:root{color-scheme:light;--primary:#2458a6;--on-primary:#fff;--primary-container:#d9e6ff;--on-container:#14335d;--surface:#f8f9ff;--surface-container:#edf1fa;--surface-high:#e5ebf6;--ink:#1b1b20;--muted:#545e70;--outline:#747f91;--line:#d4dae6;--success:#236444;--error:#a53432;--app-height:100dvh;font:16px/1.5 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}*{box-sizing:border-box}body{margin:0;background:var(--surface);color:var(--ink)}button,input,select,textarea{font:inherit}button,a,input,select,textarea{-webkit-tap-highlight-color:transparent}button{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:44px;padding:10px 24px;border:1px solid transparent;border-radius:999px;background:var(--primary);color:var(--on-primary);font-size:14px;font-weight:650;cursor:pointer;transition:background .15s,box-shadow .15s}button:hover{box-shadow:0 2px 7px #16315a25;filter:brightness(.97)}button:disabled{opacity:.45;cursor:default;box-shadow:none}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid var(--primary);outline-offset:3px}.tonal{background:var(--primary-container);color:var(--on-container)}.outlined{border-color:var(--outline);background:transparent;color:var(--primary)}.text-button{background:transparent;color:var(--primary);padding:10px 14px}.icon-button{background:transparent;color:var(--muted);padding:8px;min-width:44px;font-size:20px}a{color:var(--primary);text-underline-offset:3px}.app-bar{height:80px;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px max(24px,env(safe-area-inset-left));border-bottom:1px solid var(--line);background:var(--surface);flex:none}.brand{display:flex;align-items:center;gap:10px;color:var(--ink);font-size:21px;font-weight:700;text-decoration:none;letter-spacing:-.5px}.brand small{display:block;font-size:11px;font-weight:500;color:var(--muted);letter-spacing:.4px}.brand-mark{display:flex;align-items:center;justify-content:center;background:var(--primary);color:#fff;border-radius:14px;width:42px;height:42px;font-size:25px}.brand-mark span{font-size:17px;color:#c8dbff;align-self:flex-start;padding-top:4px}.app-bar nav{display:flex;gap:8px;align-items:center}.nav-link{padding:10px 14px;font-size:14px;font-weight:600;text-decoration:none;border-radius:24px}.nav-link:hover{background:var(--surface-container)}main{max-width:1040px;margin:0 auto;padding:44px 28px 64px}.view{animation:enter .16s ease-out}h1{font-size:clamp(30px,4vw,44px);line-height:1.18;letter-spacing:-1.1px;font-weight:550;margin:12px 0 16px}h2{font-size:24px;font-weight:550;line-height:1.3;margin:0 0 14px}h3{font-size:17px;font-weight:650;margin:0 0 8px}p{margin:12px 0;max-width:72ch}.eyebrow{font-size:12px;color:var(--primary);letter-spacing:1.1px;font-weight:650;text-transform:uppercase}.muted{font-size:13px;color:var(--muted)}.surface{padding:28px;background:#fff;border:1px solid var(--line);border-radius:24px;margin:20px 0}.home-heading>p{color:var(--muted);font-size:18px}.activities{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin:32px 0}.activity{position:relative;display:flex;flex-direction:column;align-items:flex-start;justify-content:flex-start;gap:12px;padding:24px;background:var(--surface-container);color:var(--ink);border:2px solid transparent;border-radius:24px;text-align:left;font-weight:400}.activity strong{font-size:18px;font-weight:600}.activity>span:not(.activity-icon):not(.activity-check){font-size:14px;color:var(--muted)}.activity[aria-pressed=true]{background:var(--primary-container);border-color:var(--primary)}.activity-icon{width:44px;height:44px;border-radius:14px;background:#ffffff9c;display:grid;place-items:center;color:var(--primary);font-size:25px}.activity-check{position:absolute;right:20px;top:24px;color:var(--primary);font-size:20px;font-weight:700}.fields{display:grid;grid-template-columns:1fr 1fr;gap:24px}label{display:block;font-size:14px;font-weight:600;margin:12px 0 7px}input:not([type=checkbox]),select,textarea{width:100%;min-height:52px;padding:12px 15px;color:var(--ink);border:1px solid