/* Shared mechanics for the /testing/ design studies D–G.
   Layout skeletons and interaction states only. Every colour, face, rule and
   texture is set by the design's own stylesheet through the tokens below. */
:root{--ink:#111;--paper:#fff;--muted:#666;--line:#ccc;--accent:#c00;--surface:#fff;--display:serif;--body:sans-serif;--mono:monospace;--wrap:1240px;--pad:clamp(20px,5vw,72px);--r:0}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:24px}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--body);font-size:16px;line-height:1.65;-webkit-font-smoothing:antialiased}
img,svg{max-width:100%;display:block}
figure{margin:0}
p{margin:0 0 1.15em}
h1,h2,h3,h4{margin:0;font-family:var(--display);font-weight:500;line-height:1.1;text-wrap:pretty}
a{color:inherit}
button,input,select,textarea{font:inherit;color:inherit}
button,select{cursor:pointer}
button{background:none;border:0;padding:0}
ul,ol{padding-left:1.3em;margin:0 0 1.15em}
li{margin-bottom:.5em}
li p{margin:0}
dd{margin:0}
dl{margin:0}
table{border-collapse:collapse;width:100%}
th,td{text-align:left;vertical-align:top}
[hidden]{display:none!important}
:focus-visible{outline:3px solid var(--accent);outline-offset:4px}
.skip{position:absolute;top:-100px;left:16px;z-index:99;background:var(--ink);color:var(--paper);padding:8px 12px}
.skip:focus{top:8px}
.small,.note{font-size:13px;line-height:1.55;color:var(--muted)}
.wrap{max-width:var(--wrap);margin:0 auto;padding-inline:var(--pad)}
.measure{max-width:66ch}
.sample-label{display:block;font-size:10.5px;letter-spacing:.09em;text-transform:uppercase;color:var(--muted);margin-bottom:14px;line-height:1.5}
.preview-bar{display:flex;justify-content:space-between;gap:16px;padding:9px var(--pad);font-size:11.5px;letter-spacing:.02em}
.preview-bar a{text-decoration:none}
.hp{position:absolute;left:-10000px;width:1px;height:1px;overflow:hidden}

/* Header and navigation */
.site-header{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:20px var(--pad)}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font-family:var(--display);white-space:nowrap}
.brand svg{width:32px;height:36px;fill:none;stroke:currentColor;stroke-width:1.4}
.site-header nav{display:flex;align-items:center;gap:28px;font-size:13.5px}
.site-header nav a{text-decoration:none}
.menu-toggle{display:none;border:1px solid var(--line);padding:7px 12px;font-size:13px}
@media(max-width:820px){
  .menu-toggle{display:inline-block}
  .site-header{flex-wrap:wrap}
  .site-header nav{display:none;flex-basis:100%;flex-direction:column;align-items:flex-start;gap:14px;padding-top:16px}
  .site-header nav.open{display:flex}
}

/* CTAs */
.cta-row{margin:18px 0}
.button{display:inline-flex;align-items:center;justify-content:space-between;gap:20px;max-width:100%;padding:14px 20px;text-decoration:none;font-size:13.5px;font-weight:600;line-height:1.4;text-align:left;border:1px solid var(--ink);background:var(--ink);color:var(--paper);border-radius:var(--r)}
.button-quiet{background:transparent;color:var(--ink)}
.text-button{border-bottom:1px solid currentColor;padding:6px 0;font-size:14px;text-align:left}

/* Hero skeleton */
.hero-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,1fr);gap:clamp(32px,6vw,96px);align-items:start}
.hero-copy .eyebrow{font-size:12px;letter-spacing:.09em;text-transform:uppercase;margin-bottom:22px}
.hero-copy .eyebrow strong{font-weight:500}
.hero-intro>p:first-child{font-size:1.25em;line-height:1.5}
.hero-actions{margin-top:26px}
.hero-actions .cta-row{margin:0 0 10px}
.hero-actions .note{margin-bottom:22px}
.hero-actions .offer{font-size:14px;margin-bottom:8px}
@media(max-width:900px){.hero-grid{grid-template-columns:1fr}}

