/* =========================================================
   prs-hydrogen.css — PRS Hydrogen project case-study page
   Scoped (prh-*) components layered on the shared design
   system. Reuses tokens from main.css; no global overrides.
   Tactical-telemetry language: dark substrate, orange accent,
   1px structural dividers, mono uppercase metadata, 0 radius.
   ========================================================= */

.prh-wrap { max-width: 1040px; margin: 0 auto; padding: 0 clamp(16px, 4vw, 40px); }

/* ---- Breadcrumb ---------------------------------------- */
.prh-breadcrumb {
  font-family: var(--font-mono);
  font-size: .74rem;
  color: var(--muted);
  margin: 18px 0 26px;
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  letter-spacing: .02em;
}
.prh-breadcrumb a { color: var(--muted); transition: color var(--t); }
.prh-breadcrumb a:hover { color: var(--primary); }
.prh-breadcrumb span { color: var(--subtle); }

/* ---- Hero ---------------------------------------------- */
.prh-hero { margin-bottom: clamp(36px, 6vw, 60px); }
.prh-hero-chip {
  display: inline-flex; align-items: center; gap: 8px; height: 28px; padding: 0 14px;
  background: var(--primary-soft);
  border: 1px solid var(--primary-line); color: var(--primary);
  font-family: var(--font-mono);
  font-size: .68rem; font-weight: 700; letter-spacing: .14em;
  text-transform: uppercase; margin-bottom: 22px;
}
.prh-hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 5.6vw, 3.8rem); font-weight: 900; line-height: .96;
  letter-spacing: -.03em; text-transform: uppercase;
  margin: 0 0 14px;
}
.prh-hero h1 .accent { color: var(--primary); }
.prh-hero-subtitle {
  font-family: var(--font-mono);
  font-size: clamp(.92rem, 2vw, 1.08rem);
  font-weight: 600;
  letter-spacing: .02em;
  color: var(--text);
  margin-bottom: 18px;
}
.prh-hero-overview {
  color: var(--muted);
  font-size: clamp(.98rem, 2vw, 1.08rem);
  line-height: 1.75;
  max-width: 70ch;
  margin-bottom: 26px;
}
.prh-hero-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 30px; }
.prh-tag {
  font-family: var(--font-mono);
  font-size: .72rem; font-weight: 700; letter-spacing: .04em;
  color: var(--text); background: var(--surface-2);
  border: 1px solid var(--border-strong); padding: 7px 12px;
}

/* ---- Featured image ------------------------------------ */
.prh-figure { margin: 0; }
.prh-featured {
  position: relative;
  border: 1px solid var(--border-strong);
  background:
    linear-gradient(180deg, var(--primary-dim), transparent 55%),
    repeating-linear-gradient(0deg, transparent 0 26px, rgba(255,255,255,.018) 26px 27px),
    repeating-linear-gradient(90deg, transparent 0 26px, rgba(255,255,255,.018) 26px 27px),
    var(--surface);
  aspect-ratio: 16 / 9;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  overflow: hidden;
  text-align: center;
  padding: 24px;
}
.prh-featured img { width: 100%; height: 100%; object-fit: cover; position: absolute; inset: 0; }
.prh-featured::before,
.prh-featured::after {
  content: "";
  position: absolute;
  width: 26px; height: 26px;
  border: 2px solid var(--primary-line);
}
.prh-featured::before { top: 14px; left: 14px; border-right: none; border-bottom: none; }
.prh-featured::after { bottom: 14px; right: 14px; border-left: none; border-top: none; }
.prh-featured-icon { font-size: 2.4rem; color: var(--primary); line-height: 1; }
.prh-featured-label {
  font-family: var(--font-mono);
  font-size: .72rem; font-weight: 700; letter-spacing: .12em;
  text-transform: uppercase; color: var(--muted);
}
.prh-figure figcaption {
  font-family: var(--font-mono);
  font-size: .7rem; color: var(--subtle);
  letter-spacing: .04em; margin-top: 10px;
  text-transform: uppercase;
}

/* ---- Section scaffolding ------------------------------- */
.prh-section { padding: clamp(34px, 5vw, 52px) 0; border-top: 1px solid var(--border); }
.prh-section-head { margin-bottom: 24px; position: relative; padding-bottom: 14px; border-bottom: 1px solid var(--border); }
.prh-section-head::before {
  content: ""; position: absolute; left: 0; bottom: -1px;
  width: 56px; height: 2px; background: var(--primary);
}
.prh-kicker {
  display: block;
  font-family: var(--font-mono);
  font-size: .68rem; font-weight: 700; letter-spacing: .1em;
  text-transform: uppercase; color: var(--primary); margin-bottom: 8px;
}
.prh-section-head h2 {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3vw, 1.95rem); font-weight: 800;
  letter-spacing: -.02em; text-transform: uppercase; line-height: 1;
}
.prh-prose { color: var(--muted); font-size: 1rem; line-height: 1.8; max-width: 72ch; }
.prh-prose + .prh-prose { margin-top: 16px; }
.prh-prose strong { color: var(--text); font-weight: 700; }

