/* =========================================
   CASE STUDY — case-study.css
   ========================================= */

/* ── INDEX PAGE ──────────────────────────── */

.cs-index-hero {
  padding:       80px 48px 64px;
  border-bottom: 1px solid var(--border);
}

.cs-kicker {
  display:        flex;
  align-items:    center;
  gap:            10px;
  font-size:      11px;
  color:          var(--blue);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin-bottom:  20px;
}

.cs-kicker::before {
  content:       "";
  width:         20px;
  height:        1.5px;
  background:    var(--blue);
  border-radius: 2px;
}

.cs-index-title {
  font-size:      clamp(3rem, 5.2vw, 5.6rem);
  line-height:    0.96;
  letter-spacing: -0.07em;
  font-weight:    300;
  color:          var(--text-primary);
  margin-bottom:  20px;
  max-width:      14ch;
}

.cs-index-title span { color: var(--blue); }

.cs-index-desc {
  font-size:   16px;
  line-height: 1.75;
  color:       var(--text-secondary);
  max-width:   52ch;
}

/* ── FILTER BAR ──────────────────────────── */

.cs-filter-bar {
  padding:     24px 48px;
  display:     flex;
  align-items: center;
  gap:         8px;
  border-bottom: 1px solid var(--border);
  flex-wrap:   wrap;
}

.cs-filter-btn {
  padding:         8px 16px;
  border:          1.5px solid var(--border);
  border-radius:   var(--radius-pill);
  background:      transparent;
  font-size:       12px;
  font-weight:     500;
  letter-spacing:  0.04em;
  color:           var(--text-muted);
  cursor:          pointer;
  font-family:     var(--font-primary);
  transition:
    border-color var(--t-fast) ease,
    color        var(--t-fast) ease,
    background   var(--t-fast) ease;
}

.cs-filter-btn:hover,
.cs-filter-btn.is-active {
  border-color: var(--blue);
  color:        var(--blue);
  background:   rgba(26,70,201,0.05);
}

/* ── CASE STUDY GRID ─────────────────────── */

.cs-grid {
  padding: 48px 48px 96px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap:     24px;
}

/* Featured card — spans 2 cols */
.cs-card--featured {
  grid-column: span 2;
}

/* ── CARD ────────────────────────────────── */

.cs-card {
  position:       relative;
  border-radius:  var(--radius-lg);
  overflow:       hidden;
  background:     #ffffff;
  border:         1px solid var(--border);
  display:        flex;
  flex-direction: column;
  cursor:         pointer;
  transition:
    transform   0.4s var(--ease-out),
    box-shadow  0.4s ease,
    border-color 0.3s ease;
  text-decoration: none;
  color:           inherit;
}

.cs-card:hover {
  transform:    translateY(-5px);
  box-shadow:   0 20px 60px rgba(26,70,201,0.10);
  border-color: rgba(26,70,201,0.18);
}

/* ── CARD IMAGE ──────────────────────────── */

.cs-card__image-wrap {
  position:    relative;
  overflow:    hidden;
  aspect-ratio: 16/9;
}

.cs-card--featured .cs-card__image-wrap {
  aspect-ratio: 21/9;
}

.cs-card__image {
  width:      100%;
  height:     100%;
  object-fit: cover;
  display:    block;
  transition: transform 0.7s var(--ease-out);
}

.cs-card:hover .cs-card__image {
  transform: scale(1.04);
}

.cs-card__overlay {
  position:   absolute;
  inset:      0;
  background: linear-gradient(to top, rgba(0,0,0,0.40) 0%, transparent 60%);
}

.cs-card__year {
  position:       absolute;
  top:            16px;
  right:          16px;
  padding:        5px 10px;
  background:     rgba(255,255,255,0.18);
  backdrop-filter: blur(8px);
  border-radius:  var(--radius-pill);
  font-size:      11px;
  font-weight:    500;
  color:          #ffffff;
  letter-spacing: 0.04em;
}

/* ── CARD BODY ───────────────────────────── */

.cs-card__body {
  padding:        24px;
  flex:           1;
  display:        flex;
  flex-direction: column;
  gap:            10px;
}

.cs-card__category {
  font-size:      10px;
  font-weight:    600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color:          var(--blue);
  opacity:        0.8;
}

.cs-card__title {
  font-size:      clamp(1.1rem, 1.8vw, 1.5rem);
  font-weight:    400;
  letter-spacing: -0.03em;
  line-height:    1.2;
  color:          var(--text-primary);
  transition:     color var(--t-fast) ease;
}

.cs-card:hover .cs-card__title { color: var(--blue); }

.cs-card__tagline {
  font-size:   14px;
  line-height: 1.6;
  color:       var(--text-muted);
}

