.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 15.5px;
  border: 1.5px solid transparent;
  overflow: hidden;
  white-space: nowrap;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease, color 0.25s ease, border-color 0.25s ease;
  will-change: transform;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: scale(0.98); }

.btn::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 60px;
  background: linear-gradient(105deg, transparent, rgba(255,255,255,0.45), transparent);
  right: -80px;
  transform: skewX(-20deg);
  transition: right 0.6s ease;
  pointer-events: none;
}
.btn:hover::after { right: calc(100% + 80px); }

.btn--primary {
  background: var(--primary-gradient);
  color: #fff;
  box-shadow: var(--shadow-md);
}
.btn--primary:hover { box-shadow: var(--shadow-lg), 0 0 24px color-mix(in srgb, var(--accent-500) 35%, transparent); }

.btn--ghost {
  background: var(--surface);
  color: var(--primary-500);
  border-color: var(--border-strong);
}
[data-theme="dark"] .btn--ghost { color: var(--text); }
.btn--ghost:hover { border-color: var(--primary-500); box-shadow: var(--shadow-md), 0 0 18px color-mix(in srgb, var(--primary-500) 25%, transparent); }

.btn--light {
  background: #fff;
  color: var(--primary-700);
}
.btn--light:hover { box-shadow: 0 12px 30px rgba(0,0,0,0.25), 0 0 18px rgba(255,255,255,0.35); }

.btn--outline-light {
  border-color: rgba(255,255,255,0.5);
  color: #fff;
}
.btn--outline-light:hover { background: rgba(255,255,255,0.14); box-shadow: 0 0 18px rgba(255,255,255,0.25); }

.btn--sm { padding: var(--space-2) var(--space-4); font-size: 14px; }
.btn--phone { direction: ltr; font-variant-numeric: tabular-nums; }

.backtop {
  position: fixed;
  bottom: 28px;
  left: 28px;
  width: 52px;
  height: 52px;
  border-radius: 16px;
  background: var(--primary-gradient);
  color: #fff;
  display: grid;
  place-items: center;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(16px);
  pointer-events: none;
  transition: opacity 0.25s ease, transform 0.25s ease, box-shadow 0.25s ease;
  z-index: 900;
}
.backtop.show { opacity: 1; transform: none; pointer-events: auto; }
.backtop.show:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg), 0 0 20px color-mix(in srgb, var(--accent-500) 35%, transparent); }
.backtop.show:active { transform: scale(0.98); }
.backtop svg { width: 22px; height: 22px; }

@media (hover: none), (pointer: coarse) {
  .btn:hover, .backtop.show:hover { transform: none; box-shadow: var(--shadow-md); }
  .btn::after { display: none; }
  .btn:active, .backtop.show:active { transform: scale(0.98); }
}

@media (prefers-reduced-motion: reduce) {
  .btn, .backtop { transition: none; }
  .btn:hover, .backtop.show:hover { transform: none; }
  .btn::after { display: none; }
  .btn:active, .backtop.show:active { transform: none; }
}