/* ---- Objectives grid ----------------------------------- */
.prh-obj-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(260px, 100%), 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
}
.prh-obj {
  background: var(--surface);
  padding: 20px 22px;
  display: flex;
  gap: 14px;
  align-items: flex-start;
  transition: background var(--t);
}
.prh-obj:hover { background: var(--surface-hover); }
.prh-obj-num {
  font-family: var(--font-mono);
  font-size: .78rem; font-weight: 800; color: var(--primary);
  border: 1px solid var(--primary-line); background: var(--primary-soft);
  width: 30px; height: 30px; flex: 0 0 30px;
  display: flex; align-items: center; justify-content: center;
}
.prh-obj p { font-size: .92rem; line-height: 1.6; color: var(--text); }

/* ---- Challenge cards ----------------------------------- */
.prh-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(290px, 100%), 1fr));
  gap: 16px;
}
.prh-card {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: border-color var(--t), background var(--t);
}
.prh-card:hover { border-color: var(--primary-line); background: var(--surface-hover); }
.prh-card-tag {
  font-family: var(--font-mono);
  font-size: .66rem; font-weight: 700; letter-spacing: .08em;
  text-transform: uppercase; color: var(--primary);
}
.prh-card h3 { font-size: 1.05rem; font-weight: 800; line-height: 1.25; letter-spacing: -.01em; }
.prh-card p { font-size: .9rem; color: var(--muted); line-height: 1.7; }
.prh-card ul { display: flex; flex-direction: column; gap: 7px; margin-top: 2px; }
.prh-card ul li {
  font-size: .88rem; color: var(--subtle); line-height: 1.5;
  padding-left: 16px; position: relative;
}
.prh-card ul li::before { content: "\2192"; color: var(--primary); position: absolute; left: 0; }

/* ---- Callout ------------------------------------------- */
.prh-callout {
  border: 1px solid var(--border-strong);
  border-left: 3px solid var(--primary);
  background:
    linear-gradient(180deg, var(--primary-dim), transparent 70%),
    var(--surface);
  padding: 22px 24px;
  margin-top: 22px;
}
.prh-callout-label {
  font-family: var(--font-mono);
  font-size: .68rem; font-weight: 700; letter-spacing: .08em;
  text-transform: uppercase; color: var(--primary); margin-bottom: 8px;
  display: block;
}
.prh-callout p { color: var(--text); font-size: .96rem; line-height: 1.7; }

/* ---- Equipment cards ----------------------------------- */
.prh-equip-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(200px, 100%), 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  margin-top: 22px;
}
.prh-equip {
  background: var(--surface-2);
  padding: 16px 18px;
  display: flex;
  gap: 12px;
  align-items: center;
  transition: background var(--t);
}
.prh-equip:hover { background: var(--surface-hover); }
.prh-equip-icon {
  font-size: 1.05rem; color: var(--primary);
  width: 24px; flex: 0 0 24px; text-align: center;
}
.prh-equip-name { font-size: .9rem; font-weight: 700; color: var(--text); line-height: 1.35; }

/* ---- Considerations (two-column define list) ----------- */
.prh-consider {
  display: grid;
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
}
.prh-consider-row {
  background: var(--surface);
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 20px;
  padding: 22px 24px;
}
.prh-consider-row:hover { background: var(--surface-hover); }
.prh-consider-term {
  font-family: var(--font-display);
  font-size: 1.05rem; font-weight: 800; letter-spacing: -.01em;
  color: var(--text);
}
.prh-consider-term small {
  display: block; margin-top: 6px;
  font-family: var(--font-mono); font-size: .66rem; font-weight: 700;
  letter-spacing: .08em; text-transform: uppercase; color: var(--primary);
}
.prh-consider-body p { color: var(--muted); font-size: .94rem; line-height: 1.7; margin-bottom: 12px; }
.prh-chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.prh-chip {
  font-family: var(--font-mono);
  font-size: .72rem; font-weight: 600; letter-spacing: .03em;
  color: var(--text); background: var(--surface-2);
  border: 1px solid var(--border-strong); padding: 7px 12px;
}
.prh-chip::before { content: "// "; color: var(--primary); }

/* ---- Lessons timeline ---------------------------------- */
.prh-timeline { position: relative; margin-top: 8px; padding-left: 28px; }
.prh-timeline::before {
  content: ""; position: absolute; left: 6px; top: 6px; bottom: 6px;
  width: 1px; background: var(--border-strong);
}
.prh-tl-item { position: relative; padding: 0 0 26px 0; }
.prh-tl-item:last-child { padding-bottom: 0; }
.prh-tl-item::before {
  content: ""; position: absolute; left: -28px; top: 4px;
  width: 13px; height: 13px;
  background: var(--bg); border: 2px solid var(--primary);
}
.prh-tl-item h3 {
  font-size: 1rem; font-weight: 800; letter-spacing: -.01em;
  margin-bottom: 6px; color: var(--text);
}
.prh-tl-item p { color: var(--muted); font-size: .92rem; line-height: 1.7; max-width: 64ch; }

