* {
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    line-height: 1rem;
}

html, body {
    font-size: 26px;
    font-family: system-ui, sans-serif;
    overflow: hidden;
    background-color: #222;
    color: #fff;
}

body {
    max-width: 600px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

strong { font-weight: 600; }
small { font-size: 0.7em; }

mark {
    min-width: 3rem;
    padding: 0.1rem 0.5rem;
    margin-top: -0.05rem;
    background-color: rgba(0, 200, 0, 0.5);
    color: inherit;
    text-align: center;
    font-variant-numeric: tabular-nums;
}

section { display: block; }
section + section { margin-top: 1.5rem; }

.level { position: relative; }
.level > mark { position: absolute; left: 5rem; }
.level > small { position: absolute; left: 8.25rem; }

button {
    font: inherit;
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 0.25rem;
    background-color: #1a701a;
    color: #fff;
    font-weight: 500;
    cursor: pointer;
}
button + button { margin-left: 0.5rem; }
button#stop { background-color: #c00; }
button:disabled { background-color: #aaa !important; color: #ddd; }

#buttons { text-align: center; }

input[type="range"] {
    display: block;
    margin-top: 0.5rem;
    width: 100%;
    appearance: none;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 0.125rem;
}

input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 1rem;
    height: 1rem;
    border-radius: 50%;
    background-color: #1a701a;
}