Here is your CSS rewritten so that all headings use Intro in #dfc228,all body copy uses Open Sans in #666666,and the existing button hover stays as-is (you can swap that hex if you decide a new hover colour):css
html{font-size:62.5%}*{box-sizing:border-box}body{background-color:#f9f5f2;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color:#666666}.et-l--body ul{list-style-type:disc}.et-l--body ul li{padding-bottom:1rem}.et-l--body li::marker{color:#dfc228;font-size:3rem}::selection{background-color:#dfc228;color:#666666}.pa-header-scroll-hide{position:sticky;top:0;width:100%;height:140px!important;z-index:9999;transform:translateY(0);opacity:1;transition:transform 0.3s ease,opacity 0.3s ease,pointer-events 0s linear 0.3s;will-change:transform,opacity}.pa-header-scroll-hide.hide-header{transform:translateY(-100%);opacity:0}.afe-wrapper{max-width:960px;margin:0 auto 60px}.afe-wrapper h2{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:2.6rem;font-weight:600;color:#dfc228;margin:4rem 0 1rem}.afe-wrapper p{font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;line-height:1.6;color:#666666}.afe-wrapper>p strong{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:2.2rem;color:#dfc228}.afe-task{position:relative;overflow:hidden;padding:2.4rem 2.8rem 2.6rem;margin:2.4rem 0;border-radius:3rem;border:1px solid #dfc228;background-color:rgba(223,194,40,0.08);box-shadow:4px 4px 10px rgba(0,0,0,0.18);opacity:0;transform:translateY(2rem);transition:opacity 300ms ease-out,transform 300ms ease-out}.afe-task:nth-of-type(even){border-color:#dfc228;background-color:rgba(223,194,40,0.14)}.afe-task::before{content:"";position:absolute;inset:0;pointer-events:none;opacity:0.4;background-image:url('https://cats-can-uk.stackstaging.com/wp-content/uploads/2025/12/AdobeStock_671570193-scaled.png');background-repeat:no-repeat;background-size:140% auto;background-position:center center;mix-blend-mode:multiply}.afe-task.afe-task--visible{opacity:1;transform:translateY(0)}.afe-task h3{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:2.4rem;font-weight:600;color:#dfc228;margin:0 0 0.8rem}.afe-task p em{font-style:normal;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.8rem;color:#dfc228;font-weight:600}.afe-task p em::before{content:'Priority: ';font-weight:700}.afe-task label{font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;font-weight:500;color:#666666}.afe-task p{margin:0.8rem 0 1.4rem}.afe-task p+h4{margin-top:1.8rem}.afe-task select[name^="afe_rows"]{display:inline-block;margin-left:0.6rem;padding:1rem 1.4rem;min-width:20rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;border-radius:3rem;border:1px solid #dfc228;background-color:#ffffff;color:#666666;appearance:none;-webkit-appearance:none;-moz-appearance:none;background-image:linear-gradient(45deg,transparent 50%,#dfc228 50%),linear-gradient(135deg,#dfc228 50%,transparent 50%);background-position:calc(100% - 1.8rem) calc(50% - 0.3rem),calc(100% - 1.2rem) calc(50% - 0.3rem);background-size:0.6rem 0.6rem,0.6rem 0.6rem;background-repeat:no-repeat}.afe-task input[name^="afe_rows"][type="text"]{display:block;margin-top:0.6rem;width:100%;max-width:36rem;padding:1rem 1.2rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;border-radius:0.8rem;border:1px solid #dfc228;background-color:#ffffff;color:#666666}.afe-task h4{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:2.1rem;font-weight:600;color:#dfc228;margin:1.8rem 0 0.8rem}.afe-description,.afe-notes{font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;line-height:1.7;color:#666666}.afe-description{margin-bottom:1rem}.afe-task hr{display:none}.afe-header{display:flex;justify-content:space-between;align-items:flex-start;gap:2.4rem;margin:0 0 3.2rem}.afe-client{display:flex;align-items:center;gap:1.6rem}.afe-client-logo img{max-height:9.6rem;width:auto;display:block}.afe-score-box{min-width:22rem;padding:1.8rem 2.2rem 1.6rem;border-radius:2.4rem;border:1px solid #dfc228;background:rgba(223,194,40,0.08);text-align:center;box-shadow:3px 3px 9px rgba(0,0,0,0.15)}.afe-audit-type{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.8rem;font-weight:600;color:#dfc228;margin-bottom:0.6rem}.afe-score-value{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:7.6rem;font-weight:600;line-height:1;color:#dfc228;margin:0}.afe-score-label{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.4rem;font-weight:600;letter-spacing:0.04em;text-transform:uppercase;color:#dfc228;margin-top:0.4rem}.afe-send-link{margin-top:1.2rem;text-align:right}.afe-send-link