/* Buttons - Core and Variants */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.75em;
  position: relative;
  min-width: var(--btn-min-width);
  min-height: clamp(44px, var(--btn-min-height), 100%);
  max-width: 100%;
  padding-inline: var(--btn-padding-inline, 2.5em);
  padding-block: var(--btn-padding-block, 1.1em);
  font-family: var(--body-font);
  font-weight: 600;
  font-size: var(--btn-font-size);
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--text-on-primary);
  border: 2px solid transparent;
  border-radius: var(--btn-border-radius);
  background-color: transparent;
  box-shadow: var(--btn-shadow);
  transition:
    background-position var(--btn-transition),
    box-shadow var(--btn-transition),
    transform var(--btn-transition),
    color var(--btn-transition),
    background-color var(--btn-transition)
	border-color var(--btn-transition);
  cursor: pointer;
  appearance: none;
  user-select: none;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  will-change: transform;
  transform-origin: center;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

@media (hover: hover) {
  .btn:hover {
    transform: translate3d(0, -2px, 0);
    box-shadow: var(--btn-shadow-hover);
  }
}

.btn:active {
  transform: translate3d(0, 1px, 0);
  box-shadow: var(--btn-shadow-active);
  transition-duration: 0.1s;
}

.btn:focus-visible {
  outline: var(--focus-width) solid var(--focus-ring);
  outline-offset: var(--focus-offset);
}

.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
  filter: saturate(0.5);
}

/* Primary / Secondary */
.btn--primary {
  background-image: linear-gradient(135deg, var(--primary-medium-light), var(--primary));
  background-size: 200% auto;
  background-position: right center;
  background-repeat: no-repeat;
  color: var(--text-on-primary);
  border-color: var(--primary);
}
.btn--primary:hover {
  background-position: left center;
  box-shadow:
    var(--btn-shadow-hover),
    var(--btn-glow-primary),
    inset 0 0 0 1px var(--btn-inner-glow);
}

.btn--secondary {
  background-image: linear-gradient(135deg, var(--secondary), var(--secondary-medium-light));
  background-size: 200% auto;
  background-position: right center;
  background-repeat: no-repeat;
  color: var(--text-on-secondary);
  border-color: var(--secondary-hover);
}
.btn--secondary:hover {
  background-position: left center;
  box-shadow:
    var(--btn-shadow-hover),
    var(--btn-glow-secondary),
    inset 0 0 0 1px var(--btn-inner-glow);
}

/* Outline */
.btn--primary-outline {
  background-color: transparent;
  color: var(--primary);
  border-color: var(--primary);
}
.btn--primary-outline:hover {
  background-color: var(--primary);
  color: var(--text-on-primary);
}

.btn--secondary-outline {
  background-color: transparent;
  color: var(--secondary);
  border-color: var(--secondary);
}
.btn--secondary-outline:hover {
  background-color: var(--secondary);
  color: var(--text-on-secondary);
}

/* Ghost */
.btn--ghost {
  background: transparent;
  color: var(--text-primary);
  border: none;
  box-shadow: none;
}
.btn--ghost:hover {
  background: rgba(0, 0, 0, 0.05);
  backdrop-filter: blur(2px);
}
.btn--ghost:active {
  background: rgba(0, 0, 0, 0.1);
}

/* Icon Only */
.btn--icon-only {
  aspect-ratio: 1 / 1;
  padding: 0 !important;
  min-width: auto !important;
  max-width: none;
}
.btn--icon-only svg {
  width: 1em;
  height: 1em;
}
@media (max-width: 480px) {
  .btn--icon-only { font-size: 1.4rem; }
}
@supports not (aspect-ratio: 1 / 1) {
  .btn--icon-only { width: 44px; height: 44px; }
}
.btn--icon-only[aria-label]:not([aria-label=""])::after {
  content: attr(aria-label);
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

/* Size Variants */
.btn--sm {
  min-height: 3.2rem;
  padding-inline: 1.5em;
  padding-block: 0.75em;
  font-size: 1.4rem;
}
.btn--lg {
  min-height: 5rem;
  padding-inline: 3em;
  padding-block: 1.25em;
  font-size: 1.8rem;
}

/* Button Group */
.button-group {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  justify-content: center;
}
.button-group--left { justify-content: flex-start; }
.button-group--right { justify-content: flex-end; }
.button-group--center { justify-content: center; }
.button-group--space-between { justify-content: space-between; }

@media (max-width: 768px) {
  .button-group {
    flex-direction: column;
    gap: 1rem;
    width: 100%;
  }
  .button-group .btn:not(.btn--icon-only):not(.btn--ghost) {
    width: 100%;
    font-size: calc(var(--btn-font-size) - 0.1rem);
  }
}