body {
    font-family: sans-serif;
    text-align: center;
    margin: 25px auto;
    padding: 0;
    max-width: 600px;
}
p {
    text-align: justify;
}
canvas {
    border: 1px solid #444;
    margin-top: 10px;
}
.controls {
    margin-top: 10px;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}
.controls button {
    margin: 4px 4px;
}
.led {
    display: inline-block;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: #777;
    margin: 0 6px;
    vertical-align: middle;
    box-shadow: inset 0 0 2px rgba(0, 0, 0, 0.5);
}
.led.on {
    background: #28c840;
    box-shadow: 0 0 6px rgba(40, 200, 64, 0.8);
}
.controls button:disabled {
    opacity: 0.6;
}
.controls input[type="range"] {
    width: 200px;
}
/* Frequency control table */
.freq-table {
    margin: 10px auto;
    border-collapse: collapse;
}
.freq-table td {
    padding: 2px 5px;
}
.freq-table td:first-child {
    text-align: right;
    white-space: nowrap;
}
.freq-table td:last-child {
    font-family: monospace;
    text-align: left;
    white-space: pre;
}
/* Instant custom tooltip */
[data-tooltip] {
    position: relative;
}
[data-tooltip]::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: calc(100% + 4px);
    left: 50%;
    transform: translateX(-50%);
    background: #333;
    color: #fff;
    font-size: 11px;
    font-weight: normal;
    white-space: nowrap;
    padding: 3px 7px;
    border-radius: 4px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0s;
}
[data-tooltip]:hover::after,
[data-tooltip]:focus::after {
    opacity: 1;
}

#info {
    margin-top: 10px;
    font-family: monospace;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.meter {
    display: flex;
    align-items: center;
    margin: 4px 0;
}
.meter span {
    width: 30px;
    text-align: right;
    margin-right: 5px;
}
.bar {
    flex: 1;
    height: 12px;
    background: #ddd;
    margin: 0 5px;
    position: relative;
}
.fill {
    background: green;
    height: 100%;
    width: 0%;
    transition: background 0.2s;
}
.fill.disabled {
    background: #bbb !important;
}
.mic-fill {
    background: #e07820;
}