/* ---- Contribution list --------------------------------- */
.prh-contrib {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(300px, 100%), 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
}
.prh-contrib li {
  background: var(--surface);
  padding: 18px 20px;
  display: flex; gap: 12px; align-items: flex-start;
  font-size: .94rem; line-height: 1.6; color: var(--text);
  transition: background var(--t);
}
.prh-contrib li:hover { background: var(--surface-hover); }
.prh-contrib li::before {
  content: "\2713";
  color: var(--primary); font-weight: 800; flex: 0 0 auto;
  font-family: var(--font-mono);
}

/* ---- Expandable technical details ---------------------- */
.prh-details {
  border: 1px solid var(--border);
  background: var(--surface);
  margin-top: 14px;
}
.prh-details + .prh-details { margin-top: -1px; }
.prh-details summary {
  list-style: none;
  cursor: pointer;
  padding: 18px 22px;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  font-weight: 700; font-size: .98rem; color: var(--text);
  transition: color var(--t);
}
.prh-details summary::-webkit-details-marker { display: none; }
.prh-details summary:hover { color: var(--primary); }
.prh-details summary .prh-details-icon {
  font-family: var(--font-mono); color: var(--primary);
  font-size: 1.1rem; transition: transform var(--t-med); flex: 0 0 auto;
}
.prh-details[open] summary .prh-details-icon { transform: rotate(45deg); }
.prh-details-body { padding: 0 22px 20px; }
.prh-details-body p { color: var(--muted); font-size: .92rem; line-height: 1.75; }
.prh-details-body ul { margin-top: 10px; display: flex; flex-direction: column; gap: 7px; }
.prh-details-body ul li {
  font-size: .9rem; color: var(--subtle); line-height: 1.55;
  padding-left: 16px; position: relative;
}
.prh-details-body ul li::before { content: "\2192"; color: var(--primary); position: absolute; left: 0; }

/* ---- Gallery ------------------------------------------- */
.prh-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(240px, 100%), 1fr));
  gap: 12px;
  margin-top: 8px;
}
.prh-gallery-item {
  position: relative;
  border: 1px solid var(--border-strong);
  background:
    repeating-linear-gradient(0deg, transparent 0 22px, rgba(255,255,255,.018) 22px 23px),
    repeating-linear-gradient(90deg, transparent 0 22px, rgba(255,255,255,.018) 22px 23px),
    var(--surface);
  aspect-ratio: 4 / 3;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 8px; text-align: center; padding: 16px;
  overflow: hidden;
}
.prh-gallery-item img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.prh-gallery-item .prh-gallery-icon { font-size: 1.4rem; color: var(--primary-line); }
.prh-gallery-item .prh-gallery-cap {
  font-family: var(--font-mono); font-size: .66rem; font-weight: 700;
  letter-spacing: .06em; text-transform: uppercase; color: var(--subtle);
}

/* ---- Next/CTA ------------------------------------------ */
.prh-consult {
  border: 1px solid var(--border-strong);
  background:
    linear-gradient(180deg, var(--primary-dim), transparent 60%),
    var(--surface);
  padding: clamp(28px, 5vw, 44px);
  margin-top: 8px;
}
.prh-consult h2 {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3.2vw, 2rem); font-weight: 800;
  letter-spacing: -.02em; line-height: 1.1; margin-bottom: 12px; max-width: 24ch;
}
.prh-consult-lead { color: var(--muted); line-height: 1.75; font-size: 1rem; max-width: 64ch; margin-bottom: 24px; }
.prh-consult-row { display: flex; align-items: center; gap: 18px; flex-wrap: wrap; }
.prh-consult-note { font-family: var(--font-mono); font-size: .72rem; color: var(--muted); letter-spacing: .03em; }

/* ---- Related ------------------------------------------- */
.prh-related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(220px, 100%), 1fr));
  gap: 12px;
}
.prh-related-card {
  display: flex; flex-direction: column; gap: 4px;
  background: var(--surface); border: 1px solid var(--border);
  padding: 16px 18px; transition: border-color var(--t);
}
.prh-related-card:hover { border-color: var(--primary); }
.prh-related-cat {
  font-family: var(--font-mono); font-size: .66rem; font-weight: 700;
  letter-spacing: .05em; text-transform: uppercase; color: var(--muted);
}
.prh-related-name { font-size: .92rem; font-weight: 700; color: var(--text); }

/* ---- Reveal-on-scroll (page-local, mirrors site curve) - */
.prh-reveal { opacity: 1; transform: none; }

/* ---- Responsive ---------------------------------------- */
@media (max-width: 720px) {
  .prh-consider-row { grid-template-columns: 1fr; gap: 10px; }
}
@media (max-width: 560px) {
  .prh-consult-row { flex-direction: column; align-items: stretch; }
  .prh-consult-row .btn { width: 100%; }
  .prh-featured { aspect-ratio: 4 / 3; }
}