body:has(> .line-contact) {
  --line-edge: 24px;
  --line-bottom: max(var(--line-edge), env(safe-area-inset-bottom, 0px));
  --line-size: 46px;
}

.line-contact {
  position: fixed;
  right: max(var(--line-edge), env(safe-area-inset-right, 0px));
  bottom: var(--line-bottom);
  z-index: 94;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: var(--line-size);
  padding: 0 14px;
  border: 1px solid #066341;
  border-radius: 999px;
  background: #08784c;
  color: #fff;
  box-shadow: 0 4px 16px rgba(4, 40, 29, .18);
  font: 700 13px/1.2 Manrope, "Noto Sans TC", sans-serif;
  text-decoration: none;
}

.line-contact:hover { background: #066341; color: #fff; }
.line-contact:focus-visible { outline: 2px solid #fff; outline-offset: 2px; box-shadow: 0 0 0 5px #066341; }
.line-contact svg { width: 17px; height: 17px; fill: currentColor; }

body:has(> .line-contact) .back-to-top {
  bottom: calc(var(--line-bottom) + var(--line-size) + 10px);
}

@media (max-width: 640px) {
  body:has(> .line-contact) { --line-edge: 18px; }
}