/* Shared visual language: one accent, calm surfaces, clear controls. */
:root{--paper:#f3f3ef;--card:#fff;--ink:#222b2a;--muted:#5d6864;--line:#daddd7;--teal:#2a535d;--accent:#2a535d;--radius:18px;--shadow:0 3px 16px #182b4510}
body{font-family:-apple-system,BlinkMacSystemFont,"Inter","Segoe UI",sans-serif;color:var(--ink);background:var(--paper);font-size:16px;-webkit-font-smoothing:antialiased}
h1,h2,h3{color:var(--ink);font-weight:650;letter-spacing:-.035em}p{color:var(--muted)}
button{touch-action:manipulation}button,a,input,textarea,select{scroll-margin:20px}
button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #2771dc;outline-offset:3px}
.button,.button.lime,.button.start-button,.answer-action .button.full{background:#2a535d;color:#fff;border:1px solid #2a535d;box-shadow:none;border-radius:12px;min-height:48px;font-weight:600}
.button:hover:not(:disabled),.button.start-button:hover:not(:disabled),.answer-action .button.full:hover{background:#173e47;border-color:#173e47}
.button.secondary{background:#fff;color:#234c86;border-color:#d6dfeb}.button.secondary:hover:not(:disabled){background:#edf3fc;border-color:#b7c9e3}
.button.danger{background:#a33035;border-color:#a33035}.link-btn{color:#2a535d;font-weight:600}
.small-label,.eyebrow{color:#576980;font-size:10px;letter-spacing:1.5px;font-weight:650}
.studio-header{max-width:1260px;min-height:80px;border:0;padding:18px 32px;gap:26px}
.studio-header .brand img{width:34px;height:34px;border-radius:10px}.studio-header .brand b{font-size:32px}.brand-stop{color:#2a535d}
.studio-nav{background:#e9edf3;border:1px solid #e3e8f0;padding:4px;border-radius:13px;gap:2px}
.studio-nav .nav-item{border-radius:9px;min-height:39px;padding:8px 12px;color:#53647a;font-size:12px}
.studio-nav .nav-item.active{background:#fff;color:#234e91;box-shadow:0 1px 4px #20344913}
.studio-nav .nav-item:hover{background:#f8faff}.studio-account .icon-btn{min-width:44px;min-height:44px;color:#52657b}
.profile-btn{background:#fff;border-color:#dce3ec;min-height:44px;border-radius:12px;color:#253c5b}.learner-mark{border-radius:8px}
.studio-main{max-width:1140px;padding-top:30px}.studio-intro{margin-bottom:27px}.studio-intro h1{font-size:43px;font-weight:670;letter-spacing:-1.5px;line-height:1.12;margin:9px 0 12px}.studio-intro p{font-size:16px;color:#647084}
.studio-footer{border-color:#daddd7;color:#5a6a7f}.studio-footer small,.studio-footer .link-btn{color:#5a6a7f}.studio-footer .link-btn{min-height:44px}
.start-layout{gap:20px;grid-template-columns:1.13fr 1fr}.practice-start{background:linear-gradient(135deg,#203a63,#1c2c48);border:0;border-radius:22px;padding:30px 32px;min-height:318px;box-shadow:0 9px 25px #20344f12}
.practice-topline .small-label{color:#cfdbed}.practice-count{border-color:#ffffff38;background:#ffffff0a;border-radius:6px;color:#e2eafa;font-size:11px}
.practice-copy h2{font-size:35px;font-weight:620;line-height:1.15;color:#fff;letter-spacing:-1.1px}.practice-copy p{color:#d7e0ed;font-size:14px;line-height:1.65;max-width:350px}
.practice-start .start-button{background:#fff;border-color:#fff;color:#244c83;min-height:48px}.practice-start .start-button:hover{background:#e3edff;border-color:#e3edff}
.practice-start-actions>span{color:#d4e1f3;font-size:12px}.practice-rule{display:none}
.home-model{background:#fff;border:1px solid #e0e5ed;border-radius:22px;padding:28px;box-shadow:var(--shadow)}.home-model h3{color:#243852;font-size:25px;line-height:1.2}.sample-topic,.same-amount small,.home-model p.model-instruction{color:#556b84}
.fraction-touch{border-color:#9ab4d7;border-radius:8px;height:57px}.fraction-touch button{background:#f2f5fa}.fraction-touch button[aria-pressed=true]{background:#376ba9}.same-amount b{font-weight:620;color:#2d568a}.same-amount i{color:#6b7b8e}
.practice-routes{grid-template-columns:repeat(4,minmax(0,1fr));gap:13px}.section-top{margin:29px 0 15px}.section-top h2{font-size:21px;font-weight:630}
.route-card{padding:21px;border:1px solid #e0e5ed;border-radius:17px;background:#fff;min-height:178px;box-shadow:0 2px 10px #182b4505}.route-card:hover{background:#fff;border-color:#a5bfdf;box-shadow:0 5px 18px #182b4510;transform:translateY(-2px)}
.route-symbol{width:39px;height:39px;border-radius:11px;background:#eaf1fc!important;color:#3567a7!important}.route-symbol .icon{width:22px;height:22px}.route-copy h3{font-size:18px;color:#243852;font-weight:650}.route-copy small{color:#5f6d80;font-size:13px;line-height:1.55}.route-arrow{color:#567397}.home-record{border-color:#daddd7;color:#5b6d81}
.page-intro{max-width:720px}.page-intro h1{font-size:39px;line-height:1.15}.page-intro p{font-size:15px;line-height:1.65}
.search{background:#fff;border-color:#d9e1ec;border-radius:12px;min-height:52px}.search input{font-size:15px}
.topic-card,.skill-row,.paper-card,.reasoning-card,.lab-menu-card,.teacher-card,.topic-record,.saved-work-item,.saved-work-shortcut,.practice-week{background:#fff;border-color:#e0e5ed;border-radius:16px;box-shadow:0 2px 10px #182b4505}
.topic-card:hover,.skill-row:hover,.saved-work-item:hover{background:#f5f9ff;border-color:#b9cce6}.tile-icon{border-radius:11px}.topic-card h3,.skill-row h3{font-weight:620;color:#243852}.topic-card p,.skill-row p{color:#62718a}.skill-list{gap:10px}
.paper-card .paper-num{background:#edf3fc;color:#3567a7;border:0;border-radius:13px}.paper-card h3{color:#233c5a}.paper-card p{color:#5f7084}.reasoning-card-model,.lab-menu-visual{border-radius:12px}.reasoning-card h3{color:#243852}.reasoning-card-top{color:#54677e}