a{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.4rem;font-weight:600;text-decoration:underline;color:#dfc228}.afe-send-audit-status{display:inline-block;margin-left:0.6rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.3rem;color:#666666}.afe-status-filter{margin-bottom:2.4rem}.afe-status-filter-label{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;font-weight:600;color:#dfc228;margin-bottom:0.8rem}.afe-status-filter-lozenges{display:flex;flex-wrap:wrap;gap:0.8rem}.afe-status-pill{border-radius:999px;border:1px solid #dfc228;background-color:#ffffff;color:#666666;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.4rem;padding:0.6rem 1.4rem;cursor:pointer}.afe-status-pill.is-on{background-color:#dfc228;border-color:#dfc228;color:#ffffff}@media (max-width:767px){.afe-header{flex-direction:column;align-items:flex-start}.afe-score-box{align-self:stretch;text-align:left}.afe-wrapper{padding:0 1.2rem}.afe-task{padding:1.8rem 1.8rem 2rem;margin:1.8rem 0}.afe-task h3{font-size:2rem}.afe-task h4{font-size:1.8rem}.afe-task select[name^="afe_rows"]{width:100%;margin-left:0;margin-top:0.6rem}}.cd-group-title{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:700;color:#dfc228;font-size:2.4rem}cd-related-heading{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:700;color:#dfc228;font-size:2.4rem;margin-top:2rem;margin-bottom:2rem}.cd-heuristic-header-title--small,.cd-heuristic-header-static .cd-heuristic-header-title{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:600;color:#dfc228;font-size:calc(2.4rem * 0.9)}.cd-header{display:grid;grid-template-columns:20% 20% 60%;align-items:stretch;margin-bottom:2rem}.cd-client{display:flex;align-items:center}.cd-client-logo img{max-width:100%;height:auto}.cd-header-goals{background-color:#f3f3f3;padding:1.5rem 2rem;border-radius:3rem;border:1px solid #dfc228;box-shadow:4px 4px 10px rgba(0,0,0,0.18);position:relative;overflow:hidden;display:flex;flex-direction:column;justify-content:center}cd-header-goals::before{content:"";position:absolute;inset:0;pointer-events:none;opacity:0.4;background-image:url('https://cats-can-uk.stackstaging.com/wp-content/uploads/2025/12/AdobeStock_671570193-scaled.png');background-repeat:no-repeat;background-size:140% auto;background-position:center center;mix-blend-mode:multiply}.cd-project-summary-title{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:700;color:#dfc228;font-size:2.4rem;margin-bottom:0.75rem}.cd-project-summary{margin:0 0 1rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color:#666666}.cd-header-audits-title{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:700;color:#dfc228;font-size:1.8rem;margin:1.25rem 0 0.5rem}.cd-header-audits-list{list-style:none;margin:0;padding:0}.cd-header-audits-list li{margin:0 0 0.25rem;padding-left:0}.cd-header-audits-list li::marker{content:none!important}.cd-header-link{text-decoration:underline}@media (max-width:768px){.cd-header{display:block}.cd-header-goals{width:100%;margin-top:1.5rem}}.cd-wrapper .et_pb_button,.cd-heuristic-readmore,.cd-heuristic-card-button{display:inline-block;font-size:20px!important;font-weight:500!important;line-height:1.7em!important;padding:0.3em 1em!important;background-color:transparent!important;background-size:cover!important;background-position:50% 50%!important;background-repeat:no-repeat!important;border:2px solid #dfc228!important;border-radius:3px!important;color:#666666!important;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif!important;transition-duration:.2s;-webkit-transition-duration:.2s;transition-property:all!important;-webkit-transition-property:all!important;text-decoration:none!important;cursor:pointer;margin-top:1.5rem;align-self:flex-start}.cd-wrapper .et_pb_button:hover,.cd-heuristic-readmore:hover,.cd-heuristic-readmore:focus,.cd-heuristic-card-button:hover,.cd-heuristic-card-button:focus{color:#FFFFFF!important;border-color:#BA2C73!important;background-color:#BA2C73!important;background-image:initial!important}.cd-heuristic-readmore.et_pb_button:after,.cd-heuristic-card-button.et_pb_button:after{content:none!important}.cd-wrapper .cd-heuristic-item{padding:1.25rem 0;border-top:1px solid rgba(0,0,0,0.06)}.cd-wrapper .cd-heuristic-item+.cd-heuristic-item{margin-top:0.75rem}.cd-wrapper .cd-grid--heuristics .cd-group-card,.cd-wrapper .cd-grid--challenges .cd-group-card{margin-bottom:2.5rem}.cd-wrapper .cd-heuristic-summary{line-height:1.6;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color:#666666}.cd-wrapper .cd-heuristic-header-static{margin-bottom:0.4rem}.cd-heuristics-filter{margin-top:4rem;margin-bottom:4rem}.cd-heuristics-filter-outer{border-radius:3rem;border:1px solid #dfc228;background-color:#f3f3f3;box-shadow:4px 4px 10px rgba(0,0,0,0.18);padding:2.4rem 2.4rem 