* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
}

body {
    font-family: Arial, sans-serif;
    background-color: #1a1a2e;
    color: #e0e0e0;
    overflow: hidden;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}

#stage {
    height: 100vh;
    height: 100dvh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 16px 16px 40px;
    text-align: center;
}

/* Grid: numbers (and arrow) on row 1, instructions under each number on row 2 */
#display {
    display: grid;
    grid-template-columns: 1fr;
    width: 100%;
    color: #ffffff;
}

#display .num,
#display .arrow {
    font-weight: bold;
    font-variant-numeric: tabular-nums;
    line-height: 1;
    white-space: nowrap;
    font-size: min(55vw, 70vh);
    grid-row: 1;
}

#display .instruction {
    grid-row: 2;
    margin-top: 16px;
    font-size: 1.2em;
    color: #777;
    min-height: 1.4em;
    line-height: 1.3;
}

#to-num, #to-instruction { grid-column: 1; }

/* Hidden unless transitioning */
#from-num, #from-instruction, #display .arrow { display: none; }

#display.transitioning {
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
}

#display.transitioning .num,
#display.transitioning .arrow {
    font-size: min(22vw, 40vh);
}

#display.transitioning #from-num,
#display.transitioning #from-instruction,
#display.transitioning .arrow { display: block; }

#display.transitioning #from-num,
#display.transitioning #from-instruction { grid-column: 1; }

#display.transitioning .arrow { grid-column: 2; padding: 0 0.15em; }

#display.transitioning #to-num,
#display.transitioning #to-instruction { grid-column: 3; }

#progress-track {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    height: 24px;
    background-color: rgba(255, 255, 255, 0.06);
}

#progress-bar {
    height: 100%;
    width: 0;
    background-color: #4fc3f7;
}

#status {
    position: fixed;
    top: 8px;
    right: 12px;
    font-size: 0.75em;
    color: #555;
}

#status.error {
    color: #e57373;
}