/* Chapter 1: the exposure triangle */

.exposure-intro{padding-bottom:48px}
.exposure-intro p{max-width:68ch;margin:0 0 16px;font-size:clamp(18px,2vw,22px);line-height:1.55}
.exposure-intro p:last-child{margin-bottom:0}
.exposure-foundation>p,.exposure-balance>p{max-width:70ch}
.stop-rules{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;max-width:750px;margin:25px 0}
.stop-rules p{display:flex;flex-direction:column;gap:5px;margin:0;padding:18px 20px;background:var(--paper-2);border-left:4px solid var(--amber)}
.stop-rules strong{font:800 25px var(--sans);color:var(--ink)}
.stop-rules span{font:500 15px/1.4 var(--sans);color:var(--muted)}
.exposure-foundation table{max-width:900px;margin-top:24px}
.pillar-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
.pillar-grid article{padding:24px;background:var(--paper-2);border-top:4px solid var(--amber)}
.pillar-number{font:800 12px var(--sans);letter-spacing:.13em;color:var(--muted)}
.pillar-grid h3{margin:10px 0 17px}
.pillar-grid p{margin:0 0 14px}
.pillar-grid p:last-child{margin-bottom:0}
.balance-options{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;margin:28px 0}
.balance-options article{padding:20px;border:1.5px solid var(--rule)}
.balance-options strong{display:block;margin-bottom:10px;font:800 18px var(--sans)}
.balance-options p{margin:0}
.exposure-balance .btn{margin-top:18px}

/* Playground layout */
.play{display:grid;grid-template-columns:minmax(0,1.45fr) minmax(0,1fr);gap:40px;align-items:start;padding-bottom:64px}
.vf-col{position:sticky;top:calc(var(--header-h) + 20px)}

/* Viewfinder */
.frame{position:relative;aspect-ratio:16/10;border-radius:8px;overflow:hidden;background:#000}
#scene{display:block;width:100%;height:100%;transition:filter .12s linear}
.af{position:absolute;inset:0;pointer-events:none}
.af i{position:absolute;width:22px;height:22px;border:2px solid #ffffffb0}
.af i:nth-child(1){top:14px;left:14px;border-right:0;border-bottom:0}
.af i:nth-child(2){top:14px;right:14px;border-left:0;border-bottom:0}
.af i:nth-child(3){bottom:14px;left:14px;border-right:0;border-top:0}
.af i:nth-child(4){bottom:14px;right:14px;border-left:0;border-top:0}
.af b{position:absolute;left:56.5%;top:52%;width:34px;height:34px;margin:-17px 0 0 -17px;border:2px solid var(--amber);border-radius:3px;opacity:.9}
.readout{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:14px 8px 4px;font-family:var(--sans);color:var(--amber);font-variant-numeric:tabular-nums}
.vals{display:flex;gap:18px;font-size:22px;font-weight:700;font-stretch:80%;white-space:nowrap}
.vals small{font-size:13px;font-weight:500;opacity:.75;margin-right:2px}
.meter{flex:1;max-width:330px;min-width:180px}
.meter-scale{position:relative;height:16px}
.meter-scale span{position:absolute;bottom:0;width:1.5px;height:6px;background:var(--amber-dim);transform:translateX(-50%)}
.meter-scale span.full{height:11px;background:var(--amber)}
.meter-nums{position:relative;height:16px;font-size:12px;font-weight:600;color:var(--amber)}
.meter-nums span{position:absolute;transform:translateX(-50%)}
.needle{position:absolute;top:-4px;width:0;height:0;border-left:6px solid transparent;border-right:6px solid transparent;border-top:8px solid var(--lcd);transform:translateX(-50%);transition:left .15s ease-out}
.needle.out{animation:blink .7s steps(2) infinite}
@keyframes blink{50%{opacity:.15}}
.effects dd{font-size:16px}

/* Exposure total and sliders with 1/3-stop tick marks */
.total{padding-bottom:22px;border-bottom:1px solid var(--rule)}
.total .big{font-family:var(--sans);font-stretch:70%;font-weight:800;font-size:64px;line-height:1;letter-spacing:-.01em;font-variant-numeric:tabular-nums}
.total .light{font-family:var(--sans);font-size:20px;font-weight:600;margin:6px 0 4px}
.total p{margin:0;color:var(--muted);font-size:17px;min-height:1.6em}
.slider{position:relative;height:44px;margin-top:6px}
.slider input{position:absolute;inset:0;margin:0}
.ticks{position:absolute;left:12px;right:12px;top:24px;height:12px}
.ticks span{position:absolute;top:0;width:1.5px;height:6px;background:var(--rule);transform:translateX(-50%)}
.ticks span.full{height:12px;background:var(--muted)}
.ends{display:flex;justify-content:space-between;font-family:var(--sans);font-size:13px;color:var(--muted);margin-top:2px}

/* Example presets */
.presets{padding-top:22px}
.presets h3{font-size:17px;margin:0 0 12px}
.preset-row{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.preset{font:inherit;color:inherit;text-align:left;background:transparent;border:1.5px solid var(--rule);border-radius:12px;padding:8px;cursor:pointer}
.preset:hover{border-color:var(--ink)}
.preset[aria-pressed="true"]{border-color:var(--ink);background:var(--paper-2)}
.thumb{height:46px;border-radius:6px;background:linear-gradient(#6FA3C9,#B9D3E0 58%,#4F5E44 58%)}
.preset strong{display:block;font-family:var(--sans);font-size:15px;margin-top:8px}
.preset span{display:block;font-family:var(--sans);font-size:13px;color:var(--muted);font-variant-numeric:tabular-nums}