.info-box,.model-strip,.result-hero{background:#edf2f9;border:1px solid #dce5f0;border-radius:16px;color:#4b637d}.model-strip-icon{background:#e0eafa;color:#345c94;border-radius:10px}.info-box p{color:#4d647e}
.practice-tabs{display:flex;gap:4px;width:max-content;max-width:100%;padding:4px;background:#e7ecf3;border-radius:12px;margin:0 0 24px}.practice-tabs button{padding:8px 19px;min-height:44px;border-radius:9px;background:transparent;color:#4b627e;font-size:14px;font-weight:600}.practice-tabs button[aria-current]{background:#fff;color:#204e93;box-shadow:0 1px 4px #23365415}
.foundation-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.foundation-card{text-align:left;padding:25px;background:#fff;border:1px solid #dfe6ef;border-radius:18px;display:flex;flex-direction:column;min-width:0;transition:border-color .15s,box-shadow .15s}.foundation-card:hover{border-color:#a5c0e5;box-shadow:var(--shadow)}
.foundation-symbol{display:grid;place-items:center;width:43px;height:43px;border-radius:13px;background:#edf3fc;color:#3567a7;margin-bottom:20px}.foundation-symbol .icon{width:24px;height:24px}.foundation-card h2{font-size:21px;line-height:1.25;margin:0 0 9px}.foundation-card p{font-size:14px;line-height:1.55;margin:0 0 24px}.foundation-card-bottom{margin-top:auto;display:flex;justify-content:space-between;gap:12px;font-size:12px;font-weight:550;color:#456491}.foundation-card-bottom .icon{width:17px;height:17px}
.foundation-path{list-style:none;margin:28px 0;padding:0;max-width:820px}.foundation-path>li{display:flex;gap:23px;padding:0 0 28px;position:relative}.foundation-path>li:not(:last-child)::before{content:"";position:absolute;left:20px;top:45px;bottom:0;width:1px;background:#c9d7e9}.foundation-number{display:grid;place-items:center;width:41px;height:41px;flex-shrink:0;background:#e5eefb;border:1px solid #c7d9f2;border-radius:50%;color:#315d98;font-size:16px;font-weight:650}.foundation-path>li>div{flex:1;background:#fff;border:1px solid #e0e6ef;border-radius:17px;padding:24px;min-width:0}.foundation-path h2{font-size:24px;margin:8px 0 12px}.foundation-path p{font-size:15px;line-height:1.65;margin:0 0 19px;max-width:590px}.foundation-note{font-size:14px;color:#617189}
.foundation-help{display:grid;gap:9px}.foundation-help>button{display:flex;align-items:center;gap:13px;text-align:left;padding:15px;background:#fff;border:1px solid #dce4ee;border-radius:13px}.foundation-help>button>span:first-child{width:31px;height:31px;flex-shrink:0;display:grid;place-items:center;border-radius:50%;background:#edf3fc;color:#315d98;font-weight:650;font-size:14px}.foundation-help>button>span:nth-child(2){flex:1;min-width:0}.foundation-help b{display:block;font-size:16px;color:#263e5d}.foundation-help small{display:block;margin-top:4px;font-size:13px;line-height:1.55;color:#60728a}.foundation-help .icon{width:18px;height:18px;flex-shrink:0}.foundation-help [aria-current]{border-color:#628bc4;background:#f2f7ff}
/* Practice always has one question, one answer area and one model switch. */
body.learning{background:#f3f3ef}.player{max-width:1240px;padding-left:24px;padding-right:24px;grid-template-rows:48px 1px minmax(0,1fr)48px;gap:10px}
.player>main{grid-template-rows:44px minmax(0,1fr);gap:10px}.player>main:has(.foundation-ribbon){grid-template-rows:auto 44px minmax(0,1fr)}
.player-heading{font-size:13px;gap:12px}.player-heading>span:first-child{flex:1;color:#596c84}.player-heading .question-count{font-size:13px;flex-shrink:0}.question-count span{font-size:11px;color:#617288}.practice-divider{height:1px;background:#dce3ec;width:100%}
.model-toggle{display:inline-flex;align-items:center;gap:7px;flex-shrink:0;min-height:42px;padding:7px 12px;font-size:12px;font-weight:600;line-height:1.3;border:1px solid #cfdbeb;border-radius:10px;background:#fff;color:#2d568b}.model-toggle:hover{background:#eaf2ff}.model-toggle[aria-expanded=false]{background:#e9f1ff;border-color:#b8cceb}.model-toggle .icon{width:17px;height:17px}
.question-layout{grid-template-columns:minmax(0,1.65fr) minmax(290px,1fr);gap:0;border:1px solid #dce4ed;border-radius:22px;background:#fff;box-shadow:0 4px 20px #192e4e08}.question-card{padding:29px;background:#fff;min-height:0;border-radius:0;border:0;box-shadow:none}
.question-card h1{font-weight:610;color:#263a3d;line-height:1.35;font-size:clamp(24px,2.3vw,31px);letter-spacing:-.55px}.question-copy{flex-shrink:0}.question-expression{background:#f0f5fc;color:#254e85;border:1px solid #e0e9f6;border-radius:13px;font-size:clamp(34px,4vw,52px);font-weight:580}
.question-visual{background:#f7f9fd;background-image:none;border:1px solid #e1e8f2;border-radius:14px;padding:5px 13px 13px;margin-top:20px;min-height:170px;flex:1;overflow:visible}.question-visual[hidden]{display:none!important}.visual-label{font-size:10px;letter-spacing:.1px;text-transform:none;color:#5f748f;min-height:40px;flex-shrink:0}.visual-label .link-btn{min-height:40px;background:transparent;font-size:12px;color:#315e9b;gap:6px}
.question-visual .model{overflow:hidden;min-height:95px}.question-visual .model-table{background:#fff;font-size:15px}.model-table th{color:#355575}.model-table td,.model-table th{border-color:#d4e0ee}.question-visual .model-table-wrap{border-radius:8px}
