/* ═══════════════════════════════════════════
   WHY KOREA — Text Mask Reveal + Sticky Stack
   ═══════════════════════════════════════════ */

/* ── Text Mask Reveal ── */
.mask-section {
  position: relative;
  min-height: 350vh;
}

.mask-section__eyebrow {
  position: absolute;
  top: 15%;
  left: 50%;
  transform: translateX(-50%);
  z-index: 10;
  white-space: nowrap;
}

.mask-sticky {
  position: sticky;
  top: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.mask-video {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #06101a 0%, #0a1628 30%, #060a14 60%, #0f1629 100%);
  background-size: 400% 400%;
  animation: maskShiftBg 8s ease infinite;
  opacity: 0.8;
}

@keyframes maskShiftBg {
  0%   { background-position: 0% 50%; }
  50%  { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.mask-overlay {
  position: absolute;
  inset: 0;
  background: var(--color-bg-deep);
  display: flex;
  align-items: center;
  justify-content: center;
}

.mask-text {
  font-family: var(--font-display);
  font-size: clamp(40px, 10vw, 140px);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  line-height: 0.95;
  text-align: center;
  text-transform: uppercase;
  max-width: 90vw;
  background: var(--color-bg-deep);
  color: transparent;
  -webkit-text-stroke: 1.5px rgba(232, 236, 244, 0.12);
  position: relative;
  z-index: 2;
}

.mask-reveal {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 3;
  clip-path: inset(100% 0 0 0);
}

.mask-text-filled {
  font-family: var(--font-display);
  font-size: clamp(40px, 10vw, 140px);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  line-height: 0.95;
  text-align: center;
  text-transform: uppercase;
  max-width: 90vw;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-bright) 50%, #ffffff 100%);
  -webkit-background-clip: text;
}

.mask-subtext {
  position: absolute;
  bottom: 12%;
  left: 50%;
  transform: translateX(-50%);
  text-align: center;
  opacity: 0;
  z-index: 4;
}

.mask-subtext p {
  font-size: var(--text-body);
  color: var(--color-text-secondary);
  max-width: 70ch;
  line-height: var(--leading-body);
}

/* ── Sticky Card Stack ── */
.sticky-cards-section {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--section-padding-x) var(--section-gap);
}

.sticky-card {
  position: sticky;
  border-radius: var(--radius-xl);
  padding: var(--space-10) var(--space-8);
  margin-bottom: var(--space-8);
  min-height: 320px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
  transition: transform 0.1s ease;
  will-change: transform;
}

.sticky-card:nth-child(1) {
  top: 80px;
  background: linear-gradient(135deg, #0a1628, #141c35);
  border: 1px solid rgba(45, 122, 255, 0.15);
  z-index: 1;
}
.sticky-card:nth-child(2) {
  top: 100px;
  background: linear-gradient(135deg, #0f1629, #1a2440);
  border: 1px solid rgba(45, 122, 255, 0.12);
  z-index: 2;
}
.sticky-card:nth-child(3) {
  top: 120px;
  background: linear-gradient(135deg, #141c35, #0f1629);
  border: 1px solid rgba(45, 122, 255, 0.10);
  z-index: 3;
}
.sticky-card:nth-child(4) {
  top: 140px;
  background: linear-gradient(135deg, #0a0f1e, #0f1629);
  border: 1px solid rgba(45, 122, 255, 0.08);
  z-index: 4;
}

.sticky-card__num {
  font-family: var(--font-mono);
  font-size: var(--text-eyebrow);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-accent);
  opacity: 0.7;
  margin-bottom: var(--space-4);
}

.sticky-card__stat {
  font-family: var(--font-mono);
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  line-height: 1;
  margin-bottom: var(--space-2);
}

.sticky-card__stat-suffix {
  color: var(--color-accent);
  font-size: 0.5em;
}

.sticky-card__title {
  font-family: var(--font-display);
  font-size: var(--text-h3);
  font-weight: var(--weight-bold);
  margin-bottom: var(--space-3);
}

.sticky-card__desc {
  font-size: var(--text-body);
  color: var(--color-text-secondary);
  line-height: var(--leading-body);
  max-width: 50ch;
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .mask-text,
  .mask-text-filled {
    font-size: clamp(32px, 12vw, 60px);
  }
  .mask-section {
    min-height: 200vh;
  }

  .sticky-card {
    padding: var(--space-8) var(--space-6);
    min-height: 260px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .mask-video {
    animation: none;
  }
}