/* One-stop comparison */
td.base{font-weight:700;background:var(--paper-2);padding-left:10px}
th.base{padding-left:10px}
.path{display:block;color:var(--muted);font-size:14px;margin-top:2px}

/* Why f-stops have strange numbers */
.fstops{--max:112px;padding-bottom:88px}
.irises{display:grid;grid-template-columns:repeat(10,minmax(0,1fr));align-items:end;gap:8px;padding:28px 24px 20px;background:var(--body);border-radius:22px;margin-bottom:44px}
.irises figure{margin:0;display:flex;flex-direction:column;align-items:center;gap:12px}
.irises i{display:block;width:calc(var(--max) / var(--n));aspect-ratio:1;border-radius:50%;background:radial-gradient(circle at 35% 30%,#FFF4D6,var(--amber) 70%);box-shadow:0 0 0 1.5px #ffffff26}
.irises figcaption{font-family:var(--sans);font-weight:700;font-stretch:80%;font-size:17px;color:var(--amber);font-variant-numeric:tabular-nums}
.fs-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:40px 56px;align-items:start}
/* f-numbers: the long explanation on the left, the two short ones stacked on the right */
.fstops .fs-grid>:first-child{grid-row:span 2}
/* thirds: two explanations side by side, the aperture sequence full width below */
.thirds .fs-grid>:last-child{grid-column:1/-1}
.fs-grid p{margin:0 0 12px}
.direction dl{margin:0 0 16px}
.direction dl div{display:flex;justify-content:space-between;gap:12px;padding:10px 0;border-bottom:1px solid var(--rule);font-family:var(--sans)}
.direction dt{font-weight:600}
.direction dd{margin:0;font-weight:700;font-variant-numeric:tabular-nums}

/* Modern cameras click in thirds */
.thirds{padding-bottom:88px}
.dials{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:0;background:var(--body);border-radius:22px;padding:8px 0;margin-bottom:44px}
.dial{padding:20px 24px 22px;font-family:var(--sans);color:var(--on-body)}
.dial+.dial{border-left:1px solid var(--on-body-rule)}
.dial h3{font-size:17px;margin:0 0 18px}
.clicks{display:grid;grid-template-columns:repeat(4,1fr);list-style:none;margin:0;padding:0;position:relative}
.clicks::before{content:"";position:absolute;left:12.5%;right:12.5%;top:0;height:1.5px;background:var(--amber-dim)}
.clicks li{position:relative;text-align:center;padding-top:18px;font-size:17px;font-weight:600;color:#C9CDD0;font-variant-numeric:tabular-nums;white-space:nowrap}
.clicks li::before{content:"";position:absolute;left:50%;top:-4px;width:2px;height:10px;background:var(--amber-dim);transform:translateX(-50%)}
.clicks li.full{color:var(--amber);font-weight:800;font-size:20px;font-stretch:85%}
.clicks li.full::before{top:-8px;height:18px;background:var(--amber)}
.dial p{margin:16px 0 0;font-size:14px;color:var(--on-body-muted);text-align:center}
.seq{display:flex;flex-wrap:wrap;gap:8px;list-style:none;margin:8px 0 0;padding:0;font-family:var(--sans);font-variant-numeric:tabular-nums}
.seq li{padding:6px 11px;border-radius:999px;border:1.5px solid var(--rule);font-size:16px;font-weight:600;color:var(--muted)}
.seq li.full{border-color:var(--ink);color:var(--ink);font-weight:800}
.seq-key{margin-top:12px!important;font-family:var(--sans);font-size:14px;color:var(--muted)}
.eq-steps{margin:0 0 12px;padding:0;list-style:none}
.eq-steps li{font-family:var(--serif);font-size:22px;padding:4px 0 4px 16px;border-left:3px solid var(--amber);font-variant-numeric:lining-nums}
.eq-steps li+li{margin-top:6px}
.eq-steps b{font-family:var(--sans);font-weight:800}

@media (max-width:900px){
  .play{grid-template-columns:1fr;gap:28px;padding-bottom:48px}
  .vf-col{position:static}
  .pillar-grid,.balance-options{grid-template-columns:1fr}
  .fs-grid{grid-template-columns:1fr;gap:32px}
  .fstops .fs-grid>:first-child{grid-row:auto}
  .dials{grid-template-columns:1fr;padding:0}
  .dial+.dial{border-left:0;border-top:1px solid var(--on-body-rule)}
}
/* Keep the viewfinder in view while the sliders are dragged, when the screen is tall enough */
@media (max-width:900px) and (min-height:620px){
  .vf-col{display:contents}
  .viewfinder{position:sticky;top:calc(var(--header-h) + 12px);z-index:10;box-shadow:0 0 0 12px var(--paper),0 18px 24px -18px #0009}
  .effects{margin-top:-10px}
}
@media (max-width:560px){
  .stop-rules{grid-template-columns:1fr}
  .exposure-foundation table{font-size:14px}
  .exposure-foundation th,.exposure-foundation td{padding-right:6px}
  .frame{aspect-ratio:16/9}
  .readout{flex-direction:column;align-items:stretch;gap:8px;padding-top:10px}
  .vals{justify-content:space-between;font-size:20px}
  .meter{max-width:none}
  .total .big{font-size:52px}
  .preset-row{gap:8px}
  .dials{border-radius:16px}
  .dial{padding:18px 16px 20px}
  .eq-steps li{font-size:19px}
  .fstops{--max:58px}
  .irises{grid-template-columns:repeat(5,minmax(0,1fr));row-gap:22px;padding:22px 12px 16px;border-radius:16px}
  .irises figcaption{font-size:15px}
}