:root {
  --navy: #0b1a2e;
  --navy-2: #12263f;
  --navy-3: #1b3453;
  --ink: #14202e;
  --text: #3b4a5c;
  --muted: #647589;
  --line: #e1e7ee;
  --bg: #ffffff;
  --bg-alt: #f3f6f9;
  --accent: #f5a524;
  --accent-ink: #1a1203;
  --accent-hover: #ffb640;
  --cyan: #3cc3e0;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(11, 26, 46, .06), 0 8px 24px rgba(11, 26, 46, .06);
  --font: "Inter", "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 84px; -webkit-text-size-adjust: 100%; }
body { margin: 0; font: 16px/1.6 var(--font); color: var(--text); background: var(--bg); overflow-x: hidden; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; }
h1, h2, h3 { color: var(--ink); line-height: 1.2; margin: 0 0 .5em; letter-spacing: -.01em; }
h1 { font-size: clamp(2rem, 4.6vw, 3.4rem); font-weight: 800; }
h2 { font-size: clamp(1.6rem, 3vw, 2.4rem); font-weight: 800; }
h3 { font-size: 1.125rem; font-weight: 700; }
p { margin: 0 0 1em; }
button, input, select, textarea { font: inherit; color: inherit; }
[hidden] { display: none !important; }
.sprite { position: absolute; width: 0; height: 0; overflow: hidden; }

use, svg use { fill: none; }
.card__icon, .hero__list svg, .contact-list svg, .feature svg, .project__img svg, .project__term svg,
.btn svg, .fab svg { fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }

.container { width: min(1200px, 100% - 32px); margin-inline: auto; }
.container--narrow { width: min(820px, 100% - 32px); }
.eyebrow { font-size: .8rem; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: #c47d06; margin: 0 0 .75em; }
.muted { color: var(--muted); }
.lead { font-size: 1.125rem; }
.hl { color: var(--accent); }

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: .5em; padding: .9em 1.5em; border-radius: 10px; border: 2px solid transparent;
  font-weight: 700; text-decoration: none; cursor: pointer; transition: background .15s, border-color .15s, transform .15s; white-space: nowrap; }
.btn svg { width: 18px; height: 18px; }
.btn--accent { background: var(--accent); color: var(--accent-ink); }
.btn--accent:hover { background: var(--accent-hover); }
.btn--ghost { border-color: rgba(255,255,255,.35); color: #fff; }
.btn--ghost:hover { border-color: #fff; background: rgba(255,255,255,.06); }
.btn--line { border-color: var(--line); background: #fff; color: var(--ink); }
.btn--line:hover { border-color: var(--ink); }
.btn--sm { padding: .6em 1.1em; font-size: .95rem; }
.btn--block { width: 100%; }
.btn:active { transform: translateY(1px); }
.btn:focus-visible, .tab:focus-visible, .chip:focus-visible, summary:focus-visible, a:focus-visible { outline: 3px solid var(--cyan); outline-offset: 2px; }

