/* ==========================================================================
   SCROLLYTELLING ENGINE & STICKY CANVAS STYLES
   Full-Viewport Cinematic Knee Visualization & Scroll Progression
   ========================================================================== */

/* The Scroll Track: Creates the 480vh scroll space for smooth continuous scrubbing */
.scrolly-section {
  position: relative;
  width: 100%;
  height: 480vh;
  background-color: var(--bg-primary);
  margin-top: 0;
}

/* Sticky Viewport Container: Pinned 100vw x 100vh throughout the 480vh track */
.scrolly-sticky-viewport {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-primary);
  z-index: 10;
}

/* Canvas Element: Hardware-accelerated image sequence renderer */
.scrolly-canvas {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 100%;
  height: 100%;
  object-fit: contain;
  pointer-events: none;
  z-index: 1;
}

/* Seamless Blending Vignette Overlay:
   Eliminates any potential border seams and blends the 1920x1080 canvas into #050505 perfectly */
.canvas-vignette-overlay {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(
    ellipse 85% 75% at 50% 50%,
    transparent 42%,
    rgba(5, 5, 5, 0.45) 75%,
    var(--bg-primary) 98%
  );
  z-index: 2;
}

/* Top and Bottom Linear Blend Gradients */
.canvas-edge-fade-top {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 140px;
  background: linear-gradient(180deg, var(--bg-primary) 0%, transparent 100%);
  pointer-events: none;
  z-index: 3;
}

.canvas-edge-fade-bottom {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 160px;
  background: linear-gradient(0deg, var(--bg-primary) 0%, transparent 100%);
  pointer-events: none;
  z-index: 3;
}

/* Simple Dark Overlay to darken background behind Hero text */
.hero-dark-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.65);
  pointer-events: none;
  z-index: 2;
  transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  opacity: 1;
}

.scrolly-sticky-viewport.scrolled-past-hero .hero-dark-overlay {
  opacity: 0;
}

/* Stage Overlay Container */
.scrolly-narrative-container {
  position: absolute;
  inset: 0;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 2rem;
  pointer-events: none;
  z-index: 15;
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: 1fr;
  align-items: center;
}

/* Narrative Stage Cards */
.stage-card {
  grid-area: 1 / 1;
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transform: translateY(28px) scale(0.98);
  filter: blur(8px);
  transition:
    opacity 0.45s cubic-bezier(0.16, 1, 0.3, 1),
    transform 0.45s cubic-bezier(0.16, 1, 0.3, 1),
    filter 0.45s cubic-bezier(0.16, 1, 0.3, 1),
    visibility 0.45s;
  max-width: 540px;
}

.stage-card.active {
  pointer-events: auto;
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
  filter: blur(0px);
}

/* Stage Specific Alignments */

/* Stage 1: Hero Centered (Original Clean Floating Layout) */
.stage-card.stage-hero {
  max-width: 820px;
  margin: 0 auto;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stage-card.stage-hero .btn-group {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  flex-wrap: wrap;
  justify-content: center;
}

.stage-card.stage-hero .trust-tag {
  margin-top: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Stage 2: Understanding Knee Anatomy (Left Aligned) */
.stage-card.stage-left {
  justify-self: start;
  text-align: left;
  background: var(--bg-surface-glass);
  padding: 2.25rem 2.5rem;
  border-radius: 24px;
  border: 1px solid var(--border-subtle);
  backdrop-filter: blur(28px) saturate(180%);
  -webkit-backdrop-filter: blur(28px) saturate(180%);
  box-shadow: var(--shadow-elevation);
}

/* Stage 3: Hyaluronic Acid (Right Aligned) */
.stage-card.stage-right {
  justify-self: end;
  text-align: left;
  background: var(--bg-surface-glass);
  padding: 2.25rem 2.5rem;
  border-radius: 24px;
  border: 1px solid var(--border-subtle);
  backdrop-filter: blur(28px) saturate(180%);
  -webkit-backdrop-filter: blur(28px) saturate(180%);
  box-shadow: var(--shadow-elevation);
}

