/* R7.3.2 Explore by Problem: /problems and problem pages. Loaded only there, after cases.css.
   Single-column editorial rows on the 3/12 + 9/12 grid, no cards. Brass only on numbers and on the hover line;
   small brass labels use --brass-ink (cases.css) for contrast in the light theme. */

/* index */
.pb-index-head .lead{max-width:56ch}
.pb-index{padding-top:0}
.pb-grid{display:grid;grid-template-columns:minmax(0,3fr) minmax(0,9fr);gap:20px clamp(24px,4vw,64px);align-items:start}
.pb-l .cs-h span{color:var(--brass-ink)}
.pb-list{border-bottom:1px solid var(--line)}
.pb-list li a{position:relative;display:grid;grid-template-columns:3rem 28px minmax(0,1fr);column-gap:16px;padding:26px 0 28px;border-top:1px solid var(--line);text-decoration:none;color:inherit}
.pb-list li a::before{content:"";position:absolute;left:0;top:-1px;height:1px;width:100%;background:var(--brass-ink);transform:scaleX(0);transform-origin:left;transition:transform .18s var(--ease)}
.pb-list li a:hover::before,.pb-list li a:focus-visible::before{transform:scaleX(1)}
.pb-n{font-family:var(--mono);font-size:.8rem;letter-spacing:.06em;color:var(--brass-ink);padding-top:6px}
.pb-ic{color:var(--muted);margin-top:3px}
.pb-body{display:flex;flex-direction:column;min-width:0}
.pb-t{font-size:clamp(1.3rem,2vw,1.6rem);font-weight:600;letter-spacing:-.015em;line-height:1.2}
.pb-s{color:var(--muted);font-size:1rem;line-height:1.5;margin-top:8px;max-width:64ch}
.pb-dq{margin-top:14px;font-size:.98rem;line-height:1.45;max-width:64ch}
.pb-dk{display:inline-block;font-family:var(--mono);font-size:.68rem;letter-spacing:.14em;text-transform:uppercase;color:var(--dim);margin-right:12px}
.pb-c{font-family:var(--mono);font-size:.7rem;letter-spacing:.04em;color:var(--dim);margin-top:12px}
.pb-list li a:hover .pb-t{text-decoration:underline;text-underline-offset:5px;text-decoration-thickness:1px;text-decoration-color:var(--brass-ink)}
@media (prefers-reduced-motion:reduce){.pb-list li a::before{transition:none}}

/* problem page: header */
.pb-eyebrow{gap:10px}
.pb-eyebrow .pb-ic{color:var(--muted);margin:0}
.pb-eyebrow .cs-no{font-family:var(--mono);color:var(--brass-ink)}
.pb-head h1{max-width:22ch}
.pb-statement{max-width:60ch;margin-bottom:clamp(26px,3vw,40px)}
.pb-intent{max-width:60ch;color:var(--muted);margin:0}
.pb-intent .cs-label{color:var(--dim);margin-bottom:8px}

/* path strip: Knowledge -> Decision Lab -> Experience -> Evidence */
.pb-path{padding-bottom:clamp(24px,3vw,40px)}
.pb-path ol{display:flex;flex-wrap:wrap;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.pb-path li{position:relative;flex:1 1 0}
.pb-path li + li::before{content:"";position:absolute;left:0;top:50%;width:14px;height:1px;background:var(--line-2);transform:translateX(-50%)}
.pb-path a{display:flex;align-items:baseline;justify-content:space-between;gap:12px;padding:16px clamp(14px,2vw,24px);text-decoration:none;color:inherit;border-left:1px solid var(--line);transition:background-color .18s}
.pb-path li:first-child a{border-left:0;padding-left:0}
.pb-path a:hover{background:var(--hover)}
.pb-path li:first-child a:hover{background:none}
.pp-t{font-family:var(--mono);font-size:.72rem;letter-spacing:.12em;text-transform:uppercase;color:var(--muted)}
.pp-n{font-family:var(--mono);font-size:1.1rem;color:var(--brass-ink)}
@media (prefers-reduced-motion:reduce){.pb-path a{transition:none}}