/* Header */
.header { position: sticky; top: 0; z-index: 50; background: rgba(11, 26, 46, .96); backdrop-filter: blur(8px); color: #fff; border-bottom: 1px solid rgba(255,255,255,.08); }
.header__row { display: flex; align-items: center; gap: 24px; height: 68px; }
.logo { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--accent); flex-shrink: 0; }
.logo__mark { width: 36px; height: 36px; }
.logo__text { color: #fff; font-weight: 800; font-size: 1.15rem; line-height: 1.1; }
.logo__text small { display: block; font-weight: 500; font-size: .72rem; color: #9fb2c8; letter-spacing: .02em; }
.nav { display: flex; gap: 22px; margin-left: auto; }
.nav a { text-decoration: none; color: #c9d6e4; font-weight: 500; font-size: .95rem; }
.nav a:hover { color: #fff; }
.header__cta { display: flex; align-items: center; gap: 16px; }
.header__phone { text-decoration: none; font-weight: 700; white-space: nowrap; }
.burger { display: none; margin-left: auto; width: 44px; height: 44px; border: 0; background: none; cursor: pointer; padding: 10px; }
.burger span { display: block; height: 2px; background: #fff; margin: 5px 0; transition: transform .2s, opacity .2s; }
.burger[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.burger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.burger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Hero */
.hero { position: relative; background: radial-gradient(1200px 600px at 85% 0%, #1d3a60 0%, transparent 60%), var(--navy); color: #c9d6e4; overflow: hidden; }
.hero__grid { position: absolute; inset: 0; opacity: .5;
  background-image: linear-gradient(rgba(60,195,224,.08) 1px, transparent 1px), linear-gradient(90deg, rgba(60,195,224,.08) 1px, transparent 1px);
  background-size: 40px 40px; mask-image: linear-gradient(180deg, #000 30%, transparent); -webkit-mask-image: linear-gradient(180deg, #000 30%, transparent); }
.hero__inner { position: relative; display: grid; grid-template-columns: 1.4fr 1fr; gap: 56px; align-items: center; padding: 88px 0 96px; }
.hero h1 { color: #fff; }
.hero .eyebrow { color: var(--cyan); }
.hero__list { list-style: none; padding: 0; margin: 1.5em 0 2em; display: grid; gap: .5em; }
.hero__list li { display: flex; align-items: center; gap: .6em; color: #e6eef6; }
.hero__list svg { width: 20px; height: 20px; color: var(--accent); stroke-width: 2.4; flex-shrink: 0; }
.hero__actions { display: flex; flex-wrap: wrap; gap: 12px; }
.hero__panel { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; background: rgba(255,255,255,.1); border: 1px solid rgba(255,255,255,.1); border-radius: var(--radius); overflow: hidden; }
.stat { background: var(--navy-2); padding: 28px 24px; }
.stat b { display: block; font-size: 2.4rem; font-weight: 800; color: #fff; line-height: 1; margin-bottom: 8px; font-variant-numeric: tabular-nums; }
.stat span { font-size: .9rem; color: #9fb2c8; }

/* Sections */
.section { padding: 96px 0; }
.section--alt { background: var(--bg-alt); }
.section--dark { background: var(--navy); color: #c9d6e4; }
.section--dark h2, .section--dark h3 { color: #fff; }
.section--dark .eyebrow { color: var(--cyan); }
.section__head { max-width: 720px; margin-bottom: 40px; }

/* Tabs & cards */
.tabs { display: inline-flex; background: var(--bg-alt); border-radius: 12px; padding: 4px; margin-bottom: 28px; flex-wrap: wrap; }
.tab { border: 0; background: none; padding: .7em 1.3em; border-radius: 9px; font-weight: 700; color: var(--muted); cursor: pointer; }
.tab.is-active { background: #fff; color: var(--ink); box-shadow: var(--shadow); }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 20px; }
.card { display: flex; flex-direction: column; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; transition: border-color .2s, box-shadow .2s, transform .2s; }
.card:hover { border-color: #c8d3df; box-shadow: var(--shadow); transform: translateY(-2px); }
.card__icon { width: 44px; height: 44px; padding: 9px; border-radius: 10px; background: #fff4e0; color: #c47d06; margin-bottom: 18px; }
[data-panel="vent"] .card__icon { background: #e3f6fb; color: #1a8aa3; }
.card p { font-size: .95rem; }
.card__price { margin: auto 0 0; padding-top: 12px; border-top: 1px dashed var(--line); font-weight: 800; color: var(--ink); }
.card__price span { font-weight: 500; color: var(--muted); font-size: .9rem; }

/* Calculator */
.calc { display: grid; grid-template-columns: 1fr 340px; gap: 24px; align-items: start; }
.calc__main { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; }
.calc__rows { display: grid; gap: 12px; margin-bottom: 16px; }
.calc-row { display: grid; grid-template-columns: 1fr 120px auto 44px; gap: 10px; align-items: center; }
.calc-row__unit { font-size: .85rem; color: var(--muted); min-width: 80px; }
.calc-row__del { width: 44px; height: 44px; border: 1px solid var(--line); border-radius: 10px; background: #fff; cursor: pointer; color: var(--muted); display: grid; place-items: center; }
.calc-row__del:hover { color: #c0392b; border-color: #c0392b; }
.calc-row__del svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; }
.calc__opts { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 24px; padding-top: 24px; border-top: 1px solid var(--line); }
.calc__opts .check { grid-column: 1 / -1; }
.calc__result { position: sticky; top: 92px; background: var(--navy); color: #c9d6e4; border-radius: var(--radius); padding: 28px; }
.calc__label { font-size: .85rem; text-transform: uppercase; letter-spacing: .1em; margin: 0 0 6px; color: #9fb2c8; }
.calc__sum { font-size: clamp(1.6rem, 3vw, 2rem); font-weight: 800; color: #fff; margin: 0 0 8px; line-height: 1.2; font-variant-numeric: tabular-nums; }
.calc__note { font-size: .9rem; margin-bottom: 20px; }
.calc__small { font-size: .8rem; color: #9fb2c8; text-align: center; margin: 10px 0 0; }

