/* ============================================
   Braintube – Premium Page Loader
   Animated loading screen with logo pulse
   ============================================ */

.bt-loader {
  position: fixed;
  inset: 0;
  z-index: 99999;
  background: #09090b;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 28px;
  transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1),
              visibility 0.5s;
}

.bt-loader.hide {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

/* Logo Container */
.bt-loader-logo {
  position: relative;
  width: 72px;
  height: 72px;
}

/* The "B" Logo */
.bt-loader-logo .logo-mark {
  width: 72px;
  height: 72px;
  border-radius: 18px;
  background: linear-gradient(135deg, #8b5cf6 0%, #06b6d4 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Outfit', 'Inter', sans-serif;
  font-size: 2.2rem;
  font-weight: 800;
  color: white;
  animation: bt-logo-pulse 1.8s ease-in-out infinite;
  box-shadow: 0 0 40px rgba(139, 92, 246, 0.3),
              0 0 80px rgba(6, 182, 212, 0.15);
}

/* Rotating ring */
.bt-loader-logo .logo-ring {
  position: absolute;
  inset: -8px;
  border-radius: 24px;
  border: 2px solid transparent;
  border-top-color: #8b5cf6;
  border-right-color: #06b6d4;
  animation: bt-ring-spin 1.2s linear infinite;
}

/* Second ring (counter-rotate) */
.bt-loader-logo .logo-ring-2 {
  position: absolute;
  inset: -16px;
  border-radius: 30px;
  border: 1px solid transparent;
  border-bottom-color: rgba(139, 92, 246, 0.3);
  border-left-color: rgba(6, 182, 212, 0.2);
  animation: bt-ring-spin 2s linear infinite reverse;
}

/* Brand text */
.bt-loader-brand {
  font-family: 'Outfit', 'Inter', sans-serif;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: rgba(255, 255, 255, 0.85);
  text-transform: uppercase;
}
.bt-loader-brand span {
  background: linear-gradient(135deg, #a78bfa, #22d3ee);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Progress bar */
.bt-loader-progress {
  width: 160px;
  height: 3px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 10px;
  overflow: hidden;
}
.bt-loader-progress .bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #8b5cf6, #06b6d4);
  border-radius: 10px;
  animation: bt-progress 1.5s ease-out forwards;
}

/* Floating particles */
.bt-loader-particles {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}
.bt-loader-particles .particle {
  position: absolute;
  border-radius: 50%;
  animation: bt-float-up linear infinite;
  opacity: 0;
}
.bt-loader-particles .particle:nth-child(1) {
  width: 3px; height: 3px;
  background: #8b5cf6;
  left: 20%; bottom: -10px;
  animation-duration: 4s; animation-delay: 0s;
}
.bt-loader-particles .particle:nth-child(2) {
  width: 2px; height: 2px;
  background: #06b6d4;
  left: 45%; bottom: -10px;
  animation-duration: 3.5s; animation-delay: 0.5s;
}
.bt-loader-particles .particle:nth-child(3) {
  width: 4px; height: 4px;
  background: #a78bfa;
  left: 70%; bottom: -10px;
  animation-duration: 5s; animation-delay: 1s;
}
.bt-loader-particles .particle:nth-child(4) {
  width: 2px; height: 2px;
  background: #22d3ee;
  left: 85%; bottom: -10px;
  animation-duration: 3s; animation-delay: 0.3s;
}
.bt-loader-particles .particle:nth-child(5) {
  width: 3px; height: 3px;
  background: #7c3aed;
  left: 10%; bottom: -10px;
  animation-duration: 4.5s; animation-delay: 0.8s;
}
.bt-loader-particles .particle:nth-child(6) {
  width: 2px; height: 2px;
  background: #67e8f9;
  left: 55%; bottom: -10px;
  animation-duration: 3.8s; animation-delay: 1.2s;
}

/* Subtle tagline */
.bt-loader-tagline {
  font-family: 'Inter', sans-serif;
  font-size: 0.72rem;
  color: rgba(255, 255, 255, 0.25);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  animation: bt-fade-in 0.8s ease 0.3s both;
}

/* ====== KEYFRAMES ====== */
@keyframes bt-logo-pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.06); }
}

@keyframes bt-ring-spin {
  to { transform: rotate(360deg); }
}

@keyframes bt-progress {
  0% { width: 0%; }
  40% { width: 60%; }
  80% { width: 85%; }
  100% { width: 100%; }
}

@keyframes bt-float-up {
  0% { transform: translateY(0) scale(1); opacity: 0; }
  10% { opacity: 0.6; }
  90% { opacity: 0.3; }
  100% { transform: translateY(-100vh) scale(0.5); opacity: 0; }
}

@keyframes bt-fade-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Prevent scroll while loading */
body.bt-loading {
  overflow: hidden;
}