/* modules */
.pb-impact{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:18px clamp(20px,3vw,40px)}
.pb-impact li{border-left:1px solid var(--line-2);padding-left:16px}
.pb-impact strong{display:block;font-family:var(--mono);font-size:.72rem;font-weight:500;letter-spacing:.1em;text-transform:uppercase;margin-bottom:6px}
.pb-impact span{display:block;color:var(--muted);font-size:.94rem;line-height:1.45}
.pb-from{margin:14px 0 0;font-size:.88rem;color:var(--muted)}
.pb-from span,.pb-also > span,.pk-k{font-family:var(--mono);font-size:.64rem;letter-spacing:.12em;text-transform:uppercase;color:var(--dim);margin-right:10px}
.pb-from a,.pb-also a,.pr-list a,.ev-list .ev-from a{text-underline-offset:3px;text-decoration-color:var(--brass-ink)}
.pb-from .pb-more{font-family:var(--sans);font-size:.88rem;letter-spacing:0;text-transform:none;color:var(--dim);margin-left:10px}
.pk-list,.pl-list,.pc-list{border-bottom:1px solid var(--line)}
.pk-list a,.pl-list a,.pc-list a{display:flex;flex-direction:column;gap:6px;padding:18px 0 20px;border-top:1px solid var(--line);text-decoration:none;color:inherit}
.pk-d{font-family:var(--mono);font-size:.68rem;letter-spacing:.08em;color:var(--dim)}
.pk-t,.pl-t,.pc-t{font-size:1.14rem;font-weight:600;line-height:1.3}
.pk-r,.pl-q,.pc-q{color:var(--muted);font-size:.95rem;line-height:1.5;max-width:66ch}
.pk-k{display:block;margin:2px 0 4px}
.pl-go{font-family:var(--mono);font-size:.68rem;letter-spacing:.1em;text-transform:uppercase;color:var(--brass-ink);margin-top:6px}
.pl-list li{border-top:1px solid var(--line)}
.pl-list li a{border-top:0}
.pl-c{margin:-10px 0 0;padding-bottom:18px;font-family:var(--mono);font-size:.68rem;letter-spacing:.04em;color:var(--dim)}
.pc-list .cls{margin:0}
.pk-list a:hover .pk-t,.pl-list a:hover .pl-t,.pc-list a:hover .pc-t{text-decoration:underline;text-underline-offset:4px;text-decoration-color:var(--brass-ink)}
.pb-sub{font-family:var(--mono);font-size:.68rem;letter-spacing:.14em;text-transform:uppercase;color:var(--dim);margin:28px 0 0;padding-bottom:4px}
.pc-list.is-supporting .pc-t{font-size:1.02rem}
.pb-also{display:flex;flex-wrap:wrap;align-items:baseline;gap:6px 18px;margin:16px 0 0;font-size:.94rem}
.pb-also > span{margin-right:0}
.pb-h3{font-family:var(--mono);font-size:.7rem;font-weight:400;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);margin:0 0 14px}
.pb-h3:not(:first-child){margin-top:34px}
.pr-list li{display:flex;flex-wrap:wrap;gap:4px 14px;align-items:baseline;padding:12px 0;border-top:1px solid var(--line)}
.pr-list li:last-child{border-bottom:1px solid var(--line)}
.pr-list > li > a{font-weight:600}
.pr-via{color:var(--muted);font-size:.9rem}

/* related problems */
.pb-related{padding:clamp(32px,4vw,56px) 0 0}
.pb-related ul{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));column-gap:clamp(24px,4vw,56px);border-bottom:1px solid var(--line)}
.pb-related a{display:flex;gap:14px;align-items:baseline;padding:14px 0;border-top:1px solid var(--line);text-decoration:none;font-weight:600}
.pb-related a:hover{text-decoration:underline;text-underline-offset:4px;text-decoration-color:var(--brass-ink)}
.pb-related .pb-n{padding:0;font-weight:400}
.problem-page .case-nav{grid-template-columns:1fr auto 1fr}

@media (max-width:980px){
  .pb-grid{grid-template-columns:1fr;gap:10px}
}
.pb-sub:first-child{margin-top:0}