var(--outline);border-radius:10px;background:#fff}input[type=number]{max-width:150px}input[type=password]{max-width:440px}textarea{resize:vertical;min-height:150px}form>button{margin-top:20px}.actions{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin:20px 0 8px}.auth-card{max-width:580px;margin:24px auto;background:#fff;border:1px solid var(--line);border-radius:28px;padding:36px}.auth-card form{margin-top:28px}.auth-card form>button{display:flex}.notice,.resume-bar{background:var(--primary-container);border-radius:16px;color:var(--on-container);padding:16px 20px;margin:16px 0}.resume-bar{display:flex;align-items:center;justify-content:space-between;gap:12px}.page-title{display:flex;align-items:center;justify-content:space-between;gap:16px}.page-title h1{max-width:600px}fieldset{border:1px solid var(--line);border-radius:16px;padding:16px 20px;margin:20px 0}legend{font-size:14px;font-weight:650;padding:0 8px}.check-label{display:flex;align-items:center;gap:12px;min-height:44px;margin:0;font-weight:450}.check-label input{width:20px;height:20px;accent-color:var(--primary);flex:none}details{padding:18px 0;border-bottom:1px solid var(--line)}details.surface{padding:24px}summary{cursor:pointer;font-weight:600}.recap-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin:28px 0}.recap-stats>div{padding:24px;border-radius:20px;background:var(--primary-container);color:var(--on-container)}.recap-stats strong{font-size:32px;display:block}.recap-stats span{font-size:13px}.notebook-notes{white-space:pre-wrap}.loading{padding:40px;text-align:center;color:var(--muted)}
/* The problem workspace uses the visible viewport; only long content scrolls. */
body.in-practice{height:var(--app-height);display:flex;flex-direction:column;overflow:hidden}.in-practice main{width:100%;flex:1;min-height:0;padding:20px 28px 16px;display:flex;flex-direction:column}.practice-view{flex:1;min-height:0;display:flex;flex-direction:column;gap:12px;max-width:820px;width:100%;margin:0 auto}.practice-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;flex:none}.practice-heading h1{font-size:20px;line-height:1.2;letter-spacing:-.3px;margin:3px 0 0}.question-count{font-size:24px;font-weight:600;color:var(--primary);white-space:nowrap}.question-count span{font-size:15px;color:var(--muted);font-weight:400}progress{width:100%;height:5px;flex:none;border:0;border-radius:4px;accent-color:var(--primary);overflow:hidden}progress::-webkit-progress-bar{background:var(--surface-high)}progress::-webkit-progress-value{background:var(--primary)}.problem-card{min-height:0;flex:1;display:flex;flex-direction:column;padding:24px 28px 20px;border:1px solid var(--line);border-radius:24px;background:#fff}.problem-scroll{overflow:auto;min-height:60px;flex:1;overscroll-behavior:contain}.chip{display:inline-flex;padding:4px 12px;border-radius:8px;background:var(--surface-container);color:var(--muted);font-size:12px}.problem{font-size:clamp(20px,2.6vw,28px);line-height:1.4;font-weight:500;margin:16px 0 20px;max-width:100%}#answer-form{flex:none}#answer-form label{margin-top:8px}.answer-row{display:flex;gap:12px}.answer-row input{min-width:0;flex:1}.answer-row button{flex:none;margin:0}#number-help{margin:5px 0 0;font-size:12px}.feedback{height:52px;min-height:52px;margin:8px 0 0;font-size:14px;font-weight:550;line-height:1.4;overflow:auto;display:flex;align-items:center}.feedback[data-kind=success]{color:var(--success)}.feedback[data-kind=retry],.feedback[data-kind=error]{color:var(--error)}.tools{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;flex:none}.tools button{padding:10px 8px;white-space:nowrap}.question-nav{display:flex;align-items:center;justify-content:space-between;gap:8px;flex:none;padding-bottom:env(safe-area-inset-bottom)}.nav-actions{display:flex;gap:10px}.nav-actions .outlined{min-width:44px;padding:8px 14px}.question-nav button{white-space:nowrap}.in-practice .app-bar{height:64px}
