<div class="radikalwp-fm-select"><select><option>همه شهرها<//option><option>تهران<//option><option>اصفهان<//option><option>شیراز<//option><//select><//div>

.radikalwp-fm-select { position: relative; width: 220px; }
.radikalwp-fm-select::after {
  content: '▾';
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: #64748b;
  pointer-events: none;
  font-size: 13px;
}
.radikalwp-fm-select select {
  width: 100%;
  padding: 12px 14px;
  font-family: inherit;
  font-size: 13.5px;
  color: #0f172a;
  background: #fff;
  border: 1.5px solid #e2e8f0;
  border-radius: 12px;
  outline: none;
  appearance: none;
  cursor: pointer;
  transition: border-color .25s ease;
}
.radikalwp-fm-select select:focus { border-color: #4f46e5; box-shadow: 0 0 0 3px rgba(79, 70, 229, .12); }