html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  -webkit-tap-highlight-color: transparent;
}

body {
  margin: 0;
  overscroll-behavior-y: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
}

/* Touch responsiveness optimization (removes 300ms tap delay on mobile) */
button, a, input, select, textarea {
  touch-action: manipulation;
  font: inherit;
}

button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 3px solid rgba(59, 130, 246, 0.35);
  outline-offset: 2px;
}

.ui-icon {
  width: 1.1em;
  height: 1.1em;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  vertical-align: -0.15em;
  pointer-events: none;
}

/* Smooth GPU composite layer for active modes */
main > section.active {
  contain: content;
  transform: translateZ(0);
}

/* Optimize smooth scrolling list rendering */
.word-grid, .tr-review-body {
  -webkit-overflow-scrolling: touch;
  content-visibility: auto;
}