.stack { padding: 112px 0; }
.stack__grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.stack-card {
  display: flex; flex-direction: column; gap: 12px;
  padding: 26px; border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--surface); transition: border-color .15s ease, box-shadow .15s ease;
}
.stack-card:hover { border-color: var(--red); box-shadow: var(--shadow-sm); }
.stack-card__layer { color: var(--red); font-size: 12px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.stack-card h3 { color: var(--heading); font-size: 19px; line-height: 1.3; }
.stack-card p { color: var(--text-soft); font-size: 14px; line-height: 1.55; }
.stack__note { max-width: 900px; margin: 32px auto 0; color: var(--text-mute); font-size: 14px; line-height: 1.6; text-align: center; }
@media (max-width: 960px) { .stack__grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 620px) { .stack { padding: 64px 0; } .stack__grid { grid-template-columns: 1fr; } }