.answer-panel{background:#f8fafd;border:0;border-left:1px solid #e0e6ef;border-radius:0;box-shadow:none;padding:25px}.answer-panel h2{color:#334c6c;font-size:16px}.answer-input,.text-input,select{border:1.5px solid #9fb6d3;border-radius:11px;background:#fff;color:#254367}.answer-input{font-size:27px;height:55px}.answer-input::placeholder{color:#6c7d96;font-size:16px}.pad-toggle{background:#eaf0f8;border:1px solid #d7e2ef;border-radius:10px;color:#456c9a;min-height:44px;min-width:40px}.choice{border-color:#c8d6e8;border-radius:11px;background:#fff;color:#294568}.choice.selected{border-color:#457abe;background:#eaf2ff}.choice .choice-dot{border-color:#8ca8cd}
.answer-action .button.full{min-height:49px}.answer-action .button.success-action{background:#2a535d;border-color:#2a535d}.answer-confirmed{background:#e6f2ed;color:#255a45;border-radius:11px}.feedback{border-radius:11px;background:#edf7f1;border-color:#d3e9de}.feedback strong{color:#285943}.feedback p{color:#416554}.feedback.retry{background:#fff6e6;border-color:#e9d9b4}.feedback.retry strong,.feedback.retry p{color:#705b2f}.your-first-answer{background:#ebf1fa;color:#3d5c80;border-radius:9px}.input-help{font-size:11px;color:#536c8c}
.player-tools{gap:18px}.player-tools button{color:#47678f;font-size:13px;border-radius:10px;min-height:44px;flex:0 1 180px}.player-tools button:hover{background:#e7eef8}.screen-control{background:#fff;border-color:#d2deeb;border-radius:10px;min-height:44px;font-size:12px;color:#40658c}.exit-practice{min-height:44px;font-size:13px;color:#42638c}.player-top .icon-btn{min-width:44px;min-height:44px;color:#456685}
.foundation-ribbon{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:1px 9px;background:#eaf1fb;border:1px solid #d9e4f3;border-radius:10px}.foundation-ribbon button{display:flex;align-items:center;gap:8px;min-height:42px;background:transparent;color:#365d92;font-size:12px;font-weight:600;text-align:left}.foundation-ribbon button>span{color:#647b98;font-weight:400;margin-left:5px}.foundation-ribbon .icon{width:17px;height:17px;flex-shrink:0}
.foundation-next{padding-top:12px;margin-top:12px;border-top:1px solid #d7e5de}.foundation-next button{min-height:44px;text-align:left;color:#2a535d;background:transparent;font-size:13px;font-weight:600}
/* Help is one calm sheet; the depth appears only when requested. */
dialog{background:#fff;border:1px solid #d3deec;border-radius:22px;box-shadow:0 24px 90px #192c4940;padding:28px}dialog::backdrop{background:#13253b66;backdrop-filter:blur(6px)}dialog.learning-dialog{background:#fff}.dialog-heading{border-color:#e1e7f0}.dialog-heading h2{font-size:24px;color:#233e62}.dialog-heading .icon-btn{min-width:44px;min-height:44px;border-radius:12px;background:#f0f4fa;color:#476d9e}.dialog-body>p{color:#5b6e88;font-size:15px;line-height:1.65}
.help-menu{gap:0;border:1px solid #dce4ef;border-radius:15px;overflow:hidden}.help-menu>button{background:#fff;border:0;border-bottom:1px solid #e3e9f1;border-radius:0;padding:18px 16px;gap:14px;min-height:75px}.help-menu>button:last-child{border-bottom:0}.help-menu>button:hover{background:#f3f7fd}.help-menu b{font-size:16px;color:#2b496e}.help-menu small{font-size:13px;color:#5d728e;line-height:1.5}.help-menu>button>.icon:first-child{color:#416ea7}.support-question,.hint-box{background:#f0f5fc;border-color:#dce6f3;border-radius:13px}.step-instruction{color:#253e5f}.step-result{border-radius:11px;background:#e9f3ec}.step-expression{color:#2b558b}.keypad button{border-radius:11px;background:#f3f6fb;border-color:#d5dfed}.viewer-viewport{background:#f7f9fc;border-color:#dce5ef;border-radius:14px}.viewer-head h2{color:#264565}.viewer-controls button{border-radius:10px;min-height:44px;min-width:44px;background:#edf3fb;border-color:#d6e2ef;color:#315f98}.viewer-description{background:#f2f6fc;border-radius:11px}.viewer-description summary{min-height:44px;display:flex;align-items:center;color:#365c8d}.viewer-tip{color:#63758f}.toggle[aria-checked=true]{background:#326abb}
@media(max-width:1000px){.studio-header{gap:14px;padding-left:23px;padding-right:23px}.studio-nav .nav-item{padding:8px 10px}.profile-btn>span:last-child{display:none}.foundation-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.practice-routes{grid-template-columns:repeat(2,minmax(0,1fr))}.route-card{min-height:147px}.question-layout{grid-template-columns:minmax(0,1.35fr) minmax(260px,1fr)}}
@media(max-width:650px){
 .studio-header{min-height:72px;padding:13px 19px;gap:10px}.studio-header .brand b{font-size:30px}.studio-header .brand small{font-size:9px}.studio-header .brand img{width:32px;height:32px}.studio-account{gap:0}.studio-account .icon-btn{width:44px}.profile-btn{padding:5px;min-width:41px}.studio-main{padding:22px 19px 18px}
 .studio-nav{position:fixed;bottom:0;left:0;right:0;z-index:50;max-width:none;width:100%;border:0;border-top:1px solid #dce4ee;border-radius:0;background:#fffffff2;backdrop-filter:blur(18px);padding:7px 9px max(7px,env(safe-area-inset-bottom));display:grid;grid-template-columns:repeat(5,1fr);gap:5px;box-shadow:0 -4px 24px #263e5d06}.studio-nav .nav-item{padding:5px 3px;min-height:51px;gap:5px;font-size:10px;border-radius:12px;flex-direction:column}.studio-nav .nav-item .icon{width:21px;height:21px}.studio-nav .nav-item.active{background:#eaf1fc;box-shadow:none}.studio-shell{padding-bottom:76px}
