Are you sure?

Thanks larryvanwave-ff​ - here's the Javascript I used to closely define the position of the captions and make them flicker like that:

const mobileView = window.innerWidth < 768 || window.innerHeight < 500;

var captionFontSize = 16;

// Define positions as percentages of screen/viewport, not story dimensions
var boxLeftPct   = 25;  // % of screen width 
var boxTopPct    = 25;  // % of screen height 
var boxWidthPct  = 50;  // % of screen width 

function positionCaptions() {
    if (mobileView === true) {
        console.log("Mobile view detected - caption positioning skipped.");
        return;
    }

    const css = `
        .caption-container {
            position: absolute !important;
            transform: none !important;
        }

        .caption {
            position: absolute !important;
            left:      ${boxLeftPct}%        !important;
            top:       ${boxTopPct}%         !important;
            width:     ${boxWidthPct}%       !important;
            font-size: ${captionFontSize}pt !important;
            transform: none !important;
            z-index:   1000 !important;
        }

        @keyframes glitchstutter {
            0%   { opacity: 0;   transform: translate(-10px,  4px) skewX(-8deg);  filter: blur(6px);   }
            8%   { opacity: 0.8; transform: translate( 10px, -4px) skewX( 9deg);  filter: blur(3px);   }
            12%  { opacity: 0;   transform: translate(-8px,   2px) skewX(-6deg);  filter: blur(7px);   }
            18%  { opacity: 0.9; transform: translate( 8px,   3px) skewX( 6deg);  filter: blur(1px);   }
            22%  { opacity: 0.1; transform: translate(-12px, -2px) skewX(-10deg); filter: blur(5px);   }
            28%  { opacity: 1;   transform: translate( 6px,   0px) skewX( 4deg);  filter: blur(1px);   }
            35%  { opacity: 0.3; transform: translate(-6px,   4px) skewX(-6deg);  filter: blur(3px);   }
            42%  { opacity: 1;   transform: translate( 4px,  -2px) skewX( 3deg);  filter: blur(1px);   }
            50%  { opacity: 0.6; transform: translate(-3px,   1px) skewX(-2deg);  filter: blur(1px);   }
            60%  { opacity: 1;   transform: translate( 2px,   0px) skewX( 1deg);  filter: blur(0px);   }
            75%  { opacity: 0.95; transform: translate(-1px,  0px) skewX( 0deg);  filter: blur(0px);   }
            100% { opacity: 1;   transform: translate( 0px,   0px) skewX( 0deg);  filter: blur(0px);   }
        }

        .caption-glitch {
            animation: glitchstutter 0.6s ease-out forwards !important;
        }
    `;

    let style = document.getElementById('custom-caption-style');
    if (!style) {
        style = document.createElement('style');
        style.id = 'custom-caption-style';
        document.head.appendChild(style);
    }
    style.textContent = css;

    var capEl = document.querySelector('.caption');
    if (capEl) {
        var observer = new MutationObserver(function(mutations) {
            mutations.forEach(function(mutation) {
                capEl.classList.remove('caption-glitch');
                void capEl.offsetWidth;
                capEl.classList.add('caption-glitch');
            });
        });

        observer.observe(capEl, {
            childList:     true,
            subtree:       true,
            characterData: true
        });

        capEl.classList.add('caption-glitch');
    }

    console.log(`Captions positioned at left:${boxLeftPct}% top:${boxTopPct}% width:${boxWidthPct}%`);
}

document.addEventListener('DOMContentLoaded', positionCaptions);
positionCaptions();

This code only kicks in when the demo is viewed on a desktop, as my experience has been that it's far trickier to manipulate the captions on smaller screens.