div#left {
    float: left;
}
#problem-generator {
    box-shadow: #ddd 0px 0px 10px;
    border-radius: 10px;
    padding: 0px 10px;
    display: table;
    margin: 0 auto 10px;
    transition: 0.3s all;
	user-select: none;
}
#problem-generator:hover {
    box-shadow: #adf 0px 0px 10px;
}
#problem-generator label {
    margin: 10px;
    display: inline-block;
}
#problem-generator input, #problem-generator select {
    display: inline-block;
    min-width: 100px;
    vertical-align: middle;
}
#problem-generator output {
    float: right;
    font-weight: bold;
    font-size: 80%;
    opacity: 0.8;
    color: #00C;
}
#probs {
    display: flex;
    flex-wrap: wrap;
}
#timerContainer {
    opacity: 0;
}
#timerContainer.running:hover,
#timerContainer.show {
    opacity: 0.75;
}
/* problem # */
.prob::before {
    margin: -10px;
    content: attr(data-q) ".";
    float: left;
    opacity: .25;
    font-size: 70%;
    text-shadow: -1px -1px 1px #fff;
}
.prob:hover {
    background-color: #def;
}
.prob {
    text-align: right;
    border: 10px solid rgb(255, 255, 255);
    border-radius: 25px;
    background-color: rgb(238, 238, 238);
    padding: 20px;
    width: 20%;
    box-sizing: border-box;
    font-size: 20pt;
    line-height: initial;
    min-width: 125px;
    transition: 0.3s all;
    opacity: 0;
}
.prob:focus-within {
    box-shadow: 0 0 5px #666 inset;
}
.prob input {
    font-size: 25pt;
    text-align: right;
    width: 100%;
    box-sizing: border-box;
    margin-top: 5px;
    transition: 0.3s ease all;
}
.correct {
    background-color: lightgreen;
}
.main   {
    overflow: hidden;
}

@media print {
    #problem-generator {
        display: none;
    }
}
@media only screen and (max-width: 600px) {
    .prob {
        width: 50%;
    }
}