/* Stage 4: Precision Injection (Left Aligned) */
.stage-card.stage-left-clean {
  justify-self: start;
  text-align: left;
  background: rgba(10, 11, 14, 0.78);
  padding: 2.25rem 2.5rem;
  border-radius: 24px;
  border: 1px solid rgba(70, 199, 232, 0.22);
  backdrop-filter: blur(28px);
  box-shadow: 0 16px 40px -10px rgba(0, 0, 0, 0.8), 0 0 30px -5px var(--accent-cyan-glow);
}

/* Stage 5: Inside the Joint (Right Aligned Minimalist) */
.stage-card.stage-right-minimal {
  justify-self: end;
  text-align: left;
  background: var(--bg-surface-glass);
  padding: 2.25rem 2.5rem;
  border-radius: 24px;
  border: 1px solid var(--border-subtle);
  backdrop-filter: blur(28px);
  box-shadow: var(--shadow-elevation);
}

/* Stage 6: Final Call to Action (Centered Editorial) */
.stage-card.stage-final {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
  background: rgba(10, 11, 14, 0.82);
  padding: 3rem 3.5rem;
  border-radius: 28px;
  border: 1px solid rgba(70, 199, 232, 0.28);
  backdrop-filter: blur(32px);
  box-shadow: 0 24px 60px -12px rgba(0, 0, 0, 0.9), 0 0 50px -10px var(--accent-cyan-glow);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stage-card.stage-final .btn-group {
  display: flex;
  gap: 1.25rem;
  margin-top: 2rem;
  flex-wrap: wrap;
  justify-content: center;
}

/* Anatomical Feature Tags List */
.anatomical-tags-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.25rem;
}

.anatomical-tag {
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.anatomical-tag.accent {
  border-color: rgba(70, 199, 232, 0.35);
  color: var(--accent-cyan-light);
  background: rgba(70, 199, 232, 0.08);
}

/* Scrollytelling Stage Indicator Rail (Apple-style scrub dots on desktop right) */
.scrolly-progress-rail {
  position: absolute;
  right: 2.5rem;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
  z-index: 25;
  pointer-events: auto;
}

.rail-dot {
  position: relative;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.22);
  transition: all var(--transition-smooth);
  cursor: pointer;
  border: none;
  padding: 0;
}

.rail-dot::after {
  content: attr(data-label);
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%) translateX(6px);
  opacity: 0;
  pointer-events: none;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  white-space: nowrap;
  transition: all var(--transition-fast);
  background: rgba(5, 5, 5, 0.85);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
}

.rail-dot:hover::after {
  opacity: 1;
  transform: translateY(-50%) translateX(0);
}

.rail-dot.active {
  width: 10px;
  height: 24px;
  border-radius: 9999px;
  background: var(--accent-cyan);
  box-shadow: 0 0 16px var(--accent-cyan);
}

/* Scroll Prompt Indicator at Bottom of Hero */
.scroll-prompt {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.65rem;
  z-index: 20;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.scroll-mouse-wheel {
  width: 20px;
  height: 32px;
  border: 1.5px solid rgba(255, 255, 255, 0.25);
  border-radius: 12px;
  display: flex;
  justify-content: center;
  padding-top: 6px;
}

.scroll-wheel-dot {
  width: 3px;
  height: 6px;
  border-radius: 2px;
  background-color: var(--accent-cyan);
  animation: scrollMouseAnimation 1.8s cubic-bezier(0.65, 0, 0.35, 1) infinite;
}

@keyframes scrollMouseAnimation {
  0% { transform: translateY(0); opacity: 1; }
  60% { transform: translateY(10px); opacity: 0; }
  100% { transform: translateY(0); opacity: 0; }
}

/* Experience Preloader */
.canvas-preloader {
  position: fixed;
  inset: 0;
  background: var(--bg-primary);
  z-index: 999;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.6s;
}

.canvas-preloader.loaded {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.preloader-brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
}

.preloader-logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: #ffffff;
}

.preloader-sub {
  font-size: 0.8rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-cyan);
}

.preloader-bar-wrap {
  width: 240px;
  height: 3px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 9999px;
  overflow: hidden;
  position: relative;
}

.preloader-bar {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--accent-cyan) 0%, var(--accent-cyan-light) 100%);
  box-shadow: 0 0 12px var(--accent-cyan);
  transition: width 0.1s linear;
}

.preloader-text {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}