/* =============================================================
   COMPONENT — BUTTON
   ============================================================= */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 0.75rem 1.75rem;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  transition: background var(--transition-fast),
              border-color var(--transition-fast),
              color var(--transition-fast),
              box-shadow var(--transition-fast),
              transform var(--transition-fast),
              opacity var(--transition-fast);
}

.btn:active {
  transform: translateY(1px);
}

/* --- Primary --- */
.btn--primary {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #fff;
  box-shadow: var(--shadow-accent-btn);
}

.btn--primary:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent-light);
  box-shadow: 0 4px 28px rgba(155,114,232,0.45), 0 0 0 1px rgba(155,114,232,0.3);
}

.btn--primary:focus-visible {
  outline: 2px solid var(--color-accent-light);
  outline-offset: 3px;
}

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

.btn--outline:hover {
  background: var(--color-bg-hover);
  border-color: var(--color-accent-border);
  color: var(--color-text-primary);
}

.btn--outline:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

/* --- Ghost --- */
.btn--ghost {
  background: transparent;
  border-color: transparent;
  color: var(--color-text-secondary);
  padding-inline: var(--space-3);
}

.btn--ghost:hover {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

/* --- Accent Outline --- */
.btn--accent-outline {
  background: transparent;
  border-color: var(--color-accent-border);
  color: var(--color-text-accent);
}

.btn--accent-outline:hover {
  background: var(--color-accent-dim);
  border-color: var(--color-accent);
  color: var(--color-accent-light);
}

/* --- Sizes --- */
.btn--sm {
  padding: 0.5rem 1.2rem;
  font-size: var(--text-xs);
}

.btn--lg {
  padding: 1rem 2.5rem;
  font-size: var(--text-base);
}

.btn--xl {
  padding: 1.1rem 3rem;
  font-size: var(--text-base);
  letter-spacing: 0.08em;
}

/* --- Icon button --- */
.btn--icon {
  padding: 0.6rem;
  border-radius: var(--radius-sm);
  aspect-ratio: 1;
}

/* --- Full width --- */
.btn--full {
  width: 100%;
}

/* --- Disabled --- */
.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}

/* --- Loading state --- */
.btn--loading {
  pointer-events: none;
}

.btn--loading::after {
  content: '';
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: btn-spin 0.6s linear infinite;
}

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