RGB Stopwatch using HTML, CSS and JavaScript

By Shuvranil Mondal

Responsive without using any framework, RGB color animation with Pause, Play, Reset button.

Screenshot:

Description:

- Apply css animation.

- Apply css media query to make it responsive.

JavaScript code:

let result = document.getElementById('result')
hr = 0
min = 0
sec = 0

disSEC = 0
disMIN = 0
disHR = 0

let strBTN = ()=>{
    let start = document.getElementById('start')
    myVar = setInterval(()=>{
        sec++
        if(sec==60){
            sec = 0
            min++
        }
        if(min==60){
            min = 0
            hr++
        }
        if(sec < 10){
            disSEC = '0' + sec.toString()
        }else{
            disSEC = sec
        }
        if(min < 10){
            disMIN = '0' + min.toString()
        }else{
            disMIN = min
        }
        if(hr < 10){
            disHR = '0' + hr.toString()
        }else{
            disHR = hr
        }
        result.innerHTML = `${disHR}:${disMIN}:${disSEC}`
        
    },1000)
    
}

let rstBTN =()=>{
    hr = 0
    min = 0
    sec = 0
    clearTimeout(myVar)
    result.innerHTML = `0${hr}:0${min}:0${sec}`
}

CSS code:

*{
    margin: 0;
    padding: 0;
    box-sizing:border-box ;
}
html{
    font-family: Arial, Helvetica, sans-serif;
    font-size: 62.5%;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    background: black;
}

.display{
    width: 400px;
    height: 100px;
    border: 10px solid red;
    position: relative;
    border-radius: 10px;
    animation: RGB 4s ease infinite forwards;
    box-shadow: rgb(255 0 0 / 36%) 1px 17px 65px 19px, rgb(255 0 0 / 37%) 0px 0px 44px 6px;
}

.display #result{
    position: absolute;
    transform: translate(-50%,-50%);
    top: 50%;
    left: 50%;
    font-size: 5rem;
    color: red;
    animation: txt 4s ease infinite forwards;
}

@keyframes txt{
    0%{color: red;
            
    }
    25%{color: green;
        
    }
    50%{color: blue;
        
    }
    75%{color: yellow;
        
    }
}

.btn{
    display: inline-block;
    text-decoration: none;
    padding-top: 0.4em;
    padding-bottom: 0.4em;
    color: white;
    height: 100%;
    width: 100%;
    text-align: center;
    font-size: 2rem;
    text-transform: uppercase;
    z-index: 999;
    user-select: none;
    -webkit-tap-highlight-color:  rgba(255, 255, 255, 0);
}


.main-box{
    position: relative;
    display: inline-block;
    height: 41px;
    width: 119px;
    border: 3px solid red;
    animation: rgb 4s ease infinite forwards;
    margin-top: 50px;
    border-radius: 10px;
}
.mid-box{
    margin-left: 10px;
    margin-right: 10px;
}
.box{
    position: absolute;
    height: 100%;
    width: 100%;
    z-index: 2;
    opacity: 1;
}



.btn:focus{
    color: gray;
}



@keyframes rgb{
    0%{border-color: red;
            
    }
    25%{border-color: green;
        
    }
    50%{border-color: blue;
        
    }
    75%{border-color: yellow;
        
    }
}

@keyframes RGB{
    0%{border-color: red;
        box-shadow: rgb(255 0 0 / 36%) 1px 17px 65px 19px, rgb(255 0 0 / 37%) 0px 0px 44px 6px;
    }
    25%{border-color: green;
        box-shadow: rgba(0, 128, 0, 0.438) 1px 17px 65px 19px, rgba(0, 128, 0, 0.5) 0px 0px 44px 6px;
    }
    50%{border-color: blue;
        box-shadow: rgba(0, 0, 255, 0.438) 1px 17px 65px 19px, rgba(0, 0, 255, 0.438) 0px 0px 44px 6px;
    }
    75%{border-color: yellow;
        box-shadow: rgba(255, 255, 0, 0.459) 1px 17px 65px 19px, rgba(255, 255, 0, 0.459) 0px 0px 44px 6px;
    }
}

@media (max-width:500px){
    html{
        font-size: 50%;
        
    }
    .display{
        width: 200px;
        height: 100px;
    }
    .contenor{
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%,-50%);
    }
    .main-box{
        display: inline-block;
        margin-top: 20px;
    }
    .btn{
        padding-top: 0.6em;
        cursor: pointer;
        -webkit-tap-highlight-color:  rgba(255, 255, 255, 0); 
    }
}