/* Video placeholder */
.video-placeholder{margin:34px 0;min-height:340px;display:flex;flex-direction:column;justify-content:space-between;padding:32px 36px;border:1px solid var(--line)}
.video-diagram{display:flex;justify-content:center;align-items:center;gap:40px;padding:36px 0;font-family:var(--display);font-size:clamp(56px,9vw,100px);line-height:1}
.video-equal{font-size:.4em;opacity:.55}
.video-caption{display:flex;justify-content:space-between;gap:16px;padding-top:16px;border-top:1px solid var(--line);font-size:12.5px}

/* Two explanations */
.explanations{margin:30px 0;padding:30px;border:1px solid var(--line);background:var(--surface)}
.lesson-tabs{display:flex;gap:18px;border-bottom:1px solid var(--line)}
.lesson-tabs button{flex:1;padding:12px 0;margin-bottom:-1px;border-bottom:2px solid transparent;text-align:left;font-size:14px}
.lesson-tabs button[aria-selected=true]{border-bottom-color:var(--accent);font-weight:600}
.lesson-panel{display:grid;grid-template-columns:1fr 1fr;gap:44px;padding:30px 0}
.lesson-copy h3{font-size:clamp(24px,2.6vw,32px);margin-bottom:16px}
.lesson-copy p{font-size:14.5px}
.fraction-model>div:not(.fraction-sum){display:grid;grid-template-columns:36px 1fr;gap:12px;margin-bottom:18px;align-items:center}
.fraction-model>div>span{font-size:24px;font-family:var(--display)}
.fraction-model b{grid-column:2;font-size:12px;font-weight:400;opacity:0;transition:opacity .4s}
.fraction-strip{height:54px;display:grid;grid-template-columns:repeat(6,1fr);border:1px solid var(--ink);overflow:hidden}
.fraction-strip i{border-right:0 solid var(--ink);transition:border .35s}
.fraction-strip i:last-child{border:0}
.fraction-strip.half i:nth-child(-n+3){background:var(--fill-a,#999)}
.fraction-strip.half i:nth-child(3){border-right:1px solid var(--ink)}
.fraction-strip.third i:nth-child(-n+2){background:var(--fill-b,#ccc)}
.fraction-strip.third i:nth-child(2),.fraction-strip.third i:nth-child(4){border-right:1px solid var(--ink)}
.is-divided .fraction-strip i:not(:last-child){border-right:1px solid var(--ink)}
.is-divided .fraction-model b{opacity:1}
.fraction-sum{display:flex;justify-content:space-between;font-family:var(--display);font-size:32px;padding-top:18px;border-top:1px solid var(--line)}
.worked-steps{list-style:none;padding:0;margin:0}
.worked-steps li{display:flex;justify-content:space-between;align-items:center;gap:20px;padding-bottom:14px;margin-bottom:14px;border-bottom:1px solid var(--line)}
.worked-steps span{font-size:12.5px}
.worked-steps strong{font-family:var(--display);font-size:26px;font-weight:400}
.fresh-question{display:flex;flex-wrap:wrap;justify-content:space-between;gap:18px;padding-top:24px;border-top:1px solid var(--line)}
.fresh-question p{margin:4px 0 0;font-size:19px}
.fresh-options{display:flex;gap:10px}
.fresh-options button{width:68px;min-height:54px;border:1px solid var(--line);font-family:var(--display);font-size:26px}
.fresh-options button:hover,.fresh-options button.chosen{background:var(--ink);color:var(--paper)}
.fresh-feedback{flex-basis:100%;font-size:14px;color:var(--accent);margin:0}
@media(max-width:720px){.lesson-panel{grid-template-columns:1fr;gap:26px}.explanations{padding:20px}}

/* Reviews */
blockquote{margin:0;padding:22px 26px 18px 0}
.review-grid{display:grid;grid-template-columns:1fr 1fr;border-top:1px solid var(--line)}
.review-grid blockquote+blockquote{border-left:1px solid var(--line);padding-left:26px}
blockquote p{font-family:var(--display);font-size:clamp(21px,2.3vw,28px);line-height:1.3}
blockquote footer{font-size:11.5px;letter-spacing:.04em;color:var(--muted)}
@media(max-width:720px){.review-grid{grid-template-columns:1fr}.review-grid blockquote+blockquote{border-left:0;border-top:1px solid var(--line);padding-left:0}}

