/* RETURA — retura.ru. Константы по мини-гайду 1.0 */
:root {
  --ink: #1C2126;
  --paper: #F3F1EC;
  --steel: #5E6770;
  --text2: #3A424A;
  --line: #D8D4CC;
  --heat: #B85A24;
  --heat-l: #E08A4F;
  --power: #0F7C82;
  --power-l: #3CC4C4;
  --muted-on-dark: #B9BEC4;
  --display: 'Unbounded', 'Arial Black', sans-serif;
  --body: 'Golos Text', Arial, sans-serif;
  --mono: 'JetBrains Mono', Consolas, monospace;
  --wrap: 1200px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 84px; }
body { margin: 0; background: #FFFFFF; color: var(--ink); font: 400 17px/1.6 var(--body); -webkit-font-smoothing: antialiased; }
img { display: block; max-width: 100%; height: auto; }
a { color: var(--ink); }
a:hover { color: var(--heat); }
h1, h2, h3 { margin: 0; }
h1, h2 { font-family: var(--display); font-weight: 600; letter-spacing: -0.015em; text-wrap: balance; }
h1 { font-size: clamp(34px, 4.6vw, 56px); line-height: 1.1; }
h2 { font-size: clamp(26px, 3vw, 38px); line-height: 1.15; margin-bottom: 36px; }
h3 { font-size: 18px; line-height: 1.35; font-weight: 600; }
p { margin: 0; }
.mono { font-family: var(--mono); }
.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 24px; }

.eyebrow { font-size: 12px; letter-spacing: .2em; text-transform: uppercase; font-weight: 500; color: var(--heat); margin-bottom: 16px; }
.eyebrow--dark { color: var(--heat-l); }
.lead { font-size: 19px; line-height: 1.55; color: var(--text2); max-width: 580px; }
.body { color: var(--text2); max-width: 620px; }
.body + .body { margin-top: 14px; }
.small { font-size: 14px; color: var(--steel); margin-top: 20px; }
.note { font-size: 13px; color: var(--steel); }
.t-heat { color: var(--heat); }
.t-power { color: var(--power); }

/* Кнопки: высота ≥ 44 px */
.btn { display: inline-flex; align-items: center; min-height: 52px; padding: 0 24px; border-radius: 3px; font: 600 16px/1 var(--body); text-decoration: none; cursor: pointer; border: 0; }
.btn--primary { background: var(--heat); color: #FFFFFF; }
.btn--primary:hover { background: #9E4C1D; color: #FFFFFF; }
.btn--ghost { min-height: 44px; padding: 0 18px; border: 1.5px solid var(--ink); background: transparent; font-weight: 500; font-size: 15px; }
.btn--ghost:hover { border-color: var(--heat); }
.btn--link { padding: 0 4px; border-bottom: 1.5px solid var(--ink); border-radius: 0; font-weight: 500; min-height: 44px; }

/* Шапка */
.top { position: sticky; top: 0; z-index: 10; background: rgba(243, 241, 236, .94); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.top__in { height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand img { width: 150px; }
.nav { display: flex; gap: 32px; font-size: 15px; }
.nav a { text-decoration: none; }

/* Первый экран */
.hero { background: var(--paper); }
.hero__in { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 48px; align-items: center; padding-top: 72px; padding-bottom: 80px; }
.hero__text { display: flex; flex-direction: column; gap: 24px; }
.hero__text .eyebrow { margin-bottom: 0; }
.hero__cta { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; margin-top: 4px; }
.hero__fig { margin: 0; }
.hero__fig svg { width: 100%; height: auto; }

/* Схема */
.box { fill: #FFFFFF; stroke: var(--ink); stroke-width: 2; stroke-linejoin: round; }
.box--heat { stroke: var(--heat); }
.box--power { stroke: var(--power); stroke-width: 2.5; }
.box--muted { stroke: var(--steel); }
.ln { fill: none; stroke: var(--ink); stroke-width: 2; stroke-linecap: round; }
.ln--heat { stroke: var(--heat); stroke-width: 3; }
.ln--power { stroke: var(--power); stroke-width: 4; }
.ln--muted { stroke: var(--steel); }
.fill--heat { fill: var(--heat); }
.fill--power { fill: var(--power); }
.lbl { font: 400 14px var(--body); fill: var(--ink); }
.lbl--muted { fill: var(--steel); }
.num { font: 400 13px var(--mono); }
.num--heat { fill: var(--heat); }
.num--power { fill: var(--power); }
.num--muted { fill: var(--steel); }

