<button class="btn-calc">
  <span class="btn-calc-cap">
    <span class="btn-calc-glyph">=</span>
    <span class="btn-calc-label">EQUAL</span>
  </span>
</button>

.btn-calc {
  display: inline-block;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
}
.btn-calc-cap {
  display: inline-flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 2px;
  width: 84px; height: 64px;
  background: linear-gradient(180deg, #ebe4d3 0%, #d8d2c0 60%, #c0b9a3 100%);
  border-radius: 6px;
  box-shadow:
    inset 0 -6px 8px rgba(0,0,0,0.12),
    inset 0 2px 3px rgba(255,255,255,0.7),
    0 4px 0 #4d5435,
    0 6px 12px rgba(0,0,0,0.2);
  transition: transform 0.08s ease, box-shadow 0.08s ease;
}
.btn-calc-glyph {
  font-family: ui-monospace, monospace;
  font-size: 22px; font-weight: 900;
  color: #4d5435;
}
.btn-calc-label {
  font-family: ui-monospace, monospace;
  font-size: 8px; font-weight: 700;
  letter-spacing: 0.18em;
  color: #4d5435;
  opacity: 0.8;
}
.btn-calc:active .btn-calc-cap {
  transform: translateY(3px);
  box-shadow:
    inset 0 -2px 4px rgba(0,0,0,0.18),
    inset 0 2px 3px rgba(255,255,255,0.5),
    0 1px 0 #4d5435,
    0 2px 4px rgba(0,0,0,0.15);
}