dialog{border:0;border-radius:28px;padding:0;background:var(--surface);color:var(--ink);width:min(560px,calc(100% - 40px));max-height:calc(var(--app-height) - 48px);box-shadow:0 20px 60px #172b5040;overflow:hidden}dialog[open]{display:flex;flex-direction:column}dialog::backdrop{background:#15223c80;backdrop-filter:blur(2px)}.dialog-header{display:flex;justify-content:space-between;align-items:center;padding:16px 20px 8px;gap:16px;flex:none}.dialog-header h2{margin:0;font-size:22px}.dialog-content{padding:12px 24px 24px;overflow:auto;overscroll-behavior:contain;min-height:0}.dialog-content p:first-child{margin-top:0}.hint-card,.explanation{border-radius:16px;background:var(--primary-container);padding:20px;margin:0 0 16px;line-height:1.65;color:var(--on-container)}.dialog-problem{font-weight:600}.dialog-content code{overflow-wrap:anywhere}code{font-size:.9em;overflow-wrap:anywhere}#update-banner{padding:8px 24px;background:var(--primary-container);text-align:center;font-size:14px}#update-banner[hidden]{display:none}#parent-status,#home-status,#connection-status,#access-status{white-space:pre-wrap;overflow-wrap:anywhere}#parent-status:empty,#home-status:empty,#connection-status:empty,#access-status:empty{display:none}
@keyframes enter{from{opacity:.5;transform:translateY(4px)}to{opacity:1;transform:none}}
@media(max-width:700px){.app-bar{height:68px;padding:10px 16px}.app-bar nav{gap:0}.brand{font-size:18px}.brand-mark{width:36px;height:36px;border-radius:12px}.nav-link{font-size:12px;padding:10px}.app-bar .text-button{font-size:12px;padding:10px}.brand small{font-size:10px}main{padding:28px 16px 40px}.activities{grid-template-columns:1fr;gap:10px;margin:24px 0}.activity{padding:18px 20px;gap:6px}.activity-icon{width:36px;height:36px;font-size:22px}.activity strong{font-size:17px}.activity-check{top:24px}.fields{grid-template-columns:1fr;gap:4px}.surface{padding:20px;border-radius:20px}.auth-card{padding:24px;margin:12px 0}.page-title{align-items:flex-start;flex-direction:column;gap:0}.recap-stats{gap:8px}.recap-stats>div{padding:16px 10px}.recap-stats span{font-size:12px}.resume-bar{align-items:flex-start;flex-direction:column}.in-practice .app-bar{height:56px}.in-practice main{padding:10px 12px 8px}.practice-view{gap:8px}.practice-heading h1{font-size:16px}.practice-heading .eyebrow{font-size:10px;letter-spacing:.7px}.question-count{font-size:21px}.problem-card{padding:16px;border-radius:20px}.problem{font-size:21px;margin:12px 0}.chip{font-size:11px;padding:3px 10px}.answer-row{gap:8px}.answer-row input{min-height:48px;padding:10px 12px}.answer-row button{padding:10px 18px}#number-help{font-size:11px;line-height:1.35}.feedback{font-size:13px;height:48px;min-height:48px;margin-top:4px}.tools{gap:6px}.tools button{font-size:12px;padding:10px 4px}.question-nav .text-button{padding:10px 6px;font-size:13px}.question-nav #next{padding:10px 18px}.nav-actions{gap:6px}.wide-label{display:none}#overlay{width:100%;max-width:none;height:var(--app-height);max-height:var(--app-height);margin:0;border-radius:0;padding-top:env(safe-area-inset-top);padding-bottom:env(safe-area-inset-bottom)}#overlay .dialog-header{padding:12px 16px 8px}#overlay .dialog-content{padding:16px 20px 24px;flex:1}#reconnect{width:calc(100% - 24px)}#reconnect .dialog-content{padding:24px}}
@media(max-height:560px){.in-practice .app-bar{height:48px}.in-practice main{padding-top:6px}.practice-view{gap:6px}.problem-card{padding:10px 14px}.problem{font-size:18px;margin:4px 0 10px}.feedback{height:38px;min-height:38px;font-size:12px}.practice-heading h1{font-size:15px}.tools button{min-height:38px;padding:6px}.question-nav button{min-height:40px;padding-top:8px;padding-bottom:8px}.answer-row input{min-height:44px}.problem-scroll{min-height:40px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important}}
@media print{.app-bar,#update-banner,button,dialog,.actions{display:none!important}body{background:#fff}main{max-width:none;padding:0}.surface{border:0;padding:0}.recap-stats>div{background:#fff;border:1px solid #ccc}details{break-inside:avoid}}
/* Safari keeps its layout viewport tall and pans the visual viewport for input.