/* Exchange, cards, reports, records */
.exchange{border:1px solid var(--line);padding:24px;background:var(--surface)}
.exchange-row{display:grid;grid-template-columns:86px 1fr;gap:10px;padding:16px 0;border-top:1px solid var(--line)}
.exchange-row span{font-size:11px;text-transform:uppercase;letter-spacing:.05em}
.exchange-row p{font-size:15px;margin:0}
.exchange-row b{grid-column:2;font-size:11px;color:var(--accent);font-weight:500}
.goal-card{padding:28px;border:1px solid var(--line);background:var(--surface);margin:28px 0}
.goal-card h3{margin-bottom:22px}
.goal-card dl>div,.weekly-report dl>div,.course-record dl>div{display:grid;grid-template-columns:118px 1fr;gap:18px;padding:12px 0;border-top:1px solid var(--line);font-size:13.5px}
.goal-card dt,.weekly-report dt,.course-record dt{color:var(--muted)}
.report-samples{margin:32px 0;display:grid;grid-template-columns:minmax(0,1.35fr) minmax(0,1fr);gap:26px;align-items:start}
.weekly-report,.email-sample{padding:28px;border:1px solid var(--line);background:var(--surface)}
.report-top{display:flex;justify-content:space-between;gap:20px;margin-bottom:26px}
.report-top h3{font-size:clamp(24px,2.6vw,32px)}
.report-top>span{font-size:11.5px;color:var(--muted);text-align:right}
.report-controls{display:flex;gap:14px;margin:18px 0;font-size:12.5px}
.report-controls label{flex:1}
.report-controls select{display:block;width:100%;margin-top:5px;padding:9px;border:1px solid var(--line);background:transparent;border-radius:0}
.report-note{padding-top:14px;border-top:1px solid var(--line);font-weight:600;font-size:14px}
.email-from{font-size:11.5px;color:var(--muted)}
.email-sample h3{margin:16px 0;font-size:clamp(22px,2.3vw,27px)}
.email-sample p{font-size:13.5px}
.team-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:26px;margin:26px 0 40px}
.portrait{height:240px;overflow:hidden;border:1px solid var(--line);padding-top:18px;display:flex;justify-content:center}
.portrait svg{height:100%;fill:currentColor;opacity:.14}
.team-person h3{margin:16px 0 4px;font-size:22px}
.team-person p{font-size:12.5px;margin:0 0 4px}
.record-grid{display:grid;grid-template-columns:1fr 1fr;gap:28px;margin:34px 0}
.course-record,.outside-report{padding:30px;border:1px solid var(--line);background:var(--surface)}
.record-grid h3{font-size:clamp(26px,3vw,36px);margin-bottom:24px}
.outside-report p{font-size:14px}
.score-example{display:grid;grid-template-columns:1fr 1fr;grid-template-rows:auto auto;grid-auto-flow:column;padding:18px 0;margin:18px 0;border-block:1px solid var(--line)}
.score-example span{font-size:11.5px}
.score-example strong{font-size:44px;font-family:var(--display);font-weight:400}
.course-path{padding:26px 0;margin:26px 0;border-block:1px solid var(--line);font-family:var(--display);font-size:clamp(19px,2.2vw,24px);line-height:1.9}
.course-path span{margin:0 8px;opacity:.5}
.three-up{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin:26px 0}
.three-up h3{font-size:21px;margin-bottom:12px}
.three-up p{font-size:14.5px}
.closing-grid{display:grid;grid-template-columns:1fr 1fr;gap:34px;margin:34px 0}
.closing-grid ul{list-style:none;padding:0}
.closing-grid li{padding:14px 0;border-top:1px solid var(--line);font-size:14.5px}
.risk-panel p{padding:14px 0;margin:0;border-top:1px solid var(--line);font-size:14.5px}
.ledger{display:grid;grid-template-columns:repeat(4,1fr);gap:26px;margin:34px 0 10px}
.ledger-group h3{font-size:19px;margin-bottom:14px;padding-bottom:10px;border-bottom:1px solid var(--line)}
.ledger-item{display:grid;grid-template-columns:auto 1fr;gap:12px;padding:12px 0}
.ledger-item h4{font-family:var(--body);font-size:14.5px;font-weight:600;margin-bottom:4px}
.ledger-item p{font-size:13.5px;margin:0}
.ledger-item .n{font-family:var(--mono);font-size:12px;padding-top:3px}
.carry{display:flex;align-items:center;gap:18px;flex-wrap:wrap}
.carry>div{flex:1;min-width:120px}
.carry span{display:block;font-size:11px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.carry strong{display:block;font-family:var(--display);font-weight:400;font-size:clamp(24px,2.6vw,30px);margin-top:8px}
.lesson-grid,.pay-grid,.deal-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:40px;align-items:start}
@media(max-width:960px){.ledger{grid-template-columns:1fr 1fr}}
@media(max-width:820px){.report-samples,.record-grid,.closing-grid,.lesson-grid,.pay-grid,.deal-grid,.three-up{grid-template-columns:1fr}.team-grid{grid-template-columns:1fr 1fr}}
@media(max-width:560px){.ledger,.team-grid{grid-template-columns:1fr}}

