-text-muted); display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }

/* ---------- Article / inner page ---------- */
.page-hero { padding: 56px 0 40px; }
.page-hero h1 { font-size: clamp(30px, 4vw, 44px); font-weight: 900; margin: 0 0 14px; max-width: 18ch; }
.page-hero .lead { font-size: 19px; color: var(--btu-text-secondary); max-width: 38rem; }
.page-banner { border-radius: var(--btu-radius-lg); box-shadow: var(--btu-shadow-card); border: 1px solid rgba(49, 85, 103, 0.5); margin: 8px 0 24px; }

.article-body { max-width: 760px; margin: 0 auto; }
.article-body h2 { font-size: 27px; font-weight: 800; margin: 44px 0 14px; color: var(--btu-plan-white); }
.article-body h3 { font-size: 21px; font-weight: 700; margin: 32px 0 10px; color: var(--btu-plan-white); }
.article-body p, .article-body li { color: var(--btu-text-secondary); font-size: 17px; }
.article-body ul, .article-body ol { padding-inline-start: 24px; }
.article-body li { margin-bottom: 8px; }
.article-body strong { color: var(--btu-cold-silver); }
.article-body blockquote {
  margin: 24px 0; padding: 18px 22px; border-inline-start: 3px solid var(--btu-smart-teal);
  background: rgba(19, 184, 176, 0.07); border-radius: 0 var(--btu-radius-sm) var(--btu-radius-sm) 0;
  color: var(--btu-cold-silver);
}
.article-meta { color: var(--btu-text-muted); font-size: 14px; margin-bottom: 28px; }
.article-cover { border-radius: var(--btu-radius-lg); box-shadow: var(--btu-shadow-card); margin-bottom: 32px; }

.article-body table { width: 100%; border-collapse: collapse; margin: 20px 0; font-size: 15.5px; }
.article-body th {
  background: var(--btu-glass-blue); color: var(--btu-plan-white); text-align: right;
  padding: 10px 14px; border: 1px solid rgba(49, 85, 103, 0.6);
}
.article-body td { padding: 10px 14px; border: 1px solid rgba(49, 85, 103, 0.45); color: var(--btu-text-secondary); }
.article-body .note {
  background: rgba(242, 139, 53, 0.08); border: 1px solid rgba(242, 139, 53, 0.3);
  border-radius: var(--btu-radius-md); padding: 16px 20px; margin: 24px 0; font-size: 15.5px;
}

/* ---------- Blog cards ---------- */
.blog-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.blog-card {
  background: var(--btu-surface-raised); border: 1px solid rgba(49, 85, 103, 0.5);
  border-radius: var(--btu-radius-lg); overflow: hidden; box-shadow: var(--btu-shadow-card);
  display: flex; flex-direction: column; transition: transform 0.15s ease;
}
.blog-card:hover { transform: translateY(-4px); }
.blog-card img { aspect-ratio: 16/9; object-fit: cover; }
.blog-card .blog-card-body { padding: 20px 22px 24px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.blog-card h3 { margin: 0; font-size: 18px; line-height: 1.4; }
.blog-card h3 a { color: var(--btu-plan-white); }
.blog-card p { margin: 0; color: var(--btu-text-muted); font-size: 14.5px; flex: 1; }
.blog-card .tag { color: var(--btu-smart-teal); font-size: 13px; font-weight: 600; }

/* ---------- Calculator ---------- */
.calc-wrap { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 0.9fr); gap: 32px; align-items: start; }
.calc-form { display: grid; gap: 18px; }
.calc-field label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 15px; color: var(--btu-cold-silver); }
.calc-field input, .calc-field select {
  width: 100%; background: rgba(2, 11, 18, 0.6); border: 1px solid var(--btu-border);
  color: var(--btu-plan-white); border-radius: var(--btu-radius-md);
  padding: 12px 16px; font-size: 16px; font-family: inherit;
}
.calc-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.calc-result {
  position: sticky; top: 90px; text-align: center; padding: 36px 28px;
}
.calc-result .value {
  font-family: var(--btu-font-technical); font-size: clamp(38px, 5vw, 56px);
  font-weight: 700; color: var(--btu-energy-cyan); direction: ltr;
}
.calc-result .unit { font-size: 18px; color: var(--btu-text-muted); }
.calc-result .hp { font-size: 16px; color: var(--btu-cold-silver); margin-top: 6px; }
.calc-note { font-size: 13.5px; color: var(--btu-text-muted); margin-top: 18px; }

/* ---------- Responsive ---------- */
@media (max-width: 960px) {
  .hero .container { grid-template-columns: 1fr; }
  .hero-visual { order: -1; }
  .cards-3 { grid-template-columns: 1fr 1fr; }
  .steps { grid-template-columns: 1fr 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .blog-grid { grid-template-columns: 1fr 1fr; }
  .calc-wrap { grid-template-columns: 1fr; }
  .calc-result { position: static; }
  .site-nav { display: none; }
}
@media (max-width: 620px) {
  .cards-3, .cards-2, .ba, .steps, .blog-grid, .footer-grid { grid-template-columns: 1fr; }
  section { padding: 52px 0; }
  body { font-size: 16px; }
}