/* IPO: three columns joined by chalk arrows */
.ipo { display: grid; grid-template-columns: 1fr 90px 1fr 90px 1fr; align-items: stretch; margin-top: 30px; }
.stage-col { border-top: 6px solid var(--line-2); padding-top: 22px; }
.stage-col.hot { border-top-color: var(--accent); }
.stage-col h3 { font-size: 44px; margin: 10px 0 8px; }
.stage-col p { color: var(--chalk); }
.stage-col ul { list-style: none; margin-top: 14px; }
.stage-col li { font-size: 23px; padding: 8px 0; border-bottom: 1px solid var(--line); color: var(--chalk-2); }
.arrow { position: relative; }
.arrow::before { content: ''; position: absolute; left: 14px; right: 18px; top: 70px; height: 3px; background: var(--chalk-2); }
.arrow::after { content: ''; position: absolute; right: 12px; top: 62px; border: 9px solid transparent; border-left: 14px solid var(--chalk-2); }
.store { margin-top: 46px; padding: 20px 0; border-top: 1px dashed var(--line-2); border-bottom: 1px dashed var(--line-2); font-size: 26px; color: var(--chalk-2); }
.store strong { color: var(--chalk); margin-right: 8px; }

.ins-head { position: absolute; left: 96px; top: 92px; z-index: 2; pointer-events: none; }

/* machine cycle ring */
.cycle { display: grid; grid-template-columns: 560px 1fr; gap: 80px; align-items: center; margin-top: 10px; }
.ring { position: relative; width: 520px; height: 520px; border: 2px dashed var(--line-2); border-radius: 50%; }
.ring button { position: absolute; width: 190px; padding: 16px 0; text-align: center; background: var(--board); border: 1px solid var(--line-2); font-family: var(--head); font-weight: 800; font-size: 28px; color: var(--chalk-2); transform: translate(-50%, -50%); transition: background .3s, color .3s, border-color .3s; }
.ring button b { display: block; font: 700 15px/1 var(--mono); color: var(--chalk-3); margin-bottom: 6px; }
.ring button.on { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.ring button.on b { color: var(--accent-ink); }
.ring button[data-k="0"] { left: 50%; top: 0; } .ring button[data-k="1"] { left: 100%; top: 50%; }
.ring button[data-k="2"] { left: 50%; top: 100%; } .ring button[data-k="3"] { left: 0; top: 50%; }
.ring .hub { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); width: 150px; height: 150px; border: 2px solid var(--accent); display: grid; place-items: center; font-size: 30px; font-weight: 700; color: var(--chalk); }
.explain { position: relative; min-height: 300px; }
.explain .ex { position: absolute; inset: 0; opacity: 0; transition: opacity .3s; }
.explain .ex.on { opacity: 1; }
.explain h3 { font-size: 52px; margin-bottom: 16px; color: var(--accent); }
.explain p { font-size: 30px; color: var(--chalk); max-width: 640px; }
.explain p.mono { font-size: 32px !important; margin-top: 24px; }

/* memory hierarchy: stacked bars, widest at the bottom */
.hier { display: flex; flex-direction: column; align-items: center; gap: 16px; margin-top: 30px; }
.tier { width: var(--w); min-width: 300px; display: grid; grid-template-columns: 1fr auto; gap: 2px 18px; padding: 24px 28px; background: var(--board-3); border-left: 6px solid var(--accent); }
.tier b { font-family: var(--head); font-weight: 800; font-size: 30px; color: var(--chalk); }
.tier .sz { font-style: normal; font: 700 22px/1.4 var(--mono); color: var(--accent); text-align: right; }
.tier i { font-style: normal; font-size: 20px; color: var(--chalk-3); grid-column: 1 / -1; }
.tier:nth-child(1) { opacity: 1; } .tier:nth-child(2) { border-left-color: color-mix(in srgb, var(--accent) 80%, var(--board)); }
.tier:nth-child(3) { border-left-color: color-mix(in srgb, var(--accent) 60%, var(--board)); } .tier:nth-child(4) { border-left-color: color-mix(in srgb, var(--accent) 40%, var(--board)); }
.axis { display: flex; justify-content: space-between; margin-top: 22px; font-size: 18px; color: var(--chalk-3); }
html[data-lang="si"] .stage-col h3 { font-size: 40px; }
html[data-lang="si"] .explain h3 { font-size: 46px; }
html[data-lang="si"] .ring button { font-size: 25px; }
.cycle { margin-top: 64px; grid-template-columns: 500px 1fr; }
.ring { width: 440px; height: 440px; margin-left: 40px; }
.ring button { width: 200px; }