/* ── THEME OVERRIDE (light / warm) ── */
:root {
  --white-bg:      #ffffff;
  --light-grey:    #6b6b6b;
  --dark-grey:     #1f1f1f;
  --orange-accent: #c0622a;
  --rule:          #e0dcd8;
  --surface:       #f7f5f3;
  --card-bg:       #fdfcfb;
}

/* ── cs4 theme rules ── */
#cs4 {
  background-color: var(--white-bg);
  font-family: var(--sans);
  font-weight: 300;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
#cs4 p                     { color: var(--light-grey); }
#cs4 h1, #cs4 h2,
#cs4 h3, #cs4 h4           { color: var(--dark-grey); }
#cs4 span                  { color: var(--orange-accent); }
#cs4 .case-study-container {
  display: flex;
  flex-direction: column;
  gap: 60px;
}

/* ── CONTAINER ── */
.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 2rem 2rem 6rem;
}

/* ── BACK LINK ── */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--light-grey);
  text-decoration: none;
  margin-bottom: 2.5rem;
  transition: color 0.2s;
}
.back-link:hover { color: var(--dark-grey); }

/* ── HEADER ── */
.case-study-header {
  margin-bottom: 2.5rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--rule);
}
.case-study-header h1 {
  font-family: var(--serif);
  font-size: clamp(1.85rem, 4vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-bottom: 0.85rem;
}
.case-study-header .subtitle {
  font-size: 1.05rem;
  line-height: 1.7;
  max-width: 58ch;
  margin-bottom: 0;
}
.case-study-header .tags {
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  margin-bottom: 0.85rem;
  display: block;
}

/* ── META ROW ── */
.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  margin-top: 1.5rem;
}
.meta-label {
  font-size: 0.62rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--light-grey);
  opacity: 0.7;
  margin-bottom: 0.2rem;
}
.meta-value {
  font-size: 0.85rem;
  color: var(--dark-grey);
  font-weight: 400;
}

/* ── SECTION ── */
.case-study-section h2 {
  font-family: var(--serif);
  font-size: 1.45rem;
  font-weight: 400;
  margin-bottom: 0.85rem;
  line-height: 1.25;
}
.case-study-section p {
  font-size: 0.975rem;
  line-height: 1.75;
  margin-bottom: 0.9rem;
  max-width: 64ch;
}
.case-study-section p:last-child { margin-bottom: 0; }
.case-study-section p.wide      { max-width: none; }

/* ── COLUMNS ── */
.columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
  align-items: start;
}
.columns.three { grid-template-columns: 1fr 1fr 1fr; }

/* ── IMAGES ── */
.case-study-image {
  width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--rule);
}
.img-caption {
  font-size: 0.75rem;
  opacity: 0.75;
  font-style: italic;
  margin-top: 0.5rem;
  line-height: 1.5;
}

/* ── IMPACT BAR ── */
.impact-bar {
  background: var(--dark-grey);
  padding: 2rem 2.25rem;
}
.impact-bar-label {
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--orange-accent);
  font-weight: 500;
  margin-bottom: 1rem;
}
.impact-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}
.impact-list li {
  font-size: 0.9rem;
  line-height: 1.55;
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  color: #d8d0c8;
}
.impact-list li::before {
  content: '↳';
  color: var(--orange-accent);
  flex-shrink: 0;
  margin-top: 0.05em;
}

/* ── TENSION BLOCK ── */
.tension-block {
  background: var(--surface);
  border: 1px solid var(--rule);
  padding: 1.75rem 2rem;
  margin-top: 2rem;
}
.tension-label {
  font-size: 0.62rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--orange-accent);
  font-weight: 500;
  margin-bottom: 1.25rem;
}
.tension-cols {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1.5rem;
  align-items: center;
}
.t-label {
  font-size: 0.62rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--light-grey);
  opacity: 0.7;
  margin-bottom: 0.4rem;
}
.tension-side p {
  font-size: 0.875rem;
  color: var(--dark-grey);
  line-height: 1.55;
  margin: 0;
  max-width: none;
}
.tension-arrow {
  color: var(--orange-accent);
  font-size: 1.25rem;
  text-align: center;
}

/* ── METHOD BLOCK ── */
.method-block {
  border: 1px solid var(--rule);
  background: var(--card-bg);
  padding: 1.25rem 1.5rem;
  margin-top: 1.5rem;
}
.method-block-label {
  font-size: 0.62rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--light-grey);
  opacity: 0.65;
  margin-bottom: 0.6rem;
}
.method-block p {
  font-size: 0.82rem;
  margin: 0;
  max-width: none;
  line-height: 1.65;
}

/* ── CALLOUT ── */
.callout {
  border-left: 3px solid var(--orange-accent);
  padding: 1rem 1.5rem;
  background: #fdf7f3;
  margin-top: 1.5rem;
}
.callout p {
  margin: 0;
  font-size: 0.9rem;
  font-style: italic;
  color: var(--dark-grey);
  max-width: none;
}

/* ── INSIGHT GRID ── */
.insight-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  margin-top: 1.5rem;
}
.insight-card            { background: var(--card-bg); padding: 1.5rem 1.75rem; }
.insight-card.full       { grid-column: 1 / -1; }
.insight-num {
  font-family: var(--serif);
  font-size: 1.75rem;
  color: var(--orange-accent);
  line-height: 1;
  margin-bottom: 0.5rem;
  opacity: 0.5;
}
.insight-job {
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--orange-accent);
  margin-bottom: 0.5rem;
}
.insight-title {
  font-size: 0.875rem;
  color: var(--dark-grey);
  font-weight: 500;
  line-height: 1.4;
  margin-bottom: 0.6rem;
}
.insight-body {
  font-size: 0.78rem;
  line-height: 1.65;
  max-width: none;
  margin: 0 0 0.6rem;
}
.insight-body:last-of-type { margin-bottom: 0; }
.insight-quote {
  font-size: 0.78rem;
  font-style: italic;
  color: var(--dark-grey);
  line-height: 1.55;
  border-left: 2px solid var(--orange-accent);
  padding-left: 0.75rem;
  margin: 0.75rem 0;
}
.insight-shift {
  display: block;
  margin-top: 0.85rem;
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--orange-accent);
}
.insight-shift::before { content: '→ Product implication: '; }

/* ── IMPACT GRID ── */
.impact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  margin-top: 1.5rem;
}
.impact-cell   { background: var(--card-bg); padding: 1.5rem 1.75rem; }
.impact-num {
  font-family: var(--serif);
  font-size: 2rem;
  color: var(--orange-accent);
  line-height: 1;
  margin-bottom: 0.5rem;
  opacity: 0.45;
}
.impact-title {
  font-size: 0.875rem;
  color: var(--dark-grey);
  font-weight: 500;
  line-height: 1.4;
  margin-bottom: 0.5rem;
}
.impact-body {
  font-size: 0.78rem;
  line-height: 1.65;
  margin: 0;
}

/* ── FOOTER ── */
footer {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--rule);
  font-size: 0.75rem;
  text-align: center;
}

/* ── RESPONSIVE ── */
@media (max-width: 640px) {
  .columns, .columns.three,
  .insight-grid, .impact-grid { grid-template-columns: 1fr; }
  .insight-card.full           { grid-column: 1; }
  .tension-cols                { grid-template-columns: 1fr; }
  .tension-arrow               { display: none; }
}