preventing Vue from aggresively reusing dom-elements
In cases such as this, Vue uses a special key attribute that tells it not to reuse the same element. Give each element this attribute with a unique value, and Vue will no longer reuse the same element:
<div v-if="tryIsMobile" class="device device-mobile-portrait" :class="deviceClass" key="mobile"> ...</div><div v-else class="device device-tablet-landscape" :class="deviceClass" key="tablet"> ...</div>