/**
 * Intro CSS - Dark Premium Theme avec BEM
 * Animations GPU-friendly, accessibilité, responsive
 */

/* === Variables CSS === */
:root {
  --intro-bg-primary: rgba(15, 15, 25, 0.96);
  --intro-bg-secondary: rgba(5, 5, 15, 0.98);
  --intro-text-primary: #f8fafc;
  --intro-text-secondary: rgba(248, 250, 252, 0.8);
  --intro-accent-gold: #f59e0b;
  --intro-accent-red: #ef4444;
  --intro-accent-purple: #8b5cf6;
  --intro-accent-blue: #3b82f6;
  --intro-shadow-strong: 0 8px 25px rgba(0, 0, 0, 0.8);
  --intro-shadow-soft: 0 2px 20px rgba(0, 0, 0, 0.5);
  --intro-timing: cubic-bezier(0.22, 0.61, 0.36, 1);
  --intro-duration-fast: 0.3s;
  --intro-duration-medium: 0.6s;
  --intro-duration-slow: 0.9s;
}

/* === Base Overlay === */
.intro-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: radial-gradient(
    ellipse at center, 
    var(--intro-bg-primary) 0%, 
    var(--intro-bg-secondary) 100%
  );
  z-index: 9999;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  opacity: 1;
  backdrop-filter: blur(25px);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, 
               "Helvetica Neue", Arial, sans-serif;
  user-select: none;
  -webkit-user-select: none;
  isolation: isolate;
}

.intro-overlay[role="dialog"] {
  outline: none;
}

/* === Background Effects === */
.intro-overlay__background {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  background:
    radial-gradient(circle at 25% 25%, rgba(147, 51, 234, 0.12) 0%, transparent 60%),
    radial-gradient(circle at 75% 75%, rgba(245, 158, 11, 0.15) 0%, transparent 60%),
    radial-gradient(circle at 50% 20%, rgba(245, 158, 11, 0.18) 0%, transparent 70%),
    linear-gradient(135deg, rgba(0, 0, 0, 0.85) 0%, rgba(10, 10, 20, 0.95) 100%);
  backdrop-filter: blur(2px);
  will-change: transform;
}

.intro-overlay__background::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: 
    radial-gradient(circle at 1px 1px, rgba(255, 255, 255, 0.02) 1px, transparent 0);
  background-size: 20px 20px;
  opacity: 0.3;
  animation: grain 8s linear infinite;
}

/* === SVG Halo Effects === */
.intro-overlay__halo {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 120vw;
  height: 120vh;
  transform: translate(-50%, -50%) scale(0.8);
  opacity: 0;
  will-change: transform, opacity;
  z-index: 0;
  pointer-events: none;
}

/* === Skip Button === */
.intro-overlay__skip {
  position: absolute;
  top: clamp(1rem, 4vw, 2rem);
  right: clamp(1rem, 4vw, 2rem);
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--intro-text-secondary);
  padding: 0.75rem 1.5rem;
  border-radius: 2rem;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--intro-duration-fast) var(--intro-timing);
  backdrop-filter: blur(15px);
  opacity: 0;
  transform: translateY(-10px);
  z-index: 10;
  font-family: inherit;
  letter-spacing: 0.025em;
}

.intro-overlay__skip:hover,
.intro-overlay__skip:focus-visible {
  opacity: 1 !important;
  background: rgba(255, 255, 255, 0.15);
  border-color: rgba(255, 255, 255, 0.3);
  color: var(--intro-text-primary);
  transform: translateY(-12px);
  box-shadow: var(--intro-shadow-strong);
}

.intro-overlay__skip:focus-visible {
  outline: 2px solid var(--intro-accent-blue);
  outline-offset: 2px;
}

.intro-overlay__skip:active {
  transform: translateY(-8px);
}

/* === Content Container === */
.intro-overlay__content {
  position: relative;
  z-index: 5;
  max-width: min(90vw, 900px);
  padding: 2rem;
  text-align: center;
}

.intro-overlay__content:focus {
  outline: none;
}

/* === Phase Containers === */
.intro-overlay__phase {
  opacity: 0;
  transform: none; /* let GSAP control vertical movement to avoid final jump */
  will-change: transform, opacity;
  margin-bottom: 2rem;
  position: relative;
  text-align: center; /* ensure centered text in all phases */
}

.intro-overlay__phase:last-child {
  margin-bottom: 0;
}

.intro-overlay__phase[aria-hidden="true"] {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
}

/* === Text Styling === */
.intro-overlay__text {
  font-size: clamp(1.375rem, 4vw, 2.75rem);
  font-weight: 300;
  line-height: 1.4;
  color: var(--intro-text-primary);
  text-shadow: var(--intro-shadow-soft);
  margin: 0;
  letter-spacing: -0.025em;
  word-spacing: 0.1em;
}

.intro-overlay__text--highlight {
  background: linear-gradient(
    135deg, 
    var(--intro-accent-gold) 0%, 
    var(--intro-accent-red) 35%, 
    var(--intro-accent-purple) 100%
  );
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-size: 200% 200%;
  animation: gradientShift 6s ease-in-out infinite;
  font-weight: 500;
  position: relative;
}