 .studio-intro h1{font-size:33px;letter-spacing:-1.2px;margin:8px 0 12px}.studio-intro p{font-size:14px;line-height:1.6}.studio-intro{margin-bottom:22px}.practice-start{border-radius:19px;padding:23px;min-height:0}.practice-copy{margin-top:19px}.practice-copy h2{font-size:29px;line-height:1.17;letter-spacing:-.75px}.practice-copy p{font-size:14px;line-height:1.6;margin-top:12px;max-width:none}.practice-start-actions{margin-top:21px;gap:12px}.practice-start-actions>span{font-size:11px}.practice-count{font-size:10px}.practice-start .start-button{font-size:14px;min-height:47px}.home-model{border-radius:19px;padding:24px}.home-model h3{font-size:23px}.fraction-touch{height:54px}.same-amount b{font-size:27px}.sample-topic{font-size:12px}.same-amount small{font-size:11px}
 .practice-routes{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.route-card{display:flex;flex-direction:column;align-items:flex-start;padding:18px 15px;min-height:175px;border-radius:16px;position:relative;gap:0}.route-symbol{width:34px;height:34px;border-radius:10px;margin-bottom:13px}.route-symbol .icon{width:20px;height:20px}.route-copy h3{font-size:17px;margin:0 0 7px}.route-copy small{font-size:12px;line-height:1.5}.route-arrow{position:absolute;top:25px;right:15px}.route-arrow .icon{width:17px;height:17px}.section-top{margin:25px 0 14px}.section-top h2{font-size:20px}.home-record{font-size:12px;gap:10px;line-height:1.65}.studio-footer{font-size:11px}.studio-footer .link-btn{font-size:11px}
 .page-intro h1{font-size:32px;letter-spacing:-1px}.page-intro p{font-size:14px;line-height:1.65}.practice-tabs{width:100%;margin-bottom:20px}.practice-tabs button{flex:1;padding:8px 10px;font-size:13px;min-height:44px}.search input{font-size:16px}.topic-card{padding:18px 16px;border-radius:14px}.topic-card h3{font-size:17px}.topic-card p{font-size:12px}.skill-row{border-radius:13px;padding:17px 14px}.skill-row h3{font-size:16px;line-height:1.4}.skill-row p{font-size:12px}.model-strip p{font-size:13px}.model-strip .button{font-size:12px;min-height:44px}
 .foundation-grid{grid-template-columns:1fr;gap:11px}.foundation-card{display:grid;grid-template-columns:38px 1fr;column-gap:15px;padding:19px;border-radius:16px}.foundation-symbol{width:38px;height:38px;border-radius:11px;grid-row:1/4;margin:0}.foundation-symbol .icon{width:22px;height:22px}.foundation-card h2{font-size:19px;margin:0 0 7px}.foundation-card p{font-size:13px;line-height:1.6;margin:0 0 13px}.foundation-card-bottom{grid-column:2;font-size:12px}.foundation-path>li{gap:13px;padding-bottom:19px}.foundation-number{width:33px;height:33px;font-size:14px}.foundation-path>li:not(:last-child)::before{left:16px;top:37px}.foundation-path>li>div{padding:20px 17px;border-radius:16px}.foundation-path h2{font-size:22px;margin:6px 0 12px}.foundation-path p{font-size:14px;line-height:1.6}.foundation-path .button{font-size:13px;min-height:46px;padding:10px 12px}.foundation-note{font-size:13px;line-height:1.6}
 .player{padding:7px 12px max(7px,env(safe-area-inset-bottom));grid-template-rows:46px 1px minmax(0,1fr)44px;gap:7px}.player>main{grid-template-rows:44px minmax(0,1fr);gap:7px}.player>main:has(.foundation-ribbon){grid-template-rows:auto 44px minmax(0,1fr)}.player-heading{gap:8px;font-size:12px}.player-heading>span:first-child .icon{display:none}.player-heading b{font-size:12px}.player-heading .question-count{font-size:12px}.question-count span{display:none}.model-toggle{min-height:42px;padding:7px 10px;font-size:12px;border-radius:10px;gap:6px}.model-toggle .icon{width:16px;height:16px}
 .question-layout{display:flex;flex-direction:column;border-radius:18px;gap:0}.question-card{flex:1;min-height:75px;padding:18px;background:#fff;border:0;border-radius:0;box-shadow:none}.question-card h1{font-size:23px;line-height:1.35;letter-spacing:-.4px}.word-question h1{font-size:20px;line-height:1.4}.question-expression{font-size:34px;margin:13px 0 0;padding:10px 13px;border-radius:11px}.question-visual{flex:1 0 155px;min-height:145px;max-height:340px;margin-top:14px;padding:2px 9px 10px;border-radius:12px;overflow:hidden}.word-question .question-visual{flex-basis:135px;min-height:125px}.question-visual .model{min-height:70px}.visual-label{min-height:36px;font-size:10px}.visual-label .link-btn{min-height:36px;font-size:11px}.question-visual .model-table{font-size:13px}.question-visual .model-table td,.question-visual .model-table th{padding:8px}
 .answer-panel{padding:13px 14px;border:0;border-top:1px solid #dde6f0;border-radius:0;box-shadow:none;background:#f8fafd;max-height:53%}.answer-panel h2{font-size:14px;line-height:1.4;margin:0 0 9px}.answer-input{font-size:25px;height:51px;border-radius:10px}.answer-input::placeholder{font-size:16px}.pad-toggle{width:37px;min-width:37px;height:44px;min-height:44px;border-radius:10px}.number-answer:not(.answer-done){grid-template-columns:minmax(0,1fr) 123px;gap:10px}.answer-action .button.full{min-height:49px;border-radius:11px;font-size:13px;padding:10px 12px}.number-answer:not(.answer-done) .answer-action .button{font-size:13px}.answer-panel .choice{font-size:15px;min-height:45px;border-radius:10px;padding:10px}.input-help{font-size:11px}.answer-panel .workings{font-size:16px}.answer-done .answer-action .button{font-size:13px}.answer-done .answer-action .link-btn{font-size:12px;min-height:44px}.feedback strong{font-size:14px}.feedback p{font-size:12px;line-height:1.5}.answer-confirmed{border-radius:9px}.answer-confirmed strong{font-size:24px}
