/* Back to Top Button Styles - The Vivid Disc Concept */
#et-btt {
  position: fixed;
  right: calc(20px + env(safe-area-inset-right));
  bottom: calc(20px + env(safe-area-inset-bottom));
  z-index: 9999;
  opacity: 0;
  transform: translateY(15px) scale(0.95);
  pointer-events: none;
  transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1), transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

#et-btt.is-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

#et-btt .et-btt__btn {
  position: relative;
  display: grid;
  place-items: center;
  width: var(--et-btt-size, 52px); /* Default size reduced */
  height: var(--et-btt-size, 52px); /* Default size reduced */
  border-radius: 50%; /* Perfect circle */
  cursor: pointer;
  outline: none;
  border: none;
  
  /* Solid, opaque background for high visibility */
  background: #4361EE; /* Primary Blue */
  color: #ffffff; /* White icon */
  
  box-shadow: 
    0 8px 24px rgba(67, 97, 238, 0.25),
    0 4px 12px rgba(0, 0, 0, 0.15);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  overflow: hidden;
}

/* Hover State - Transitions to the vibrant gradient */
#et-btt .et-btt__btn:hover {
  transform: translateY(-6px) scale(1.05);
  background: linear-gradient(135deg, #4361EE 0%, #7209B7 100%);
  box-shadow: 
    0 16px 32px rgba(67, 97, 238, 0.3),
    0 8px 24px rgba(114, 9, 183, 0.2);
}

/* Active press with tactile feedback */
#et-btt .et-btt__btn:active {
  transform: translateY(-2px) scale(0.96);
  box-shadow: 0 4px 16px rgba(67, 97, 238, 0.3);
}

/* Progress ring perfectly centered */
#et-btt .et-btt__ring {
  position: absolute;
  width: 100%;
  height: 100%;
}

#et-btt .et-btt__ring-track {
  fill: none;
  stroke: rgba(255, 255, 255, 0.2);
  stroke-width: 3;
}

#et-btt .et-btt__ring-indicator {
  fill: none;
  stroke: #ffe066; /* CHANGED: Progress indicator color */
  stroke-width: 3;
  stroke-linecap: round;
  transform: rotate(-90deg);
  transform-origin: 50% 50%;
  filter: drop-shadow(0 0 4px rgba(255, 224, 102, 0.5)); /* Adjusted drop-shadow */
  transition: stroke-dashoffset 0.2s linear;
}

/* Icon perfectly centered */
#et-btt .et-btt__icon {
  position: relative;
  z-index: 2;
  width: 22px; /* Adjusted for smaller button */
  height: 22px; /* Adjusted for smaller button */
}

/* Responsive design for smaller screens */
@media (max-width: 768px) {
  #et-btt {
    right: calc(16px + env(safe-area-inset-right));
    bottom: calc(16px + env(safe-area-inset-bottom));
  }
  
  #et-btt .et-btt__btn {
    width: var(--et-btt-size, 48px); /* Further reduced for mobile */
    height: var(--et-btt-size, 48px); /* Further reduced for mobile */
  }
  
  #et-btt .et-btt__icon {
    width: 20px;
    height: 20px;
  }
}

/* High contrast mode for accessibility */
@media (prefers-contrast: high) {
  #et-btt .et-btt__btn {
    border: 2px solid;
    background: Canvas;
    color: CanvasText;
  }
  #et-btt .et-btt__btn:hover {
    background: Highlight;
    color: HighlightText;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  #et-btt .et-btt__btn,
  #et-btt {
    transition-duration: 0.01ms !important;
  }
}

/* Focus states for keyboard navigation */
#et-btt .et-btt__btn:focus-visible {
  outline: 3px solid #4361EE;
  outline-offset: 3px;
  background: linear-gradient(135deg, #4361EE 0%, #7209B7 100%);
}