Performance budget

<div class="atlas"><div class="head"><b>PERFORMANCE BUDGET · page weight</b><span class="pulse"></span></div><div class="stage"><div class="pb-top"><b id="pb-total">410 KB</b><span>budget 500 KB</span></div><div class="pb-track"><i class="pb-base"></i><i id="pb-image"></i><strong class="pb-limit"></strong></div><div class="pb-key"><span>base 250 KB</span><span id="pb-img-label">images 160 KB</span></div><button class="pb-state box" id="pb-state">within budget</button></div></div>

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let phase=0;const images=[160,310,120];function show(n){phase=n;const size=images[n],over=250+size>500;document.getElementById('pb-image').style.width=Math.round(size/700*100)+'%';document.getElementById('pb-total').textContent=250+size+' KB';document.getElementById('pb-img-label').textContent='images '+size+' KB';document.getElementById('pb-state').textContent=over?'over budget — tap to optimize':'within budget — tap to add image';document.getElementById('pb-state').classList.toggle('over',over)}show(0);setInterval(()=>show((phase+1)%3),1500);document.getElementById('pb-state').onclick=()=>show((phase+1)%3)