main {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    user-select: none;
}

.white { background-color: white; color: #555 }
.black { background-color: black; color: #aaa }

.radio {
    display: none;
}
.radio:checked + label {
    flex: 0;
}

.pause {
    background-color: #aaa;
    color: #555;
    overflow: hidden;
    flex: 0;
    min-height: 32px;
    display: flex;
    justify-content: center;
    align-items: center;
    border-top: 1px solid black;
    border-bottom: 1px solid white;
}
.pause-label {
    position: absolute;
    opacity: 1;
    transition: opacity .2s;
}
.pause-label:first-of-type {
    left: 12px;
}
.pause-label:last-of-type {
    right: 12px;
    transform: rotate(180deg);
}
.radio:checked + .pause .pause-label {
    opacity: 0;
}

.time {
    flex: 1;
    display: flex;
    justify-content: center;
    align-content: center;
    padding: 32px 12px 48px;
    font-size: 400%;
    transition: flex .2s;
    border-bottom: 16px solid;
    animation: 1s linear infinite alternate blink;
    position: relative;
}
.time.white {
    transform: rotate(180deg);
    border-color: black;
}
.time.black {
    border-color: white;
}
.time:not(.timeup) {
    border-color: transparent;
}
.total.clock, .count {
    position: absolute;
    bottom: 4px;
    font-size: 50%;
    opacity: 50%;
}
.count       { left:  24px }
.total.clock { right: 24px }

@keyframes blink {
      0% { border-color: transparent }
     45% { border-color: transparent }
}

.settings {
    flex-direction: column;
    justify-content: center;
    align-items: center;
    display: none;
    opacity: 0;
    transition: opacity .2s;
}
.radio:checked + .pause {
    flex: 1;
}
.radio:checked + .pause .settings {
    display: flex;
    opacity: 1;
}
.settings div {
    display: flex;
}
.settings input {
    border: none;
    font-size: 110%;
    width: 8em;
    max-width: 100%;
    text-align: center;
    padding: .5em 1em;
    box-sizing: border-box;
}
.settings .white { color: black }
.settings .black { color: white }
.settings button {
    background-color: #555;
    color: white;
    border: none;
    padding: 1em;
    box-sizing: border-box;
    width: 100%;
}