.notebook .problem-catalog.problem-page { max-width: 1020px; margin-inline: auto; padding: 0; }
.problem-catalog::after { content: none !important; }
.problem-catalog .crumbs { margin: 0 0 22px; font-size: 14px; }
.problem-catalog .crumbs a { display: inline-flex; align-items: center; gap: 7px; min-height: 44px; text-decoration: none; }
.problem-workspace { display: grid; grid-template-columns: minmax(0,760px) 184px; gap: 48px; align-items: start; }
.problem-catalog .problem { min-width: 0; margin: 0; padding: 0; border: 0; background: none; box-shadow: none; }
.problem-catalog .problem h1 { margin: 5px 0 20px; color: var(--pen); font: 600 38px/1.16 Caveat,cursive; }
.task-meta { display: flex; flex-wrap: wrap; gap: 4px 16px; color: var(--muted); font: 400 13px/21px 'IBM Plex Sans',sans-serif; }
.problem-catalog .task-statement { margin: 0 0 32px; }
.problem-catalog .task-statement p { margin: 0 0 18px; }
.problem-catalog .problem-marginalia { padding-top: 14px; }
.problem-catalog .browse-nav { position: relative; top: auto; right: auto; width: 100%; margin: 0 0 50px; }
.problem-catalog .browse-link { font-weight: 500; padding: 7px 4px; }
.problem-catalog .problem-marginalia > details { margin-top: 10px; background: #fff; font: 400 13px/21px 'IBM Plex Sans',sans-serif; }
.problem-marginalia > details > summary { position: relative; display: flex; align-items: center; gap: 8px; min-height: 44px; padding: 8px 10px; background: #fff; font-weight: 500; list-style: none; cursor: pointer; }
.problem-marginalia > details > summary::before { content: ''; position: absolute; left: 0; top: 9px; bottom: 9px; width: 3px; background: var(--pen); clip-path: polygon(12% 0,100% 4%,79% 100%,0 94%); }
.problem-marginalia > details > summary::after { content: '›'; margin-left: auto; font-size: 20px; }
.problem-marginalia > details[open] > summary::after { transform: rotate(90deg); }
.problem-marginalia > details[open] { padding-bottom: 12px; }
.problem-marginalia > details > :not(summary) { margin: 12px 10px 0; }
.task-facts { display: grid; gap: 6px; }
.task-facts div { display: flex; align-items: baseline; justify-content: space-between; gap: 8px; }
.task-facts dd { margin: 0; font-weight: 600; }
.problem-catalog .source { border: 0; padding: 0; margin: 12px 0 0; font-size: 12px; }
.task-help-actions { display: grid; gap: 4px; }
.task-help-actions a { display: flex; align-items: center; gap: 7px; min-height: 44px; color: var(--ink); text-decoration: none; }
.problem-catalog :is(.crumbs a,.task-help-actions a,.browse-history a):hover { background: linear-gradient(transparent 35%,#f3dc6266 35%,#f3dc6266 78%,transparent 78%); }
.problem-catalog summary:focus-visible,.problem-catalog a:focus-visible { outline: 0; background: none; box-shadow: 0 3px var(--pen); }
.problem-catalog .answer { max-width: 540px; margin: 30px 0 0; }
.problem-catalog .answer-heading { display: flex; align-items: center; justify-content: space-between; gap: 20px; margin-bottom: 14px; }
.problem-catalog .answer-heading > label,.problem-catalog .answer-choices > legend { font: 600 24px/28px Caveat,cursive; }
.problem-catalog .answer-format { position: relative; font: 400 13px/21px 'IBM Plex Sans',sans-serif; }
.problem-catalog .answer-format summary { display: grid; place-items: center; width: 44px; height: 40px; list-style: none; cursor: pointer; }
.problem-catalog .answer-format p { position: absolute; right: 0; z-index: 3; width: min(290px,calc(100vw - 48px)); margin: 0; padding: 14px; background: #fff; box-shadow: 0 4px 14px #24344224; }
