@dobbel So what I did was the following and it works perfectly so far:
In app.sass
.lm-input-hilight.q-field--focused.q-field--outlined .q-field__control::after
box-shadow: 0 0 5px rgba(81, 203, 238, 1)
border: 1px solid rgba(81, 203, 238, 1)
I then simply applied my lm-input-hilight class as follows:
<q-input outlined dense class="lm-input-hilight" v-model="lmGlobalSearch" bg-color="white" placeholder="Search...">
<template v-slot:prepend>
<q-icon class="text-grey-5" name="search" />
</template>
</q-input>
Thanks for your input, it led me to where I needed to be! 
