JSFiddle - React, Tailwind, and code Playground

HTML

<div id="timer">
    <input id="minutes" type="text"/>
    <span id="colon">:</span>
    <input id="seconds" type="text" />
</div>

CSS

#colon {
        font-size: 50px;
}

input {
    width: 60px;
    border: none;
    background-color:none; 
    font-size: 50px; 
    font-weight: bold;
}

#minutes {

}

#seconds {

}

JavaScript

// set minutes
var mins = 1;
var down = true;
// calculate the seconds (don't change this! unless time progresses at a                 different speed for you...)
var secs = mins * 60;
var timeout;
var doispontos = ":";

function countdown() {
    timeout = setTimeout(Decrement, 1000);
}


function colorchange(minutes, seconds,colon) {
    if (minutes.value == "00" && seconds.value == "59") {
        minutes.style.color = "orange";
        seconds.style.color = "orange";
        colon.style.color = "orange";
        doispontos = "orange";

    } else if (minutes.value == "00" && seconds.value == "30") {
        minutes.style.color = "red";
        seconds.style.color = "red";
        colon.style.color = "orange";
        doispontos = "red";
    }

}

function Decrement() {
    if (document.getElementById) {
        minutes = document.getElementById("minutes");
        seconds = document.getElementById("seconds");
         colon = document.getElementById("colon");
        // if less than a minute remaining

        if (seconds < 59) {
            seconds.value = secs;

        } else {
            minutes.value = getminutes();
            seconds.value = getseconds();
        }
        colorchange(minutes, seconds,colon);

        secs--;
        if (secs < 0) {
            secs--;
            clearTimeout(timeout);
            return;
        }
        countdown();
    }
}

function getminutes() {
    // minutes is seconds divided by 60, rounded down
    mins = Math.floor(secs / 60);
    return ("0" + mins).substr(-2);
}

function getseconds() {
    // take mins remaining (as seconds) away from total seconds remaining
    return ("0" + (secs - Math.round(mins * 60))).substr(-2);
}



countdown();