Right-sized packaging

<div class="right"><div class="pair"><div><strong>SMALL</strong><div class="cells" id="small"></div><b>400 g · $5</b></div><div><strong>LARGE</strong><div class="cells" id="large"></div><b>800 g · $8</b></div></div><label>WEEKLY USE <b id="use">300 g</b><input id="weekly" type="range" min="200" max="800" step="100" value="300"></label><p id="waste">SMALL: 100 g left · LARGE: 500 g left</p></div>

.right{width:min(92%,560px);font:900 clamp(10px,max(1.9vmin,1vw),14px)/1.2 sans-serif}.pair{display:flex;gap:8px}.pair>div{flex:1;background:var(--surface);border:2px solid var(--line);padding:clamp(7px,2vmin,14px)}.pair strong{display:block}.pair b{display:block;margin-top:6px;color:var(--muted)}.cells{display:flex;gap:3px;margin-top:7px;height:clamp(38px,12vmin,70px)}.cells i{flex:1;background:var(--accent);transition:.3s}.cells i.left{background:var(--line)}label{display:block;margin-top:clamp(10px,3vmin,20px)}label b{float:right;color:var(--accent)}input{display:block;width:100%;accent-color:var(--accent)}p{margin:6px 0 0;background:var(--accent-2);color:#211b19;padding:6px;text-align:center}@media(min-width:700px){body>:first-child{transform:scale(1.25);transform-origin:center}}

document.querySelector('#small').innerHTML='<i></i>'.repeat(4);document.querySelector('#large').innerHTML='<i></i>'.repeat(8);const r=document.querySelector('#weekly');function draw(){const use=+r.value;document.querySelector('#use').textContent=use+' g';for(const [id,n] of [['small',4],['large',8]])document.querySelectorAll('#'+id+' i').forEach((e,i)=>e.classList.toggle('left',i>=Math.min(n,use/100)));document.querySelector('#waste').textContent='SMALL: '+Math.max(0,400-use)+' g left · LARGE: '+Math.max(0,800-use)+' g left'}r.oninput=draw;draw();setTimeout(()=>{r.value=700;draw()},650);setTimeout(()=>{r.value=300;draw()},2600);