/* =============================================================================
   @elements/style — button

   Three primary variants:
     .btn-primary   — ink fill (default CTA — install, sign in, submit)
     .btn-secondary — ghost / outlined (watch tutorial, learn more, cancel)
     .btn-accent    — rust fill (reserved for the single highest-value CTA
                      per conversion page — hero trial, pricing buy)

   Sizes (height):
     .btn-sm  — 36px
     .btn     — 44px (default)
     .btn-lg  — 48px (hero CTAs, top-of-signup)

   Hover is always `opacity: 0.9` for filled buttons and `border-color:
   var(--ink)` for ghosts. No glows, no shadows, no scale transforms.

   Focus is a crisp solid ink outline with 2px offset. No halo.
============================================================================= */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2-5);
  height: var(--button-height);
  padding: 0 var(--button-padding-x);
  font-family: var(--font-mono);
  font-size: var(--button-font-size);
  font-weight: var(--button-font-weight);
  line-height: 1;
  letter-spacing: var(--tracking-normal);
  white-space: nowrap;
  text-decoration: none;
  border-radius: var(--button-radius);
  cursor: pointer;
  user-select: none;
  border: 1px solid transparent;
  transition:
    background-color 150ms var(--ease-out),
    border-color 150ms var(--ease-out),
    color 150ms var(--ease-out),
    transform 80ms var(--ease-out),
    box-shadow 150ms var(--ease-out),
    opacity 150ms var(--ease-out);
}

.btn:focus { outline: none; }

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

/* ─── Variants ────────────────────────────────────────────────────── */

.btn-primary {
  background: var(--ink);
  color: #ffffff;
  border-color: var(--ink);
}
.btn-primary:hover { background: #2a2a2f; border-color: #2a2a2f; }
.btn-primary:active {
  background: #000;
  border-color: #000;
  transform: translateY(1px);
}
.btn-primary:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 2px var(--bg),
    0 0 0 4px var(--ink);
}
.btn-primary:disabled {
  background: var(--ink-faint);
  border-color: var(--ink-faint);
  color: #ffffff;
}
.btn-primary .arrow { color: rgba(255, 255, 255, 0.5); }

.btn-secondary {
  background: transparent;
  color: var(--ink);
  border-color: var(--rule);
}
.btn-secondary:hover {
  border-color: var(--ink);
  background: var(--bg-soft);
}
.btn-secondary:active {
  border-color: var(--ink);
  background: var(--bg-panel);
  transform: translateY(1px);
}
.btn-secondary:focus-visible {
  outline: none;
  border-color: var(--ink);
  box-shadow:
    0 0 0 2px var(--bg),
    0 0 0 4px var(--ink);
}
.btn-secondary:disabled {
  color: var(--ink-dim);
  border-color: var(--rule);
  background: transparent;
  opacity: 0.6;
}

.btn-accent {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}
.btn-accent:hover { background: var(--accent-deep); border-color: var(--accent-deep); }
.btn-accent:active { transform: translateY(1px); }
.btn-accent:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 2px var(--bg),
    0 0 0 4px var(--accent-deep);
}

.btn-ghost {
  background: transparent;
  color: var(--ink-soft);
  border-color: transparent;
}
.btn-ghost:hover { color: var(--ink); background: var(--bg-panel); }
.btn-ghost:active { transform: translateY(1px); }
.btn-ghost:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 2px var(--bg),
    0 0 0 4px var(--ink);
}

.btn-danger {
  background: var(--danger);
  color: #ffffff;
  border-color: var(--danger);
}
.btn-danger:hover { opacity: 0.9; }
.btn-danger:active { transform: translateY(1px); }
.btn-danger:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 2px var(--bg),
    0 0 0 4px var(--danger);
}

/* ─── Sizes ───────────────────────────────────────────────────────── */

.btn-sm {
  height: var(--button-height-sm);
  padding: 0 var(--space-3);
  font-size: var(--text-xs);
}

.btn-lg {
  height: var(--button-height-lg);
  padding: 0 var(--space-5);
  font-size: var(--text-md);
}

/* ─── Block — full width ─────────────────────────────────────────── */

.btn-block {
  display: flex;
  width: 100%;
}

/* ─── Arrow affordance ───────────────────────────────────────────────
   Use: <a class="btn btn-primary">Install <span class="arrow">→</span></a>
   Keeps the arrow muted in the button's color family. */

.btn .arrow {
  color: currentColor;
  opacity: 0.5;
  transition: opacity var(--duration-fast) var(--ease-out);
}
.btn:hover .arrow { opacity: 0.7; }