.cs-card__tags {
  display:   flex;
  flex-wrap: wrap;
  gap:       6px;
  margin-top: auto;
  padding-top: 8px;
}

.cs-card__tag {
  padding:        4px 10px;
  background:     var(--bg);
  border:         1px solid var(--border);
  border-radius:  var(--radius-pill);
  font-size:      11px;
  color:          var(--text-muted);
}

/* ── CARD METRICS ────────────────────────── */

.cs-card__metrics {
  display:       grid;
  grid-template-columns: repeat(4, 1fr);
  border-top:    1px solid var(--border);
  margin-top:    auto;
}

.cs-card__metric {
  padding:       14px 16px;
  text-align:    center;
  transition:    background var(--t-fast) ease;
}

.cs-card__metric:not(:last-child) { border-right: 1px solid var(--border); }
.cs-card:hover .cs-card__metric   { background: rgba(26,70,201,0.02); }

.cs-card__metric-value {
  display:        block;
  font-size:      1.1rem;
  font-weight:    700;
  letter-spacing: -0.03em;
  color:          var(--blue);
  line-height:    1;
  margin-bottom:  3px;
}

.cs-card__metric-label {
  font-size: 10px;
  color:     var(--text-muted);
  line-height: 1.3;
}

/* ── CASE STUDY DETAIL PAGE ──────────────── */

/* PROGRESS BAR */
/* ── READING PROGRESS CIRCLE ─────────────── */

.cs-progress-circle {
  position:   fixed;
  bottom:     32px;
  right:      32px;
  z-index:    200;
  width:      48px;
  height:     48px;
  cursor:     pointer;

  opacity:    0;
  transform:  translateY(12px) scale(0.9);
  transition:
    opacity   0.4s var(--ease-out),
    transform 0.4s var(--ease-out);
}

.cs-progress-circle.is-visible {
  opacity:   1;
  transform: translateY(0) scale(1);
}

/* SVG ring */
.cs-progress-circle svg {
  width:    48px;
  height:   48px;
  transform: rotate(-90deg); /* start from top */
}

.cs-progress-circle__track {
  fill:         none;
  stroke:       rgba(26,70,201,0.12);
  stroke-width: 3;
}

.cs-progress-circle__fill {
  fill:             none;
  stroke:           var(--blue);
  stroke-width:     3;
  stroke-linecap:   round;
  stroke-dasharray: 126; /* 2π × 20 */
  stroke-dashoffset: 126;
  transition:       stroke-dashoffset 0.15s linear;
}

/* Inner button */
.cs-progress-circle__btn {
  position:        absolute;
  inset:           6px;
  border-radius:   50%;
  background:      rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border:          1px solid rgba(26,70,201,0.10);
  display:         flex;
  align-items:     center;
  justify-content: center;
  box-shadow:      0 4px 16px rgba(0,0,0,0.10);
  transition:
    background   var(--t-fast) ease,
    box-shadow   var(--t-fast) ease,
    transform    var(--t-fast) ease;
}

.cs-progress-circle:hover .cs-progress-circle__btn {
  background:  rgba(26,70,201,0.06);
  box-shadow:  0 6px 24px rgba(26,70,201,0.18);
  transform:   scale(1.05);
}

/* Percentage text */
.cs-progress-circle__pct {
  font-size:   10px;
  font-weight: 600;
  color:       var(--blue);
  line-height: 1;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

/* Mobile — smaller, lower position */
@media (max-width: 768px) {

  .cs-progress-circle {
    bottom: 20px;
    right:  16px;
    width:  40px;
    height: 40px;
  }

  .cs-progress-circle svg {
    width:  40px;
    height: 40px;
  }

  .cs-progress-circle__fill {
    stroke-dasharray: 100;  /* 2π × 16 */
    stroke-dashoffset: 100;
  }

  .cs-progress-circle__track { r: 16; }
  .cs-progress-circle__fill  { r: 16; }
  .cs-progress-circle__btn   { inset: 5px; }
  .cs-progress-circle__pct   { font-size: 9px; }

}

@media (prefers-reduced-motion: reduce) {
  .cs-progress-circle          { transition: none; }
  .cs-progress-circle__fill    { transition: none; }
  .cs-progress-circle__btn     { transition: none; }
}

/* HERO */
.cs-detail-hero {
  position:    relative;
  height:      60vh;
  min-height:  480px;
  max-height:  640px;
  overflow:    hidden;
}

.cs-detail-hero__img {
  width:      100%;
  height:     100%;
  object-fit: cover;
  display:    block;
}