 .player-tools{gap:4px;justify-content:space-between}.player-tools button{flex:1;padding:7px 4px;font-size:12px;gap:6px;min-height:44px}.player-tools .icon{width:18px;height:18px}.exit-practice{font-size:12px;gap:8px}.screen-control{font-size:12px;padding:7px 10px}.player-top .actions{gap:3px}.foundation-ribbon{padding:0 8px;gap:8px}.foundation-ribbon button{font-size:11px;min-height:38px;gap:5px}.foundation-ribbon button>span{display:none}.foundation-ribbon .icon{width:15px;height:15px}
 dialog{border-radius:20px;padding:22px}.dialog-heading h2{font-size:23px}.dialog-body>p{font-size:14px}.help-menu>button{padding:16px 13px;min-height:74px}.help-menu b{font-size:15px}.help-menu small{font-size:12px}.help-menu>button>.icon{width:21px;height:21px}.foundation-help>button{padding:13px;gap:11px}.foundation-help b{font-size:15px}.foundation-help small{font-size:12px}.step-instruction{font-size:25px;line-height:1.35}.step-expression{font-size:27px}.step-answer .button{min-height:47px;border-radius:11px}.viewer-controls button{min-height:44px}.viewer-head h2{font-size:18px}
 .large-text .word-question h1{font-size:26px}.large-text .question-card h1{font-size:28px}.large-text .route-copy small,.large-text .foundation-card p{font-size:15px}.large-text .number-answer:not(.answer-done){display:flex}.large-text .model-toggle{font-size:14px}.large-text .player-tools button{font-size:14px}.large-text .answer-panel h2,.large-text .answer-panel .choice{font-size:18px}
}
@media(max-width:360px){.studio-main{padding-left:15px;padding-right:15px}.studio-intro h1{font-size:30px}.practice-start{padding:21px}.practice-copy h2{font-size:27px}.route-card{padding:16px 13px}.route-copy h3{font-size:16px}.player{padding-left:9px;padding-right:9px}.player-heading>span:first-child{max-width:128px}.question-card{padding:15px}.word-question h1{font-size:19px}.number-answer:not(.answer-done){grid-template-columns:minmax(0,1fr) 109px;gap:7px}.answer-panel{padding:12px 10px}.answer-action .button.full{padding:9px;font-size:12px}.player-tools button{font-size:11px}.foundation-ribbon button{font-size:10px}}
@media(max-height:600px){.player{gap:5px;grid-template-rows:43px 1px minmax(0,1fr)44px}.player>main{gap:5px;grid-template-rows:42px minmax(0,1fr)}.question-card{padding:13px}.question-card h1{font-size:21px}.word-question h1{font-size:19px}.question-visual{min-height:130px;margin-top:10px}.answer-panel{padding:10px 12px}.question-expression{font-size:29px;margin-top:10px}.foundation-ribbon button{min-height:35px}}
.number-answer .button[data-action="check"]{white-space:nowrap;padding-inline:7px}
dialog.model-viewer{background:#f3f3ef}
.keyboard-open .question-visual{display:none}.keyboard-open .foundation-ribbon{display:none}.keyboard-open .player>main:has(.foundation-ribbon){grid-template-rows:44px minmax(0,1fr)}
.high-contrast{--ink:#0f223b;--muted:#334c6c;--line:#7893b8}.high-contrast .question-layout,.high-contrast .topic-card,.high-contrast .foundation-card,.high-contrast .route-card,.high-contrast .question-visual,.high-contrast .choice{border-color:#5c779d}.high-contrast .question-visual{background:#fff}.high-contrast p,.high-contrast .route-copy small,.high-contrast .foundation-help small{color:#324e70}
.reduced-motion button{transition:none}.reduced-motion .route-card:hover{transform:none}
@media(prefers-reduced-motion:reduce){button{transition:none}.route-card:hover{transform:none}}
@media print{.practice-tabs,.foundation-ribbon,.model-toggle{display:none}.question-visual[hidden]{display:none!important}.player{display:block;height:auto}.player>main{display:block}.question-layout{overflow:visible}.question-card,.answer-panel{overflow:visible;max-height:none}.question-visual{min-height:200px}}

/* 3.4 · Clear order: question, response, help. Colour signals an action. */
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif;color:#222b2a}
h1,h2,h3{font-weight:600;letter-spacing:-.025em}
.button,.button.lime,.button.start-button,.answer-action .button.full{border-radius:7px;background:#294851;border-color:#294851;box-shadow:none;font-weight:600}
.button:hover:not(:disabled),.button.start-button:hover:not(:disabled),.answer-action .button.full:hover{background:#193b43;border-color:#193b43;transform:none}
.button.secondary{background:#fff;color:#294851;border-color:#c9d1ce}.button.secondary:hover:not(:disabled){background:#edf1ee;border-color:#a6b6af}
.link-btn{color:#325e68}.small-label,.eyebrow{font-size:11px;letter-spacing:1.1px;color:#57645f;font-weight:600}
.studio-header{border-bottom:1px solid #daddd7;padding:16px 28px;min-height:78px;max-width:1200px}
.studio-header .brand img{width:30px;height:30px;border-radius:6px}.studio-header .brand b{font-size:30px;font-weight:600}.brand small{letter-spacing:1.5px}
.studio-nav{padding:0;gap:4px;background:transparent;border:0;border-radius:0}
.studio-nav .nav-item{min-height:44px;border-radius:6px;font-size:13px;color:#5b6864;padding:10px 12px;gap:7px}
.studio-nav .nav-item .icon{width:17px;height:17px}.studio-nav .nav-item.active{background:#e3e9e4;box-shadow:none;color:#243e42}.studio-nav .nav-item:hover{background:#e9eee9}
.profile-btn{border-radius:7px;border-color:#ccd5ce;color:#3c4c49}.learner-mark{border-radius:4px;background:#e7ece8;color:#294851}
.studio-main{max-width:1120px;padding-top:39px}.studio-intro{margin:3px 0 29px}.studio-intro h1{font-size:39px;line-height:1.2;letter-spacing:-1.1px;margin:7px 0 10px;font-weight:600}.studio-intro p{font-size:16px;color:#5f6b66}
