style.css

body {
    display: flex;
    flex-flow: column wrap;
    align-items: center;
    height: 99%; /*making these 100% makes scroll bar visible*/
    width: 99%;
}

.xxLarge {
    font-size: 3rem;
    border-radius: 5%;
}

#CALC {
    width: 80%;
    min-width: 330px;
    max-width: 500px;
    padding: 1.5rem 1rem 1.5rem 1rem;
    border: 5px solid black;
    border-radius: 10%;
    display: flex;
    flex-flow: column wrap;
    align-items: center;
}

#ROW1 {
    width: 100%;
    display: flex;
    flex-flow: column wrap;
    justify-content: flex-start;
    align-items: center;
}

#TITLE_TEXT {
    margin: 0rem 1rem 0rem 1rem;
    padding: 0;
    text-align: center;
    color: orange;
    font-size: x-large;
}

#EQN_TEXT {
    width: 90%;
    padding: 0.2em 0.2em;
    text-align: center;
    border: 4px solid black;
    border-radius: 5000px;
}

#ANS_DIV {
    border: 2px solid black;
    width: 90%;
    height: 2.5em;
    margin-bottom: 1em;
    border-radius: 5000px;

    display: flex;
    flex-flow: row nowrap;
    justify-content: space-between;
}

#ANS_TEXT {
    padding: 0em 0em;
    margin: 0.2em 0.5em;
    color: darkgreen;
    font-size: 1.5em;
}

#ANS_TEXT.active {
    animation-name: animationAns;
    animation-duration: 200ms;
}

@keyframes animationAns {
    from {
        margin-left: 50%;
    }
}

#COPY_BTN {
    cursor: pointer;
    border-radius: 5000px;
    border: 1px solid gray;
    background-color: rgb(251, 251, 231);
}
#COPY_BTN:hover {
    background-color: rgb(238, 238, 211);
}
#COPY_BTN:active {
    background-color: rgb(238, 238, 211);
    /*box-shadow: 0px 0px 5px 2px orange;*/
}
#COPY_BTN > img {
    height: 1.5em;
    width: 1.5em;
    padding: 2px 2px;
}
@keyframes copyHighlight {
    from {
        box-shadow: 0px 0px 5px 10px orange;
    }
}

table {
    width: 90%;
    border: table;
    /*background-color: gainsboro;*/
}

td {
    margin: 0;
    padding: 0;
}

table button {
    cursor: pointer;
    margin: 0em 0em;
    font-size: 2rem;
    font-weight: bold;
    width: 100%;
    min-height: 4rem;
    border: 0;
    border-radius: 15%;
    background-color: beige;
    /*
    border: 3px solid grey;
    */
}

table button:hover {
    background-color: orange;
}

table button:active {
    background-color: darkorange;
}

#INFO {
    width: 80%;
    min-width: 330px;
    max-width: 500px;
    padding: 0.5rem 2rem;
}

#TOGGLEDIV {
    width: 80%;
    min-width: 330px;
    max-width: 500px;
    padding: 0.5rem 2rem;
    display: flex;
    flex-flow: row nowrap;
}

#QSTMARK {
    cursor: pointer;
    font-size: 0.9em;
    background-color: antiquewhite;
    border: 1px solid black;
    padding: 5px;
    border-radius: 30%;
}

@keyframes highlight {
    0% {
        font-size: 0.9em;
        background-color: antiquewhite;
        box-shadow: 0px 0px 0px orange;
    }

    50% {
        font-size: 1.3em;
        background-color: orange;
        box-shadow: 0px 0px 20px orange;
    }

    100% {
        font-size: 0.9em;
        background-color: antiquewhite;
        box-shadow: 0px 0px 0px orange;
    }
}

@media (max-width: 600px) {
    #CALC {
        width: 100%;
        height: 100%;
    }

    #TOGGLEDIV {
        width: 100%;
        height: 100%;
    }

    #INFO {
        width: 100%;
        height: 100%;
    }
}