<div class="radikalwp-form-select"><select class="radikalwp-form-select-el" aria-label="انتخاب استان"><option value="" selected disabled>انتخاب استان...<//option><option>تهران<//option><option>اصفهان<//option><option>فارس<//option><option>خراسان رضوی<//option><//select><span class="radikalwp-form-select-arrow" aria-hidden="true">▾<//span><//div>

.radikalwp-form-select {
  position: relative;
  max-width: 280px;
}
.radikalwp-form-select-el {
  width: 100%;
  appearance: none;
  -webkit-appearance: none;
  padding: 12px 16px;
  font-family: inherit;
  font-size: 14px;
  color: #1e293b;
  background: #fff;
  border: 1.5px solid #e2e8f0;
  border-radius: 12px;
  outline: none;
  cursor: pointer;
  transition: border-color .25s ease, box-shadow .25s ease;
}
.radikalwp-form-select-el:focus {
  border-color: #6366f1;
  box-shadow: 0 0 0 4px rgba(99, 102, 241, .14);
}
.radikalwp-form-select-arrow {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: #94a3b8;
  font-size: 14px;
  pointer-events: none;
  transition: transform .25s ease, color .25s ease;
}
.radikalwp-form-select-el:focus ~ .radikalwp-form-select-arrow {
  transform: translateY(-50%) rotate(180deg);
  color: #6366f1;
}