.start-layout{grid-template-columns:1.35fr 1fr;gap:0;border:1px solid #cfd7d0;border-radius:12px;overflow:hidden;background:#fff}
.practice-start{padding:28px 32px;min-height:276px;box-shadow:none;background:#fff;border:0;border-radius:0}
.practice-topline .small-label{color:#51615b}.practice-count{background:transparent;border:0;color:#5e6c64;padding:0;font-size:12px;white-space:nowrap}
.practice-copy{margin-top:21px}.practice-copy h2{font-size:31px;color:#263a3d;letter-spacing:-.65px;line-height:1.2;font-weight:600;max-width:480px}
.practice-copy p{font-size:15px;line-height:1.65;color:#5b6963;max-width:420px;margin-top:11px}.practice-start-actions{margin-top:24px;gap:18px}
.practice-start .start-button{background:#294851;border-color:#294851;color:#fff;border-radius:7px;min-height:48px;padding:11px 17px}.practice-start .start-button:hover{background:#193b43;border-color:#193b43}
.practice-start-actions>span{font-size:12px;color:#59685f}.practice-rule{display:none}
.home-model{border:0;border-left:1px solid #dce2dc;border-radius:0;box-shadow:none;background:#f8f9f5;padding:27px 29px;min-height:0}
.home-model .small-label{font-size:10px}.sample-topic{display:none}.home-model h3{font-size:21px;line-height:1.3;letter-spacing:-.4px;font-weight:550;max-width:270px;margin:20px 0}
.fraction-touch{height:41px;border-radius:4px;border-color:#8dacae}.fraction-touch button{min-height:41px;border-color:#a4bdbe}.fraction-touch button.shaded{background:#46737b}.same-amount{margin-top:18px;gap:12px}.same-amount b{color:#2e5861;font-size:24px;font-weight:550}.same-amount small{font-size:11px;color:#5f6d66}.same-amount i{color:#71867d}.model-instruction{font-size:12px;color:#5f6d66;margin-top:19px}
.section-top{margin:29px 0 15px}.section-top h2{font-size:20px;font-weight:550;letter-spacing:-.3px}
.practice-routes{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0;background:#fff;border:1px solid #d6ddd6;border-radius:10px;overflow:hidden}
.route-card{min-height:103px;border:0;border-bottom:1px solid #e2e7e1;border-radius:0;box-shadow:none;padding:22px;display:flex;align-items:center;gap:16px;background:transparent;position:relative;transform:none}
.route-card:nth-child(odd){border-right:1px solid #e2e7e1}.route-card:nth-last-child(-n+2){border-bottom:0}.route-card:hover{background:#f4f7f2;transform:none;box-shadow:none}
.route-symbol{height:34px;width:34px;min-width:34px;padding:0;background:transparent!important;border-radius:0;color:#4b6768;display:grid;place-items:center}.route-symbol .icon{width:24px;height:24px}
.route-copy{flex:1;min-width:0}.route-copy h3{font-size:19px;color:#2c3c3b;font-weight:550;letter-spacing:-.3px;margin-bottom:5px}.route-copy small{font-size:13px;line-height:1.5;color:#65716b;display:block;max-width:310px}.route-arrow{position:static;color:#687f74;align-self:center}.route-arrow .icon{width:18px;height:18px}
.home-record{border-color:#daddd7;font-size:12px;color:#626e68;margin-top:21px;padding-top:17px}.home-record .link-btn{font-size:12px}.studio-footer{border-color:#daddd7;margin-top:30px;color:#637069}
.page-intro{margin-bottom:24px}.page-intro h1{font-size:37px;font-weight:600;line-height:1.2;letter-spacing:-1px}.page-intro p{max-width:650px;font-size:15px;color:#5e6d65;line-height:1.65;margin-top:12px}
.practice-tabs{background:transparent;border:0;border-bottom:1px solid #cdd7cd;border-radius:0;padding:0;gap:8px;width:100%;margin-bottom:22px}
.practice-tabs button{border-radius:0;min-height:46px;padding:10px 16px;background:transparent;border-bottom:2px solid transparent;color:#5c6d64}.practice-tabs button[aria-current]{box-shadow:none;background:transparent;border-bottom-color:#294851;color:#294851;font-weight:650}
.search{background:#fff;border-color:#cbd6cd;border-radius:7px}.topic-grid{gap:12px}.topic-card{background:#fff;border-color:#d6ded5;border-radius:9px;box-shadow:none;padding:23px 21px}.topic-card:hover{background:#f9faf6;transform:none}.topic-card .tile-icon,.page-intro .tile-icon{background:#eef2ec!important;color:#436167;border-radius:6px}.topic-card h3{font-size:20px;line-height:1.3}.topic-card p{font-size:13px;color:#637268;line-height:1.6}
.skill-list{gap:0;border:1px solid #d6ded5;border-radius:9px;overflow:hidden;background:#fff}.skill-row{border:0;border-bottom:1px solid #e0e6de;border-radius:0;box-shadow:none;background:#fff;padding:19px 21px}.skill-row:last-child{border-bottom:0}.skill-row h3{font-size:18px;font-weight:550}.skill-row p{font-size:12px;color:#65756b}.skill-number{color:#647b70;background:transparent;font-variant-numeric:tabular-nums}.model-strip{border-radius:8px;background:#eaf0e8;border-color:#d1ddce}
.foundation-grid{gap:12px}.foundation-card{border-radius:9px;border-color:#d6ded5;box-shadow:none;padding:25px}.foundation-card:hover{box-shadow:none;transform:none;background:#f9fbf6}.foundation-symbol{background:#edf2e9;color:#43625f;border-radius:6px}.foundation-card h2{font-size:22px;font-weight:550}.foundation-card p{color:#65736a}.foundation-card-bottom{color:#4d6964}
.foundation-path>li>div{border-radius:9px;border-color:#d6ded5;box-shadow:none}.foundation-number{border-radius:6px;background:#e6eee2;color:#39564d}.foundation-path h2{font-weight:550}.foundation-path>li>div>.small-label{display:none}.foundation-help>button{border-radius:7px;border-color:#d0ddcd}.foundation-help>button>span:first-child{border-radius:5px;background:#edf3e8;color:#37594d}.foundation-help b{color:#2d413a}.foundation-help small{color:#5e7165}
