Check out example codes for "change border highlight color on an input text element". It will help you in understanding the concepts better.

Code Example 1

input:focus { 
    outline: none !important;
    border-color: #719ECE;
    box-shadow: 0 0 10px #719ECE;
}
textarea:focus { 
    outline: none !important;
    border-color: #719ECE;
    box-shadow: 0 0 10px #719ECE;
}

Code Example 2

.input:focus {
    outline: none !important;
    border:1px solid red;
    box-shadow: 0 0 10px #719ECE;
}

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