/* F3 challenge (amber) */
.f3-track{position:relative;}
.f3-line{position:absolute;left:19px;top:10px;bottom:10px;width:2px;background:var(--line);}
.f3-step{display:grid;grid-template-columns:40px 1fr;gap:20px;padding:14px 0;position:relative;}
.f3-dot{width:40px;height:40px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:800;font-size:14px;z-index:1;background:var(--brand-tint);color:var(--brand);border:2px solid var(--brand);}
.f3-step h3{font-size:17px;font-weight:800;margin:6px 0 3px;display:flex;align-items:center;gap:10px;}
.f3-tag{font-size:10.5px;font-weight:700;text-transform:uppercase;letter-spacing:.4px;padding:3px 9px;border-radius:999px;background:#e7f7ee;color:var(--green);}
.f3-step p{font-size:14px;color:var(--body);margin:0;max-width:640px;}
.f3-step.stuck .f3-dot{background:var(--amber-tint);color:var(--amber);border-color:#e5a24d;}
.f3-step.stuck .f3-tag{background:var(--amber-tint);color:#b8690f;}
.f3-break{margin-left:60px;background:var(--amber-tint);border:1px solid var(--amber-line);border-radius:12px;padding:16px 20px;font-size:14px;color:#8a5a1a;margin-top:8px;max-width:760px;}
.f3-break b{color:#7a4d10;}
.chal-grid{display:grid;grid-template-columns:1.12fr .88fr;gap:26px 44px;align-items:start;grid-template-areas:"head viz" "steps viz";}
.chal-head{grid-area:head;}
.chal-grid .f3-track{grid-area:steps;}
.chal-grid .chal-viz{grid-area:viz;align-self:center;}
.chal-viz{background:#fff;border:1px solid var(--line);border-radius:18px;padding:24px;box-shadow:var(--shadow);}
.chal-viz .vh{font-size:11px;font-weight:700;letter-spacing:.5px;text-transform:uppercase;color:var(--muted);margin-bottom:4px;}
.chal-viz .vt{font-size:16px;font-weight:800;color:var(--ink);margin-bottom:16px;letter-spacing:-.01em;}
.chal-chart{width:100%;height:auto;display:block;}
.xlab{display:flex;justify-content:space-between;font-size:11px;font-weight:600;color:var(--muted);margin-top:2px;padding:0 6px;}
.chal-legend{display:flex;flex-wrap:wrap;gap:16px;margin-top:16px;padding-top:15px;border-top:1px solid var(--line);font-size:12px;color:var(--body);}
.chal-legend .lg{display:inline-flex;align-items:center;gap:7px;}
.chal-legend .sw{width:18px;height:3px;background:var(--brand);border-radius:2px;flex:0 0 18px;}
.chal-legend .sw.dash{background:none;border-top:2.5px dashed var(--brand);height:0;opacity:.7;}
.chal-legend .sw.band{height:12px;background:#fbe9d2;border:1px solid var(--amber-line);border-radius:3px;}
/* momentum chart animation — traveling dot (plays once on scroll; static fallback) */
.chal-chart .gapArea{opacity:.7;}
.chal-chart .potential{opacity:.6;}
.chal-chart .traveler{opacity:0;filter:drop-shadow(0 0 5px rgba(19,81,216,.55));transition:opacity .35s ease;}
@keyframes chDraw{to{stroke-dashoffset:0;}}
@keyframes chGap{from{opacity:0;}to{opacity:.7;}}
@keyframes chPot{from{opacity:0;}to{opacity:.6;}}
@keyframes chDot{from{opacity:0;}to{opacity:1;}}
.chal-chart.anim-ready .journey{stroke-dasharray:1;stroke-dashoffset:1;}
.chal-chart.anim-ready .gapArea,.chal-chart.anim-ready .potential,.chal-chart.anim-ready .cdot{opacity:0;}
.chal-chart.play .journey{animation:chDraw 1.35s cubic-bezier(.6,0,.2,1) .15s forwards;}
.chal-chart.play .gapArea{animation:chGap .5s ease 1.2s forwards;}
.chal-chart.play .potential{animation:chPot .5s ease 1.25s forwards;}
.chal-chart.play .cdot{animation:chDot .45s ease forwards;}
.chal-chart.play .d-start{animation-delay:.25s;} .chal-chart.play .d-demo{animation-delay:.75s;}
.chal-chart.play .d-pot{animation-delay:1.35s;} .chal-chart.play .d-stall{animation-delay:1.3s;}
.chal-chart.travel-on .traveler{opacity:1;}
@media(max-width:900px){ .chal-grid{grid-template-columns:1fr;grid-template-areas:"head" "viz" "steps";} }