.reasoning-card,.lab-menu-card{background:#fff;border-color:#d6ded5;border-radius:10px;box-shadow:none}.reasoning-card:hover,.lab-menu-card:hover{box-shadow:none;transform:none}.reasoning-card h3,.lab-menu-card h3{font-weight:550;font-size:24px}.reasoning-card-top>span:last-child{display:none}.reasoning-card-model{background:#f3f6ee!important;border-radius:6px}.reasoning-card p{color:#647169}.paper-card{border-color:#d6ded5;border-radius:9px;box-shadow:none}.paper-num{color:#3d5b58;background:#edf2e9;border-radius:5px}.paper-card h3{font-weight:550}.info-box{background:#edf2e9;border-color:#d6ded0;border-radius:8px}
body.learning{background:#f3f3ef}.player-top,.practice-divider{border-color:#d4dcd3}.practice-divider{background:#d4dcd3}.player-heading>span:first-child{color:#586d63}.player-heading b{font-weight:500}.player-heading .question-count{color:#53685e;font-variant-numeric:tabular-nums}
.model-toggle{border-radius:6px;background:#fff;border-color:#c9d5ca;color:#34594e;font-size:13px}.model-toggle:hover,.model-toggle[aria-expanded=false]{background:#e9f0e4;border-color:#aec1ad}.question-layout{border-color:#d1d9d0;border-radius:12px;box-shadow:0 2px 3px #21352203}
.question-card{padding:29px}.question-card h1{color:#233838;font-weight:550;line-height:1.42;letter-spacing:-.4px}.question-expression{color:#263f45;background:transparent;border:0;border-radius:0;padding:0;margin-top:22px;font-weight:500;line-height:1.45;font-variant-numeric:tabular-nums}
.question-visual{background:#fbfcf8;border-color:#e0e6db;border-radius:7px;margin-top:20px}.visual-label{color:#596d61;font-size:11px}.visual-label .link-btn{font-size:12px;min-height:44px;color:#365c60}.question-visual .model-table{border-color:#d4ddd0}.question-visual .model-table td,.question-visual .model-table th{border-color:#d4ddd0}.question-visual .model-table th{color:#3d554b;background:#f0f4eb}
.question-information{margin-top:18px;border-top:1px solid #dce5d7;flex-shrink:0}.question-information summary{min-height:44px;padding:11px 0;font-size:13px;color:#3c6155;cursor:pointer}.question-information p{font-size:14px;color:#4d6256;line-height:1.65;padding:0 0 12px;overflow-wrap:anywhere}
.answer-panel{background:#f6f8f2;border-color:#dce4d5;padding:25px}.answer-panel h2{color:#465f50;font-size:15px;font-weight:550}.answer-input{border-color:#a7bba9;border-radius:6px;font-weight:500;color:#213e34}.answer-input::placeholder{color:#637569}.pad-toggle{border-color:#c7d6c3;border-radius:6px;background:#edf3e7;color:#496d55}.choice{border-color:#c4d3bf;border-radius:6px;color:#2d473d}.choice.selected{background:#e7efe1;border-color:#617f62}.choice .choice-dot{border-color:#769371}.answer-action .button.full{border-radius:7px;background:#294851;border-color:#294851}.answer-action .button.success-action{background:#294851;border-color:#294851}.answer-confirmed{border-radius:6px;background:#e7efe1;color:#315f43}.feedback{border-radius:6px}.feedback strong{font-weight:550}.feedback p{font-size:14px;line-height:1.6}
.player-tools button,.exit-practice{color:#506b5e}.player-tools button:hover{background:#e8eee3}.screen-control{border-radius:6px;border-color:#d0dacb;color:#496759;background:#fff}.foundation-ribbon{background:#eaf1e3;border-color:#d5e0cc;border-radius:6px}.foundation-ribbon button{color:#4a6855}
 dialog,dialog.learning-dialog,dialog.model-viewer{background:#fbfcf8}.dialog-heading{border-color:#d9e2d2}.dialog-heading h2{font-weight:550;color:#2c4539}.dialog-heading .icon-btn{background:#edf3e6;color:#4f7055;border-radius:6px}.help-menu{border-color:#d8e2d0;border-radius:8px}.help-menu>button{border-color:#dfe7d8;background:#fff}.help-menu>button:hover{background:#f3f7ed}.help-menu b{font-weight:550;color:#2f4a3c}.help-menu small{color:#5b7261}.help-menu>button>.icon:first-child{color:#56785b}.viewer-viewport{background:#fff;border-color:#d9e3d1;border-radius:8px}.viewer-controls button{border-radius:6px;background:#edf3e7;border-color:#d3e0ca;color:#375d42}.viewer-description{background:#edf3e7;border-radius:6px}.viewer-description summary{color:#405f49}.viewer-head h2{color:#2f483a}.viewer-tip{color:#5c7261}.toggle[aria-checked=true]{background:#4a7356}
.high-contrast p,.high-contrast small,.high-contrast .route-copy small,.high-contrast .page-intro p,.high-contrast .practice-copy p,.high-contrast .foundation-card p{color:#243b2c}.high-contrast .practice-start-actions>span{color:#243b2c}.high-contrast .question-layout,.high-contrast .topic-card,.high-contrast .foundation-card,.high-contrast .choice,.high-contrast .question-visual{border-color:#657f62}.high-contrast .question-visual{background:#fff}
@media(max-width:1000px){.studio-nav .nav-item{font-size:12px;padding:10px 8px}.studio-header{gap:15px}.home-model{padding:26px 23px}.same-amount{gap:7px}}
@media(max-width:620px){
 .studio-header{padding:11px 18px;min-height:66px}.studio-main{padding:24px 18px 14px}.studio-intro{margin:4px 0 22px}.studio-intro h1{font-size:32px;margin:8px 0 10px;letter-spacing:-.9px}.studio-intro p{font-size:14px;line-height:1.6}
 .studio-nav{border:0;border-top:1px solid #d5ded0;border-radius:0;background:#fbfcf8;padding:6px 8px max(7px,env(safe-area-inset-bottom));gap:2px}.studio-nav .nav-item{padding:6px 4px;min-height:52px;font-size:11px;border-radius:6px;gap:5px}.studio-nav .nav-item .icon{width:20px;height:20px}.studio-nav .nav-item.active{background:#e7eee1}