.cs-detail-hero__overlay {
  position:   absolute;
  inset:      0;
  background: linear-gradient(
    to bottom,
    rgba(0,0,0,0.20) 0%,
    rgba(0,0,0,0.65) 100%
  );
}

.cs-detail-hero__content {
  position:  absolute;
  bottom:    48px;
  left:      48px;
  right:     48px;
  color:     #ffffff;
  z-index:   2;
}

.cs-detail-hero__category {
  font-size:      11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  opacity:        0.75;
  margin-bottom:  12px;
}

.cs-detail-hero__title {
  font-size:      clamp(2.2rem, 4.5vw, 4.4rem);
  font-weight:    300;
  letter-spacing: -0.06em;
  line-height:    0.96;
  margin-bottom:  16px;
}

.cs-detail-hero__tagline {
  font-size:   17px;
  line-height: 1.5;
  color:       rgba(255,255,255,0.82);
  max-width:   60ch;
}

/* META BAR */
.cs-meta-bar {
  display:               grid;
  grid-template-columns: repeat(4,1fr);
  border-bottom:         1px solid var(--border);
  background:            rgba(255,255,255,0.70);
  backdrop-filter:       blur(12px);
}

.cs-meta-item {
  padding: 20px 28px;
}

.cs-meta-item:not(:last-child) { border-right: 1px solid var(--border); }

.cs-meta-item__label {
  font-size:      10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color:          var(--text-muted);
  margin-bottom:  4px;
  display:        block;
}

.cs-meta-item__value {
  font-size:   14px;
  font-weight: 500;
  color:       var(--text-primary);
}

/* CONTENT LAYOUT */
.cs-content {
  display:               grid;
  grid-template-columns: 240px 1fr;
  gap:                   0;
  max-width:             1200px;
  margin:                0 auto;
  padding:               64px 48px;
  align-items:           start;
}

/* STICKY NAV */
.cs-nav {
  position: sticky;
  top:      100px;
}

.cs-nav__item {
  display:     block;
  font-size:   13px;
  color:       var(--text-muted);
  padding:     8px 0 8px 16px;
  border-left: 2px solid var(--border);
  margin-bottom: 2px;
  transition:
    color       var(--t-fast) ease,
    border-color var(--t-fast) ease;
  text-decoration: none;
}

.cs-nav__item:hover,
.cs-nav__item.is-active {
  color:        var(--blue);
  border-color: var(--blue);
}

/* ARTICLE */
.cs-article {
  max-width:  720px;
  display:    flex;
  flex-direction: column;
  gap:        64px;
}

.cs-section {
  scroll-margin-top: 100px;
}

.cs-section__label {
  font-size:      10px;
  font-weight:    600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color:          var(--blue);
  margin-bottom:  16px;
  display:        block;
}

.cs-section__title {
  font-size:      clamp(1.6rem, 2.8vw, 2.4rem);
  font-weight:    300;
  letter-spacing: -0.05em;
  color:          var(--text-primary);
  line-height:    1.05;
  margin-bottom:  20px;
}

.cs-section__body {
  font-size:   16px;
  line-height: 1.80;
  color:       var(--text-secondary);
}

.cs-section__body p + p { margin-top: 16px; }

.cs-section__body strong {
  font-weight: 600;
  color:       var(--text-primary);
}

/* CALLOUT */
.cs-callout {
  padding:       24px 28px;
  background:    rgba(26,70,201,0.04);
  border-left:   3px solid var(--blue);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size:     15px;
  line-height:   1.7;
  color:         var(--text-secondary);
  font-style:    italic;
  margin:        24px 0;
}

/* METRIC CARDS IN ARTICLE */
.cs-metrics-row {
  display:               grid;
  grid-template-columns: repeat(2, 1fr);
  gap:                   12px;
  margin:                24px 0;
}

.cs-metric-card {
  padding:       24px;
  background:    #ffffff;
  border:        1px solid var(--border);
  border-radius: var(--radius-md);
  transition:    border-color var(--t-fast) ease, background var(--t-fast) ease;
}

.cs-metric-card:hover {
  border-color: rgba(26,70,201,0.20);
  background:   rgba(26,70,201,0.02);
}

.cs-metric-card__value {
  font-size:      2.4rem;
  font-weight:    700;
  letter-spacing: -0.05em;
  color:          var(--blue);
  line-height:    1;
  margin-bottom:  6px;
}

.cs-metric-card__label {
  font-size:   13px;
  color:       var(--text-muted);
  line-height: 1.4;
}

/* PROCESS STEPS */
.cs-steps {
  display:        flex;
  flex-direction: column;
  gap:            0;
  margin:         24px 0;
}