/* Form fields */
.field { display: grid; gap: 6px; }
.field > span { font-size: .85rem; font-weight: 600; color: var(--ink); }
.field em { font-style: normal; color: var(--muted); font-weight: 400; }
input[type="text"], input[type="tel"], input[type="number"], select, textarea {
  width: 100%; min-height: 44px; padding: .65em .85em; border: 1px solid #cdd6e0; border-radius: 10px; background: #fff; color: var(--ink); transition: border-color .15s, box-shadow .15s; }
textarea { resize: vertical; min-height: 96px; }
select { appearance: none; -webkit-appearance: none; padding-right: 2.2em;
  background: #fff url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1.5l5 5 5-5' fill='none' stroke='%23647589' stroke-width='1.8'/%3E%3C/svg%3E") no-repeat right .9em center; }
input:focus, select:focus, textarea:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(60,195,224,.25); }
.is-invalid { border-color: #d64545 !important; }
.check { display: flex; gap: 10px; align-items: flex-start; cursor: pointer; font-size: .95rem; color: var(--ink); }
.check input { width: 20px; height: 20px; margin: 2px 0 0; accent-color: var(--accent); flex-shrink: 0; }
.check--small { font-size: .82rem; color: var(--muted); }
.check--small a { color: var(--ink); }

/* Projects */
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 24px; }
.chip { border: 1px solid var(--line); background: #fff; border-radius: 999px; padding: .5em 1.1em; font-weight: 600; cursor: pointer; color: var(--text); }
.chip.is-active { background: var(--ink); border-color: var(--ink); color: #fff; }
.projects { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.project { border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: #fff; display: flex; flex-direction: column; }
.project__img { aspect-ratio: 16 / 9; display: grid; place-items: center; color: rgba(255,255,255,.9); position: relative;
  background-image: linear-gradient(rgba(255,255,255,.07) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,.07) 1px, transparent 1px), var(--g);
  background-size: 24px 24px, 24px 24px, cover; }
.project__img svg { width: 64px; height: 64px; stroke-width: 1.3; }
.project__img--1 { --g: linear-gradient(135deg, #12263f, #2b5078); }
.project__img--2 { --g: linear-gradient(135deg, #0f3b47, #1f7f92); }
.project__img--3 { --g: linear-gradient(135deg, #3a1d12, #9c4a1c); }
.project__img--4 { --g: linear-gradient(135deg, #1e2140, #4a4f8c); }
.project__img--5 { --g: linear-gradient(135deg, #12343a, #3c8f86); }
.project__img--6 { --g: linear-gradient(135deg, #2a2a2a, #5d6470); }
.project__body { padding: 22px 24px 24px; display: flex; flex-direction: column; flex: 1; }
.project__meta { font-size: .85rem; font-weight: 600; color: #c47d06; margin-bottom: .4em; }
.tags { list-style: none; padding: 0; margin: 0 0 16px; display: flex; flex-wrap: wrap; gap: 6px; }
.tags li { font-size: .8rem; background: var(--bg-alt); border-radius: 6px; padding: 3px 9px; color: var(--text); }
.project__term { margin: auto 0 0; display: flex; gap: 6px; align-items: center; font-size: .88rem; color: var(--muted); }
.project__term svg { width: 16px; height: 16px; }
.project.is-hidden { display: none; }

/* Steps */
.steps { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px; counter-reset: s; }
.steps li { border-top: 2px solid var(--navy-3); padding-top: 20px; position: relative; }
.steps li::before { content: ""; position: absolute; top: -2px; left: 0; width: 40px; height: 2px; background: var(--accent); }
.steps b { display: block; font-size: .85rem; color: var(--cyan); margin-bottom: 10px; letter-spacing: .1em; }
.steps p { font-size: .92rem; color: #9fb2c8; }

/* Features */
.features { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.feature { padding: 4px 0; }
.feature svg { width: 40px; height: 40px; color: #c47d06; margin-bottom: 14px; }
.feature p { font-size: .95rem; }