 .start-layout{display:contents;border:0;background:transparent}.practice-start{padding:23px 22px;border:1px solid #cdd8c9;border-radius:9px;min-height:0}.practice-copy{margin-top:18px}.practice-copy h2{font-size:27px;line-height:1.25;letter-spacing:-.5px}.practice-copy p{font-size:14px;max-width:none;line-height:1.65}.practice-topline .small-label{font-size:10px}.practice-count{font-size:11px}.practice-start-actions{margin-top:21px;gap:14px}.practice-start-actions>span{font-size:11px}.practice-start .start-button{font-size:14px;min-height:48px;padding:10px 14px}
 .home-model{border:1px solid #d3ddcd;border-radius:9px;padding:23px;background:#f9fbf5;min-height:0}.home-model h3{font-size:21px;margin:15px 0 18px;max-width:none}.same-amount b{font-size:24px}.sample-fraction{font-size:20px}.model-instruction{font-size:12px}
 .section-top{margin:25px 0 12px}.section-top h2{font-size:19px}.practice-routes{grid-template-columns:1fr;border-radius:8px}.route-card{min-height:91px;padding:18px;gap:14px}.route-card:nth-child(odd){border-right:0}.route-card:nth-last-child(-n+2){border-bottom:1px solid #e2e7e1}.route-card:last-child{border-bottom:0}.route-symbol{width:27px;min-width:27px;height:27px}.route-symbol .icon{width:23px;height:23px}.route-copy h3{font-size:18px;margin-bottom:4px}.route-copy small{font-size:13px;line-height:1.45}.route-arrow{position:static}.home-record{font-size:12px}.home-record .icon{display:none}.studio-footer{font-size:11px;margin-top:25px}
 .page-intro h1{font-size:30px;letter-spacing:-.7px}.page-intro p{font-size:14px;line-height:1.6}.practice-tabs{margin-bottom:20px;gap:0}.practice-tabs button{min-height:46px;font-size:13px}.topic-card{padding:18px 16px}.topic-card h3{font-size:18px}.topic-card p{font-size:12px}.skill-row{padding:18px 15px}.skill-row h3{font-size:17px}.skill-row p{font-size:12px}.foundation-card{padding:20px 18px}.foundation-card h2{font-size:20px}.foundation-card p{font-size:13px}.foundation-card-bottom{font-size:12px}.foundation-path>li>div{padding:19px 17px}.foundation-path h2{font-size:22px}.reasoning-card h3{font-size:23px}
 .player{padding-left:12px;padding-right:12px}.player-heading{font-size:12px;gap:8px}.player-heading .question-count{font-size:12px}.model-toggle{font-size:12px;min-height:42px;padding:7px 10px;gap:6px}.question-layout{border-radius:10px}.question-card{padding:18px}.question-card h1{font-size:22px;line-height:1.42;letter-spacing:-.25px}.word-question h1{font-size:20px;line-height:1.43}.question-expression{font-size:34px;margin-top:16px;padding:0}.question-visual{padding:2px 9px 8px;border-radius:6px;margin-top:16px;min-height:145px}.visual-label{min-height:40px;font-size:10px;gap:8px}.visual-label .link-btn{font-size:11px;min-height:40px;gap:5px}.question-information{margin-top:13px}.question-information summary{font-size:12px}.question-information p{font-size:13px}
 .answer-panel{padding:13px 14px}.answer-panel h2{font-size:14px;margin-bottom:9px}.answer-input{font-size:24px;height:51px}.answer-input::placeholder{font-size:16px}.pad-toggle{width:37px;min-width:37px}.number-answer:not(.answer-done){grid-template-columns:minmax(0,1fr) 123px;gap:10px}.answer-action .button.full{font-size:13px;padding:10px 11px;min-height:49px}.number-answer .button[data-action="check"]{padding-inline:7px}.answer-panel .choice{font-size:15px;padding:10px;min-height:46px}.feedback p{font-size:13px;line-height:1.55}.player-tools button{font-size:12px;gap:6px}.exit-practice,.screen-control{font-size:12px}.large-text .word-question h1{font-size:25px}.large-text .question-card h1{font-size:27px}.large-text .number-answer:not(.answer-done){display:flex}.large-text .model-toggle{font-size:14px}
}
@media(max-width:360px){.studio-main{padding-left:15px;padding-right:15px}.studio-intro h1{font-size:29px}.practice-start{padding:21px 19px}.practice-copy h2{font-size:25px}.practice-start-actions{gap:10px}.practice-start-actions>span{font-size:10px}.player{padding-left:9px;padding-right:9px}.question-card{padding:14px}.word-question h1{font-size:19px}.answer-panel{padding:11px 10px}.number-answer:not(.answer-done){grid-template-columns:minmax(0,1fr) 110px;gap:7px}.answer-action .button.full{font-size:12px;padding:9px 7px}.player-tools button{font-size:11px}.visual-label{font-size:9px}.visual-label .link-btn{font-size:10px}}
@media(max-height:600px){.question-card{padding:13px}.question-card h1{font-size:20px}.word-question h1{font-size:18px}.question-expression{font-size:28px;margin-top:9px}.question-visual{min-height:130px;margin-top:10px}.answer-panel{padding:10px 12px}}

.route-card{flex-direction:row;text-align:left;justify-content:flex-start}
.route-copy h3{font-weight:500}.route-symbol{color:#496c69}.route-card .route-symbol .icon{color:#496c69}
.home-model{justify-content:flex-start}.home-model .sample-heading{margin-bottom:0}.home-model h3{max-width:none;margin:18px 0 20px;font-weight:500}.home-model .fraction-touch{margin:0 0 17px}.home-model .same-amount{margin-top:0}.home-model .model-instruction{margin-top:15px}
@media(min-width:621px){.practice-start{min-height:280px}.home-model .sample-heading{margin-bottom:0}.home-model h3{font-size:21px;margin:18px 0 22px}.home-model .same-amount{gap:11px}.home-model .model-instruction{margin-top:17px}.route-card{min-height:108px}}