/* ---------- Tetris specific ---------- */
html, body {
    margin: 0;
    padding: 0;
    height: 100vh;
    overflow: hidden;
    background: #fff;
    color: #111;
    font-family: Arial, Helvetica, sans-serif;
}

/* canvas – playing field */
#gameCanvas {
    display: block;
    margin: 0 auto;
    background: #ffffff;
    border: 2px solid #00ffff;
}

/* score – right‑top corner */
#score {
    position: absolute;
    top: 10px;
    right: 20px;
    font-size: 20px;
    z-index: 10;
}

/* overlay (start screen, settings, messages) */
.overlay,
.overlayMessage {
    position: absolute;
    inset: 0;
    background: #fff;
    color: rgba(0, 0, 0, 0.86);
    display: none;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    z-index: 20;
    top: 220px;
}

.overlay button,
.overlay input[type="radio"] + label {
    margin: 12px;
    font-size: 18px;
    padding: 8px 16px;
    cursor: pointer;
}

/* button style */
.overlay button {
    background: #333;
    border: 1px solid #555;
    color: #fff;
}
.overlay button:hover {
    background: #444;
}

/* radios */
.overlay input[type="radio"] {
    margin-right: 5px;
}

/* messages – big centered text */
.overlayMessage {
    font-size: 48px;
    font-weight: bold;
}

/* fade‑in animation for speed‑up */
@keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}
.overlayMessage[style*="display: flex"] {
    animation: fadein 0.2s;
}