.intro-overlay__text--highlight::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: inherit;
  filter: blur(2px);
  opacity: 0.5;
  z-index: -1;
}

/* === Animations === */
@keyframes grain {
  0%, 100% { transform: translate(0, 0); }
  10% { transform: translate(-5%, -5%); }
  20% { transform: translate(-10%, 5%); }
  30% { transform: translate(5%, -10%); }
  40% { transform: translate(-5%, 15%); }
  50% { transform: translate(-10%, 5%); }
  60% { transform: translate(15%, 0%); }
  70% { transform: translate(0%, 15%); }
  80% { transform: translate(-15%, 10%); }
  90% { transform: translate(10%, 5%); }
}

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

/* === Responsive Design === */
@media (max-width: 768px) {
  .intro-overlay__content {
    padding: 1.5rem 1rem;
  }
  
  .intro-overlay__skip {
    top: 1rem;
    right: 1rem;
    padding: 0.625rem 1.25rem;
    font-size: 0.8125rem;
  }
  
  .intro-overlay__text {
    line-height: 1.5;
    word-spacing: 0.05em;
  }
}

@media (max-width: 480px) {
  .intro-overlay__content {
    padding: 1rem 0.75rem;
  }
  
  .intro-overlay__phase {
    margin-bottom: 1.5rem;
  }
}

/* === Landscape Mobile === */
@media (max-height: 500px) and (orientation: landscape) {
  .intro-overlay__content {
    padding: 1rem;
  }
  
  .intro-overlay__skip {
    top: 0.75rem;
    right: 0.75rem;
    padding: 0.5rem 1rem;
    font-size: 0.75rem;
  }
}

/* === High Contrast Mode === */
@media (prefers-contrast: high) {
  .intro-overlay {
    background: #000;
  }
  
  .intro-overlay__background {
    background: #000;
  }
  
  .intro-overlay__text {
    color: #fff;
    text-shadow: none;
  }
  
  .intro-overlay__text--highlight {
    background: #fff;
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
  }
  
  .intro-overlay__skip {
    background: rgba(255, 255, 255, 0.2);
    border-color: #fff;
    color: #fff;
  }
}

/* === Reduced Motion === */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01s !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01s !important;
    transition-delay: 0s !important;
  }
  
  .intro-overlay__phase {
    opacity: 1 !important;
    transform: none !important;
  }
  
  .intro-overlay__background {
    opacity: 1 !important;
    transform: none !important;
  }
  
  .intro-overlay__skip {
    opacity: 0.8 !important;
    transform: none !important;
  }
  
  .intro-overlay__halo {
    opacity: 0.3 !important;
    transform: translate(-50%, -50%) !important;
  }
}

/* === Print Styles === */
@media print {
  .intro-overlay {
    display: none !important;
  }
}

/* === Fallback No-JS === */
.no-js .intro-overlay {
  display: none !important;
}

/* === Dark mode enhancement === */
@media (prefers-color-scheme: dark) {
  :root {
    --intro-bg-primary: rgba(8, 8, 18, 0.98);
    --intro-bg-secondary: rgba(3, 3, 12, 0.99);
  }
}

/* Ensure split spans keep spacing consistent */
.intro-overlay__text span {
  white-space: normal; /* allow normal wrapping so multi-line center works */
}

/* === Progress Bar === */
.intro-overlay__progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  background: rgba(255, 255, 255, 0.06);
  overflow: hidden;
  z-index: 12;
  transform: translateZ(0);
}

.intro-overlay__progress-bar {
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, var(--intro-accent-gold), var(--intro-accent-purple));
  transform: scaleX(0);
  transform-origin: left center;
  will-change: transform;
}

@media (prefers-reduced-motion: reduce) {
  .intro-overlay__progress-bar { transition: none !important; animation: none !important; }
}

/* Skip Button Additional */
.intro-overlay__skip-alt {
  position: absolute;
  top: 20px;
  left: 20px;
  z-index: 10;
  background: rgba(0, 0, 0, 0.6);
  color: var(--intro-text-secondary);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 20px;
  padding: 8px 16px;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  backdrop-filter: blur(8px);
  transition: all var(--intro-duration-fast) var(--intro-timing);
}

.intro-overlay__skip-alt:hover,
.intro-overlay__skip-alt:focus-visible {
  background: rgba(0, 0, 0, 0.8);
  color: var(--intro-text-primary);
  border-color: var(--intro-accent-gold);
  transform: translateY(-2px);
  box-shadow: var(--intro-shadow-strong);
}

.intro-overlay__skip-alt:focus-visible {
  outline: 2px solid var(--intro-accent-blue);
  outline-offset: 2px;
}

.intro-overlay__skip-alt:active {
  transform: translateY(0);
  opacity: 0.9;
}
/* Helper to lock transforms during outro to avoid jumping */
.intro-overlay--lock .intro-overlay__phase { transform: none !important; }