.problem-catalog .answer .row { align-items: end; justify-content: flex-start; gap: 28px; }
.problem-catalog .answer .field { flex: 0 1 210px; min-height: 48px; padding-bottom: 5px; }
.problem-catalog .answer .field input { min-width: 0; min-height: 42px; padding-inline: 2px; font: 20px/28px Literata,serif; }
.problem-catalog .answer .field > span { font: 18px/28px Literata,serif; white-space: nowrap; padding: 0 5px; }
.answer-attempts { display: flex; align-items: center; gap: 13px; margin-top: 18px; color: var(--muted); font: 400 13px/22px 'IBM Plex Sans',sans-serif; }
.answer-attempts > span:last-child { display: flex; gap: 12px; }
.answer-attempts i { width: 8px; height: 20px; background: var(--pen); clip-path: polygon(65% 0,95% 0,30% 100%,0 100%); }
.answer-attempts i.used { opacity: .3; }
.answer-feedback { min-height: 0; margin: 12px 0 0; font: 400 14px/22px 'IBM Plex Sans',sans-serif; }
.answer-feedback:empty { display: none; }
.answer-reveal { margin-top: 20px; font: 400 13px/21px 'IBM Plex Sans',sans-serif; }
.answer-reveal > summary { display: inline-flex; align-items: center; min-height: 44px; cursor: pointer; list-style: none; }
.answer-reveal > summary::after { content: '›'; margin-left: 9px; }
.answer-reveal p { margin: 4px 0; }
.answer-choices { display: grid; gap: 6px; margin: 0 0 14px; padding: 0; border: 0; }
.problem-catalog .verdict { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 12px; padding: 0; }
.problem-catalog .verdict > span { flex-basis: 100%; color: var(--ink); font-size: 15px; }
.problem-catalog .solution { border: 0; padding: 0; margin-top: 24px; background: none; }
.problem-catalog .solution > summary { display: inline-flex; align-items: center; gap: 7px; min-height: 44px; font-size: 14px; cursor: pointer; }
.problem-catalog .solution .text { padding-top: 10px; }
.problem-catalog .contribution { margin-top: 32px; border: 0; padding: 18px 0 0; background: var(--pen-stroke) top center / 100% 7px no-repeat; }
.problem-catalog .contribution h2 { margin-bottom: 18px; }
.problem-catalog .contribution textarea { min-height: 150px; }
.browse-history { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin: -8px 0 20px; }
.browse-history a { display: inline-flex; align-items: center; justify-content: center; min-width: 44px; min-height: 40px; padding: 4px 6px; font-size: 13px; text-decoration: none; }
.browse-history a[aria-current=step] { color: var(--pen); font-weight: 600; }
.browse-history a[aria-current=step]::before { content: ''; width: 3px; height: 24px; margin-right: 6px; background: var(--pen); transform: rotate(5deg); }
.problem-task-stage { position: relative; overflow: hidden; }
.problem-task-ghost { position: absolute; top: 0; left: 0; width: 100%; pointer-events: none; }
.problem-catalog[aria-busy=true] { cursor: progress; }
@media (width < 1100px) {
  .problem-workspace { grid-template-columns: minmax(0,1fr); gap: 12px; }
  .problem-catalog .problem-marginalia { display: contents; }
  .problem-workspace > .problem { grid-row: 2; }
  .problem-catalog .browse-nav { grid-row: 1; width: min(420px,100%); margin: 0 0 10px; }
  .problem-marginalia > details { max-width: 540px; }
}
@media (width < 640px) {
  .problem-catalog .problem h1 { font-size: 32px; }
  .problem-catalog .answer .row { gap: 16px; flex-wrap: wrap; }
  .problem-catalog .answer .field { flex-basis: 160px; }
  .problem-catalog .answer .btn { font-size: 14px; padding-inline: 14px; }
}
@media (prefers-reduced-motion: reduce) { .problem-task-ghost { display: none; } }