// Add after Materialize. Opt-in classes preserve existing .btn styling elsewhere.
.btn.btn-expressive {
  --button-height: 40px;
  --button-padding: 24px;
  --button-icon: 20px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: var(--button-height);
  min-height: var(--button-height);
  padding: 0 var(--button-padding);
  border-radius: 999px;
  font-size: 14px;
  line-height: 1.2;
  text-transform: none;
  white-space: nowrap;
  transition:
    border-radius 180ms ease,
    background-color 180ms ease,
    flex-grow 180ms ease;
  /// Give every icon font the same size instead of inheriting the smaller label size.
  > i,
  > .material-icons {
    position: static;
    transform: none;
    font-size: var(--button-icon);
    line-height: 1;
    flex-shrink: 0;
  }
  &:focus-visible {
    outline: 3px solid var(--md-sys-color-on-surface);
    outline-offset: 3px;
  }
  &:active:not(:disabled) {
    border-radius: 12px;
  }
  &.btn-xs {
    --button-height: 32px;
    --button-padding: 12px;
  }
  &.btn-sm {
    --button-height: 40px;
  }
  &.btn-md {
    --button-height: 56px;
    --button-icon: 24px;
    font-size: 16px;
  }
  &.btn-lg {
    --button-height: 96px;
    --button-padding: 40px;
    --button-icon: 32px;
    font-size: 24px;
  }
  &.btn-xl {
    --button-height: 136px;
    --button-padding: 48px;
    --button-icon: 40px;
    font-size: 32px;
  }
  &.btn-square {
    border-radius: calc(var(--button-height) * 0.28);
  }
}

// Toggle state belongs in aria-pressed, so visual and accessible states agree.
.btn.btn-toggle[aria-pressed="true"] {
  background: var(--md-sys-color-primary);
  color: var(--md-sys-color-on-primary);
  border-color: transparent;
  border-radius: 16px;
}
.btn.btn-icon {
  width: var(--button-height);
  min-width: var(--button-height);
  padding: 0;
}
.btn.btn-icon-standard {
  background: transparent;
  color: var(--md-sys-color-on-surface-variant);
  box-shadow: none;
}
.btn.btn-icon-standard:hover:not(:disabled) {
  background: var(--md-sys-color-surface-variant);
}
.btn.btn-icon.btn-toggle[aria-pressed="true"] {
  background: var(--md-sys-color-primary);
  color: var(--md-sys-color-on-primary);
}
.btn.btn-icon.btn-icon-narrow {
  width: calc(var(--button-height) * 0.8);
  min-width: calc(var(--button-height) * 0.8);
}
.btn.btn-icon.btn-icon-wide {
  width: calc(var(--button-height) * 1.5);
}

// Standard groups keep gaps; connected groups share the outer silhouette.
.btn-group {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: 100%;
}
.btn-group > .btn {
  flex: 1 1 0;
  min-width: 0;
}
.btn-group-standard {
  width: 100%;
  max-width: 480px;
}
.btn-group-standard > .btn:hover:not(:disabled) {
  flex-grow: 1.2;
}
.btn-group-connected {
  gap: 2px;
}
.btn-group-connected > .btn.btn-expressive {
  border-radius: 4px;
}
.btn-group-connected > .btn.btn-expressive:first-child {
  border-start-start-radius: 999px;
  border-end-start-radius: 999px;
}
.btn-group-connected > .btn.btn-expressive:last-child {
  border-start-end-radius: 999px;
  border-end-end-radius: 999px;
}
// Keep the connected silhouette unchanged during selection and pointer presses.
.btn-group-connected > .btn.btn-expressive:active:not(:disabled) {
  border-radius: 4px;
  &:first-child {
    border-start-start-radius: 999px;
    border-end-start-radius: 999px;
  }
  &:last-child {
    border-start-end-radius: 999px;
    border-end-end-radius: 999px;
  }
}

// Split controls expose a separate primary action and menu action.
.btn-split {
  display: inline-flex;
  gap: 2px;
  position: relative;
  vertical-align: middle;
}
.btn-split > .btn:first-child {
  border-start-end-radius: 4px;
  border-end-end-radius: 4px;
}
.btn-split > .btn-menu-trigger {
  border-start-start-radius: 4px;
  border-end-start-radius: 4px;
}
.btn-menu-trigger > .material-icons {
  transition: transform 180ms ease;
}
.btn-menu-trigger[aria-expanded="true"] > .material-icons {
  transform: rotate(180deg);
}
// FABs use container colors and elevation; extended FABs also carry a label.
.btn.btn-fab {
  --button-height: 56px;
  --button-icon: 24px;
  width: var(--button-height);
  padding: 0;
  border-radius: 16px;
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
  box-shadow: 0 3px 8px
    color-mix(in srgb, var(--md-sys-color-shadow) 20%, transparent);
  &.fab-secondary {
    background: var(--md-sys-color-secondary-container);
    color: var(--md-sys-color-on-secondary-container);
  }
  &.fab-tertiary {
    background: var(--md-sys-color-tertiary-container);
    color: var(--md-sys-color-on-tertiary-container);
  }
  &.fab-small {
    --button-height: 40px;
    border-radius: 12px;
  }
  &.fab-large {
    --button-height: 96px;
    --button-icon: 36px;
    border-radius: 28px;
  }
  &.btn-fab-extended {
    width: auto;
    padding: 0 20px;
  }
}
.btn-fab-menu {
  position: relative;
  display: inline-flex;
}
.btn-fab-menu .btn-menu-trigger[aria-expanded="true"] > .material-icons {
  transform: rotate(45deg);
}

/// Use half the height so CSS radius normalization preserves the 4px inner corners.
.btn.btn-expressive.btn-round-left {
  &, &:active:not(:disabled), &[aria-pressed="true"] {
    border-radius: calc(var(--button-height) / 2) 4px 4px calc(var(--button-height) / 2);
  }
}
.btn.btn-expressive.btn-round-right {
  &, &:active:not(:disabled), &[aria-pressed="true"] {
    border-radius: 4px calc(var(--button-height) / 2) calc(var(--button-height) / 2) 4px;
  }
}

// Explicitly retain native disabled behavior across all custom variants.
.btn.btn-expressive:disabled,
.btn.btn-expressive.btn-toggle:disabled {
  background: color-mix(
    in srgb,
    var(--md-sys-color-on-surface) 12%,
    transparent
  );
  color: color-mix(in srgb, var(--md-sys-color-on-surface) 38%, transparent);
  box-shadow: none;
  cursor: default;
}
@media (pointer: coarse) {
  .btn.btn-expressive::after {
    content: "";
    position: absolute;
    inset: -4px 0;
    min-height: 48px;
  }
  .btn-group {
    gap: 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .btn.btn-expressive,
  .btn-menu-trigger > .material-icons {
    transition: none;
  }
}