/* Tables */
.table-scroll{overflow-x:auto;margin:26px 0;-webkit-overflow-scrolling:touch}
table{font-size:13px;line-height:1.55}
th,td{padding:16px 14px;border:1px solid var(--line);min-width:150px}
th:first-child,td:first-child{min-width:130px}
th{font-weight:600}
.table-notes{font-size:13px;color:var(--muted)}
.table-notes em{font-style:normal}

/* Price selector */
.price-selector{margin:28px 0;padding:22px 0;border-block:1px solid var(--line)}
.price-selector>label{font-size:13px;margin-right:16px}
.price-selector>select{padding:8px 26px 8px 12px;border:1px solid var(--ink);background:transparent;font-size:13px;border-radius:0}
.price-comparison{display:grid;grid-template-columns:1fr 44px 1fr;align-items:center;margin:22px 0}
.price-comparison div>span{display:block;font-size:11px;letter-spacing:.07em;text-transform:uppercase}
.price-comparison s{font-family:var(--display);font-size:clamp(40px,6vw,64px);color:var(--muted);text-decoration-thickness:1px;font-weight:400}
.price-comparison strong{font-family:var(--display);font-size:clamp(56px,9vw,96px);line-height:1.1;font-weight:500}
.price-selector>p{font-size:13px}
@media(max-width:560px){.price-comparison{grid-template-columns:1fr;gap:6px}.price-comparison>span{display:none}}

/* Footer */
.site-footer{display:grid;grid-template-columns:1.3fr 2fr;gap:36px;padding:56px var(--pad) 22px;border-top:1px solid var(--line)}
.site-footer nav{display:grid;grid-template-columns:1fr 1fr;gap:10px 30px;font-size:13px}
.site-footer nav a{text-decoration:none;overflow-wrap:anywhere}
.site-footer p{font-size:13px;margin-top:12px}
.footer-bottom{grid-column:1/-1;border-top:1px solid var(--line);padding-top:20px;color:var(--muted);font-size:12.5px}
@media(max-width:720px){.site-footer{grid-template-columns:1fr}}

/* Motion */
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.001ms!important;animation-delay:0s!important;transition-duration:.001ms!important}}

/* Real profile photos; initials remain for team members without a photo. */
.portrait.portrait-photo{padding-top:0}
.portrait-photo img{display:block;width:100%;height:100%;object-fit:cover;object-position:center top}
.portrait-1.portrait-photo img{object-position:center 35%}
.review footer{display:flex;align-items:center;gap:12px}
.review-photo{display:block;flex-shrink:0;width:56px;height:56px;border-radius:50%;object-fit:cover;object-position:center 30%}