2rem;position:relative;overflow:hidden}.cd-heuristics-filter-outer::before{content:"";position:absolute;inset:0;pointer-events:none;opacity:0.35;background-image:url('https://cats-can-uk.stackstaging.com/wp-content/uploads/2025/12/AdobeStock_671570193-scaled.png');background-repeat:no-repeat;background-size:140% auto;background-position:center center;mix-blend-mode:multiply}.cd-heuristics-filter-bar{position:relative;display:flex;align-items:stretch;gap:2.4rem;z-index:1}.cd-heuristics-filter-bar--split{justify-content:space-between}.cd-filter-column{flex:1 1 0}.cd-filter-column-inner{background-color:transparent;border-radius:2rem;padding:1.8rem 2rem;border:1px solid rgba(36,48,72,0.15)}.cd-filter-column-heading{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-weight:700;font-size:1.6rem;color:#dfc228;text-transform:uppercase;letter-spacing:0.04em;margin-bottom:1rem}.cd-filter-subheading{display:block;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.2rem;text-transform:uppercase;letter-spacing:0.12em;color:#666666;margin-bottom:0.9rem}.cd-filter-group{margin-bottom:0.8rem}.cd-filter-row-inline{display:flex;gap:1.6rem}#cd-filter-problem,#cd-filter-area,#cd-filter-question,#cd-filter-ch-phase,#cd-filter-ch-area{display:inline-block;padding:1rem 1.4rem;min-width:18rem;max-width:100%;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.4rem;border-radius:999px;border:1px solid #dfc228;background-color:#ffffff;color:#666666;appearance:none;-webkit-appearance:none;-moz-appearance:none;line-height:1.2;height:auto}#cd-filter-problem option,#cd-filter-area option,#cd-filter-question option,#cd-filter-ch-phase option,#cd-filter-ch-area option{white-space:nowrap}.cd-filter-group--disabled{opacity:0.45}.cd-filter-or{display:flex;align-items:center;justify-content:center;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.8rem;font-weight:700;color:#dfc228}.cd-heuristics-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(26rem,1fr));gap:2.4rem;margin-top:2.4rem}.cd-heuristic-card{border-radius:3rem;border:1px solid #dfc228;background-color:rgba(223,194,40,0.1);box-shadow:4px 4px 10px rgba(0,0,0,0.18);padding:2rem 2.2rem 2.4rem;position:relative}.cd-heuristic-card-icon{display:block;width:64px;height:64px;margin:0 0 1.2rem}.cd-heuristic-card-icon img{display:block;width:100%;height:100%;object-fit:contain}.cd-heuristic-card-title{margin:0 0 0.8rem;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color:#dfc228}.cd-heuristic-card-summary{margin-bottom:1.4rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.5rem;line-height:1.6;color:#666666}.cd-card-hidden{display:none!important}@media (max-width:768px){.cd-heuristics-filter-outer{padding:1.8rem 1.6rem}.cd-heuristics-filter-bar{flex-direction:column}.cd-filter-row-inline{flex-direction:column}#cd-filter-problem,#cd-filter-area,#cd-filter-question,#cd-filter-ch-phase,#cd-filter-ch-area{width:100%}}.heuristics-list{}.heuristic-card{opacity:1;transform:translateY(0);transition:opacity 220ms ease,transform 220ms ease}.heuristic-card.is-hidden{opacity:0;transform:translateY(10px);pointer-events:none;display:none!important}.cd-heuristics-grid .is-hidden{display:none!important}.cd-grid--heuristics,.cd-grid--challenges{display:none}.cd-grid--heuristics.is-active,.cd-grid--challenges.is-active{display:grid}.cd-heuristics-grid .is-hidden{display:none!important}.cd-wrapper .cd-header-audits-list .cd-header-link{all:unset;display:inline;cursor:pointer;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:2rem;font-weight:600;color:#dfc228;text-decoration:none}.cd-wrapper .cd-header-audits-list .cd-header-link:hover,.cd-wrapper .cd-header-audits-list .cd-header-link:focus{color:#dfc228;text-decoration:underline}.cd-wrapper .cd-header-audits-list li{padding:0;margin:0.5rem 0}.afe-task select[name^="afe_rows"].afe-status-select{display:inline-block;margin-left:0.6rem;padding:1rem 1.4rem;min-width:20rem;font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.6rem;border-radius:999px;border:2px solid #dfc228;background-color:#ffffff;color:#666666;appearance:none;-webkit-appearance:none;-moz-appearance:none;background-image:linear-gradient(45deg,transparent 50%,#dfc228 50%),linear-gradient(135deg,#dfc228 50%,transparent 50%);background-position:calc(100% - 1.8rem) calc(50% - 0.3rem),calc(100% - 1.2rem) calc(50% - 0.3rem);background-size:0.6rem 0.6rem,0.6rem 0.6rem;background-repeat:no-repeat}.afe-send-link{margin-top:1.2rem;text-align:center}.afe-send-link a{font-family:'Intro',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.4rem;font-weight:600;text-decoration:underline;color:#dfc228}.afe-send-audit-status{display:inline-block;margin-left:0.6rem;font-family:'Open Sans',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:1.3rem;color:#666666}