/* ============================================================
   Стили страницы "Проектирование сетей газоснабжения"
   Все селекторы вложены в .gas-page — не затрагивают остальной сайт
   ============================================================ */

.background-gas {
    background-image: radial-gradient(56.88% 100% at 50% 0,hsla(0,0%,100%,.2) 0,hsla(0,0%,100%,0) 100%),linear-gradient(178.76deg,rgba(46,21,8,.56) 1.06%,rgba(0,0,0,.8) 98.94%),url(https://xn----7sbbaadx1cycag5af.xn--p1ai/wp-content/uploads/2026/07/hero_proect_gaz_teplo.jpg);
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

.gas-page { --gas-accent: #FF7A29; --gas-line: rgba(255,255,255,0.12); --gas-panel: rgba(255,255,255,0.04); --gas-muted: rgba(255,255,255,0.6); }

/* ---------- Карточки-акценты ---------- */
.gas-highlight {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 28px 0 8px;
}
.gas-highlight__card {
  border: 1px solid var(--gas-line);
  background: var(--gas-panel);
  padding: 18px 20px 20px;
  transition: border-color .25s ease, transform .25s ease;
}
.gas-highlight__card:hover { border-color: var(--gas-accent); transform: translateY(-2px); }
.gas-highlight__label {
  display: block; font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--gas-accent); margin-bottom: 8px;
}
.gas-highlight__card strong { display: block; font-size: 16px; line-height: 1.35; color: #fff; }

@media (max-width: 640px) {
  .gas-highlight { grid-template-columns: 1fr; }
}

/* ---------- Навигация по этапам ---------- */
.gas-process {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  position: relative;
  margin: 32px 0 36px;
}
.gas-process::before {
  content: '';
  position: absolute; top: 17px; left: 8%; right: 8%; height: 1px;
  background-image: linear-gradient(90deg, var(--gas-line) 0 8px, transparent 8px 14px);
  background-size: 14px 1px; background-repeat: repeat-x;
}
.gas-process__node { text-align: center; text-decoration: none; position: relative; z-index: 1; }
.gas-process__dot {
  display: flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; margin: 0 auto 10px; border-radius: 50%;
  border: 1px solid var(--gas-line); background: #0d0d0d; color: var(--gas-muted);
  font-size: 12px; transition: border-color .2s, color .2s;
}
.gas-process__node:hover .gas-process__dot { border-color: var(--gas-accent); color: var(--gas-accent); }
.gas-process__label { display: block; font-size: 12.5px; color: var(--gas-muted); line-height: 1.3; }

@media (max-width: 640px) {
  .gas-process { grid-template-columns: repeat(2, 1fr); row-gap: 22px; }
  .gas-process::before { display: none; }
}

/* ---------- Блок этапа ---------- */
.gas-block { margin: 40px 0; padding-top: 8px; }
.gas-block__head {
  display: flex; align-items: baseline; justify-content: space-between; gap: 16px;
  border-bottom: 1px solid var(--gas-line); padding-bottom: 10px; margin-bottom: 16px; flex-wrap: wrap;
}
.gas-block__head h3 { font-size: 20px; color: #fff; margin: 0; }
.gas-block__num { font-size: 12px; letter-spacing: 0.08em; color: var(--gas-accent); }
.gas-block__note { color: var(--gas-muted); margin-bottom: 18px; }
.gas-footnote { color: var(--gas-muted); font-size: 13px; margin-top: 16px; }

/* ---------- Аккордеон ---------- */
.gas-accordion { display: grid; gap: 10px; }
.gas-accordion details {
  background: var(--gas-panel);
  border: 1px solid var(--gas-line);
}
.gas-accordion summary {
  cursor: pointer; list-style: none;
  padding: 16px 18px;
  display: flex; align-items: center; justify-content: space-between; gap: 14px;
  font-size: 15px; font-weight: 600; color: #fff;
}
.gas-accordion summary::-webkit-details-marker { display: none; }
.gas-accordion__icon {
  flex: none; width: 20px; height: 20px; position: relative;
  border: 1px solid var(--gas-line); border-radius: 50%;
  transition: border-color .2s, transform .3s;
}
.gas-accordion__icon::before, .gas-accordion__icon::after {
  content: ''; position: absolute; background: var(--gas-muted); transition: background .2s;
}
.gas-accordion__icon::before { top: 50%; left: 4px; right: 4px; height: 1px; transform: translateY(-50%); }
.gas-accordion__icon::after { left: 50%; top: 4px; bottom: 4px; width: 1px; transform: translateX(-50%); }
.gas-accordion details[open] .gas-accordion__icon { border-color: var(--gas-accent); transform: rotate(45deg); }
.gas-accordion details[open] .gas-accordion__icon::before,
.gas-accordion details[open] .gas-accordion__icon::after { background: var(--gas-accent); }
.gas-accordion details[open] summary { border-bottom: 1px solid var(--gas-line); }
.gas-accordion .sit-list { padding: 16px 18px 18px; margin: 0; }