/* FAQ */
.faq { display: grid; gap: 10px; }
.faq details { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 0 22px; }
.faq summary { list-style: none; cursor: pointer; padding: 18px 32px 18px 0; font-weight: 700; color: var(--ink); position: relative; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: ""; position: absolute; right: 4px; top: 50%; width: 10px; height: 10px; border-right: 2px solid var(--muted); border-bottom: 2px solid var(--muted); transform: translateY(-70%) rotate(45deg); transition: transform .2s; }
.faq details[open] summary::after { transform: translateY(-30%) rotate(-135deg); }
.faq details p { padding-bottom: 18px; margin: 0; }

/* Contacts */
.contacts { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: start; }
.contact-list { list-style: none; padding: 0; margin: 28px 0 0; display: grid; gap: 14px; }
.contact-list li { display: flex; gap: 12px; align-items: center; color: var(--ink); }
.contact-list a { text-decoration: none; font-weight: 600; }
.contact-list a:hover { color: #c47d06; }
.contact-list svg { width: 22px; height: 22px; color: #c47d06; flex-shrink: 0; }
.form { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 32px; box-shadow: var(--shadow); display: grid; gap: 16px; }
.form h3 { font-size: 1.35rem; margin: 0; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.form__status { margin: 0; font-size: .92rem; min-height: 1.4em; }
.form__status.is-ok { color: #1e8a4c; font-weight: 600; }
.form__status.is-err { color: #d64545; }
.form.is-sent { outline: 2px solid #1e8a4c; }

/* Footer */
.footer { background: var(--navy); color: #9fb2c8; padding: 32px 0; font-size: .9rem; }
.footer__row { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.footer__row p { margin: 0; }
.footer a { color: #c9d6e4; }
.footer__small { font-size: .8rem; margin-top: 16px; color: #7488a0; }

.fab { display: none; position: fixed; right: 16px; bottom: 16px; z-index: 40; width: 56px; height: 56px; border-radius: 50%; background: var(--accent); color: var(--accent-ink); place-items: center; box-shadow: 0 6px 20px rgba(0,0,0,.25); }
.fab svg { width: 26px; height: 26px; stroke-width: 2; }

/* Simple page (privacy, 404) */
.page { padding: 64px 0 96px; }
.page h1 { font-size: clamp(1.8rem, 3.5vw, 2.4rem); }
.page h2 { font-size: 1.3rem; margin-top: 1.6em; }
.page li { margin-bottom: .4em; }

/* Responsive */
@media (max-width: 1080px) {
  .nav { gap: 16px; }
  .header__phone { display: none; }
  .steps { grid-template-columns: repeat(3, 1fr); row-gap: 32px; }
  .features { grid-template-columns: repeat(2, 1fr); }
  .projects { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 900px) {
  .burger { display: block; }
  .header__cta { display: none; }
  .nav { position: fixed; inset: 68px 0 auto 0; flex-direction: column; gap: 0; background: var(--navy); padding: 8px 16px 20px; border-bottom: 1px solid rgba(255,255,255,.1);
    transform: translateY(-120%); transition: transform .25s; visibility: hidden; }
  .nav.is-open { transform: none; visibility: visible; }
  .nav a { padding: 14px 4px; border-bottom: 1px solid rgba(255,255,255,.06); font-size: 1.05rem; }
  .hero__inner { grid-template-columns: 1fr; gap: 40px; padding: 56px 0 64px; }
  .calc { grid-template-columns: 1fr; }
  .calc__result { position: static; }
  .contacts { grid-template-columns: 1fr; gap: 40px; }
  .fab { display: grid; }
}
@media (max-width: 640px) {
  .section { padding: 64px 0; }
  .projects, .features { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr 1fr; }
  .calc__main, .form { padding: 20px; }
  .calc__opts { grid-template-columns: 1fr; }
  .calc-row { grid-template-columns: 1fr 88px 44px; }
  .calc-row select { grid-column: 1 / -1; }
  .calc-row__unit { grid-column: 1; grid-row: 2; }
  .stat { padding: 20px 16px; }
  .stat b { font-size: 1.9rem; }
  .hero__actions .btn { flex: 1 1 auto; }
  .tabs { display: flex; width: 100%; flex-wrap: nowrap; }
  .tab { flex: 1 1 0; padding: .7em .5em; font-size: .88rem; line-height: 1.25; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}

.project__img--photo { background: var(--bg-alt); }
.project__img--photo img { width: 100%; height: 100%; object-fit: cover; }