/* Фирменный приём «переход» */
.transition { display: flex; height: 6px; }
.transition span:first-child { width: 58%; background: var(--heat); }
.transition span:last-child { width: 42%; background: var(--power); }

/* Секции */
.section { padding: 96px 0; }
.section--paper { background: var(--paper); }
.section--dark { background: var(--ink); color: var(--paper); }
.section--dark h3 { color: #FFFFFF; }
.section--dark p { color: var(--muted-on-dark); }
.two { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr); gap: 48px; }
.two h2 { margin-bottom: 20px; }

.facts { list-style: none; margin: 28px 0 0; padding: 0; display: grid; gap: 14px; }
.facts li { padding-top: 14px; border-top: 1px solid var(--line); color: var(--text2); }
.facts b { color: var(--ink); font-weight: 600; }

.grid3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; }
.card { background: #FFFFFF; border: 1px solid var(--line); border-radius: 4px; padding: 24px; display: flex; flex-direction: column; gap: 10px; }
.card p { color: var(--text2); font-size: 15px; line-height: 1.5; }
.card .mono { font-size: 14px; margin-top: auto; padding-top: 8px; }
.card--series { gap: 12px; }
.grid4 { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 20px; }
.series__head { display: flex; justify-content: space-between; align-items: baseline; padding-bottom: 12px; border-bottom: 1px solid var(--line); }
.series__name { font: 600 30px/1 var(--display); }
.series__head .mono { font-size: 16px; margin: 0; padding: 0; }

.why { gap: 40px 48px; }
.why h3 { margin-bottom: 10px; }
.why p { font-size: 15px; line-height: 1.6; }
.why > div { padding-top: 18px; border-top: 2px solid var(--power-l); }
.why > div:nth-child(-n+3) { border-top-color: var(--heat-l); }

.steps { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 20px; }
.steps li { padding-top: 18px; border-top: 1px solid var(--ink); display: flex; flex-direction: column; gap: 10px; }
.steps p { color: var(--text2); font-size: 15px; line-height: 1.55; }
.step__n { color: var(--heat); font-size: 14px; }

/* Форма */
.form { background: #FFFFFF; border: 1px solid var(--line); border-radius: 4px; padding: 28px; display: flex; flex-direction: column; gap: 16px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: 14px; font-weight: 500; }
.field input, .field select, .field textarea { font: 400 16px var(--body); color: var(--ink); padding: 12px 14px; min-height: 48px; border: 1px solid #A9A49A; border-radius: 3px; background: #FFFFFF; }
.field textarea { resize: vertical; }
.field input:focus, .field select:focus, .field textarea:focus, .btn:focus-visible, a:focus-visible { outline: 2px solid var(--power); outline-offset: 2px; }
.row2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.form .btn { justify-content: center; margin-top: 4px; }
.form .small { margin-top: 0; }
.mail { font-weight: 600; }

/* Подвал */
.foot { background: var(--ink); color: var(--muted-on-dark); font-size: 14px; }
.foot__in { padding-top: 48px; padding-bottom: 40px; display: grid; grid-template-columns: auto 1fr auto; gap: 32px; align-items: center; }
.foot__in img { width: 190px; }
.foot a { color: var(--paper); }
.foot a:hover { color: var(--heat-l); }
.foot__meta, .foot__legal { display: flex; flex-direction: column; gap: 6px; }
.foot__legal { text-align: right; }

/* Адаптив */
@media (max-width: 960px) {
  .nav { display: none; }
  .hero__in, .two { grid-template-columns: minmax(0, 1fr); }
  .hero__in { padding-top: 48px; padding-bottom: 56px; }
  .grid3, .grid4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .foot__in { grid-template-columns: minmax(0, 1fr); }
  .foot__legal { text-align: left; }
  .section { padding: 72px 0; }
}
@media (max-width: 600px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px; }
  .top__in { height: 64px; }
  .brand img { width: 124px; }
  .top__cta { font-size: 14px; padding: 0 12px; }
  .grid3, .steps, .row2 { grid-template-columns: minmax(0, 1fr); }
  .grid4 { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
  .form { padding: 20px; }
  .section { padding: 56px 0; }
  h2 { margin-bottom: 28px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

/* Модель энергоблока */
.hero__fig img { width: 100%; height: auto; }
.unit { margin: 56px 0 0; }
.unit svg { width: 100%; height: auto; display: block; }
.unit figcaption { margin-top: 12px; }
@media (max-width: 900px) { .unit { margin-left: -16px; margin-right: -16px; overflow-x: auto; -webkit-overflow-scrolling: touch; } .unit svg { min-width: 880px; } .unit figcaption { padding: 0 16px; } }