.cs-step {
  display:       grid;
  grid-template-columns: 40px 1fr;
  gap:           20px;
  padding:       20px 0;
  border-bottom: 1px solid var(--border);
}

.cs-step:first-child { border-top: 1px solid var(--border); }

.cs-step__num {
  width:           36px;
  height:          36px;
  border-radius:   50%;
  background:      rgba(26,70,201,0.08);
  border:          1.5px solid rgba(26,70,201,0.18);
  display:         flex;
  align-items:     center;
  justify-content: center;
  font-size:       12px;
  font-weight:     600;
  color:           var(--blue);
  flex-shrink:     0;
}

.cs-step__title {
  font-size:   14px;
  font-weight: 600;
  color:       var(--text-primary);
  margin-bottom: 4px;
  line-height: 1.3;
}

.cs-step__desc {
  font-size:   14px;
  line-height: 1.65;
  color:       var(--text-muted);
}

/* INSIGHT TAG */
.cs-insight {
  display:        inline-flex;
  align-items:    center;
  gap:            8px;
  padding:        6px 14px;
  background:     rgba(26,70,201,0.08);
  border-radius:  var(--radius-pill);
  font-size:      12px;
  font-weight:    500;
  color:          var(--blue);
  margin:         4px 4px 4px 0;
}

/* NEXT CASE STUDY */
.cs-next {
  border-top:      1px solid var(--border);
  padding:         64px 48px;
  display:         grid;
  grid-template-columns: 1fr 1fr;
  gap:             48px;
  align-items:     center;
}

.cs-next__label {
  font-size:      11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color:          var(--text-muted);
  margin-bottom:  12px;
}

.cs-next__title {
  font-size:      clamp(1.6rem, 3vw, 2.8rem);
  font-weight:    300;
  letter-spacing: -0.05em;
  color:          var(--text-primary);
  margin-bottom:  20px;
  line-height:    1.05;
  transition:     color var(--t-fast) ease;
}

.cs-next__link:hover .cs-next__title { color: var(--blue); }

.cs-next__link {
  text-decoration: none;
  display:         block;
  padding:         32px;
  background:      #ffffff;
  border:          1px solid var(--border);
  border-radius:   var(--radius-lg);
  transition:
    transform    0.35s var(--ease-out),
    box-shadow   0.35s ease,
    border-color 0.3s ease;
}

.cs-next__link:hover {
  transform:    translateY(-4px);
  box-shadow:   0 16px 48px rgba(26,70,201,0.10);
  border-color: rgba(26,70,201,0.20);
}

.cs-next__arrow {
  font-size:  24px;
  color:      var(--blue);
  display:    block;
  margin-top: 8px;
  transition: transform var(--t-fast) ease;
}

.cs-next__link:hover .cs-next__arrow { transform: translate(4px,-4px); }

/* ── RESPONSIVE ──────────────────────────── */

@media (max-width: 1024px) {

  .cs-grid    { grid-template-columns: 1fr 1fr; padding: 40px; }
  .cs-card--featured { grid-column: span 2; }
  .cs-content { grid-template-columns: 1fr; padding: 48px 40px; }
  .cs-nav     { display: none; }
  .cs-filter-bar { padding: 20px 40px; }
  .cs-index-hero { padding: 64px 40px 52px; }

}

@media (max-width: 768px) {

  .cs-index-hero  { padding: 48px 20px 40px; }
  .cs-filter-bar  { padding: 16px 20px; gap: 6px; }
  .cs-grid        { grid-template-columns: 1fr; padding: 24px 20px 64px; gap: 16px; }
  .cs-card--featured { grid-column: span 1; }

  .cs-detail-hero__content { left: 20px; right: 20px; bottom: 28px; }
  .cs-detail-hero__title   { font-size: clamp(1.8rem, 8vw, 3rem); }

  .cs-meta-bar { grid-template-columns: 1fr 1fr; }
  .cs-meta-item:nth-child(2) { border-right: none; }
  .cs-meta-item:nth-child(3) { border-top: 1px solid var(--border); }
  .cs-meta-item:nth-child(4) { border-top: 1px solid var(--border); border-right: none; }

  .cs-content { padding: 40px 20px; }

  .cs-metrics-row  { grid-template-columns: 1fr 1fr; }
  .cs-card__metrics { grid-template-columns: 1fr 1fr; }
  .cs-card__metric:nth-child(2) { border-right: none; }
  .cs-card__metric:nth-child(3) { border-top: 1px solid var(--border); }
  .cs-card__metric:nth-child(4) { border-top: 1px solid var(--border); border-right: none; }

  .cs-next { grid-template-columns: 1fr; padding: 48px 20px; gap: 16px; }

}