   Anchor answer entry to the visible area, independently of page scrolling. */
@media(max-width:700px){
 body.in-practice.answer-entry{position:fixed;top:var(--viewport-top,0px);left:0;right:0;width:100%;height:var(--app-height);}
 .answer-entry .app-bar,.answer-entry .practice-heading,.answer-entry progress,.answer-entry .question-nav,.answer-entry .chip{display:none}
 .answer-entry main{padding:8px 12px!important;max-height:100%;}
 .answer-entry .practice-view{gap:0;}
 .answer-entry .problem-card{padding:12px 16px;overflow:auto;}
 .answer-entry .problem-scroll{flex:1;min-height:64px;}
 .answer-entry .problem{font-size:20px;line-height:1.35;margin:4px 0 12px;}
 .answer-entry #answer-form{flex:none;}
 .answer-entry .answer-row input{font-size:16px;}
 .answer-entry .feedback:empty{height:0;min-height:0;margin:0;}
}

@media(max-width:700px){.answer-entry .tools{display:grid;margin-top:8px;gap:6px}.answer-entry .tools button{min-height:44px;padding:8px 4px}}
/* Session selection starts with the activities and keeps the setup compact. */
.session-selection main{padding-top:16px;padding-bottom:16px}
.session-selection .activities{margin:0 0 12px}
.session-selection .surface{margin:0;padding:20px}
.session-selection .resume-bar{margin:0 0 12px;padding:8px 12px}
@media(max-width:700px){
 .session-selection main{padding:12px}
 .session-selection .activities{gap:8px}
 .session-selection .activity{display:grid;grid-template-columns:32px 1fr;column-gap:12px;row-gap:2px;padding:10px 28px 10px 12px;border-radius:16px}
 .session-selection .activity-icon{grid-row:1 / 3;width:32px;height:32px;align-self:center}
 .session-selection .activity strong{font-size:15px;line-height:1.3}
 .session-selection .activity>span:not(.activity-icon):not(.activity-check){font-size:12px;line-height:1.35}
 .session-selection .activity-check{top:12px;right:10px;font-size:16px}
 .session-selection .surface{padding:12px 16px;border-radius:16px}
 .session-selection .fields{gap:0}
 .session-selection label{margin:4px 0;font-size:13px}
 .session-selection select{min-height:44px;padding:8px 12px}
 .session-selection .muted{margin:4px 0 8px;font-size:12px}
 .session-selection .actions{margin:4px 0 0}
 .session-selection .resume-bar{font-size:12px;flex-direction:row;align-items:center}
}
/* Session cards and the school-lesson picker share the same status language. */
body.session-selection{background:linear-gradient(150deg,#eef4fd,#f8f9ff)}
.session-selection main{max-width:700px;width:100%;padding:24px 24px 32px}
.session-selection .activities{display:grid;grid-template-columns:1fr;gap:12px;margin:0 0 20px}
.session-selection .activity{display:grid;grid-template-columns:44px minmax(0,1fr) 26px;align-items:center;column-gap:16px;row-gap:2px;min-height:80px;padding:16px 20px;border:1px solid var(--line);border-radius:16px;background:#fff;box-shadow:0 2px 4px #18365c06}
.session-selection .activity[aria-pressed=true]{background:#e9f1ff;border:2px solid var(--primary);padding:15px 19px}
.session-selection .activity-icon{grid-column:1;grid-row:1 / 3;width:44px;height:44px;border-radius:12px;background:#e1ecff;align-self:center}
.activity-icon svg{width:26px;height:26px}
.session-selection .activity strong{grid-column:2;font-size:20px;line-height:1.3}
.session-selection .activity>span.activity-paused{grid-column:2;font-size:12px;color:var(--muted)}
.session-selection .activity-check{position:static;grid-column:3;grid-row:1 / 3;display:grid;place-items:center;width:26px;height:26px;border-radius:50%;font-size:16px}
.session-selection .activity[aria-pressed=true] .activity-check{color:#fff;background:var(--primary)}
.session-selection .session-setup{padding:24px;border:1px solid #e5eaf3;box-shadow:0 4px 16px #18365c06;border-radius:22px}
.session-selection .fields{display:block}
.session-selection .fields>div+div{margin-top:16px}
.session-selection label{font-size:15px;margin:0 0 8px}
.topic-trigger{width:100%;min-height:76px;padding:12px 16px;justify-content:space-between;gap:12px;border:1px solid var(--outline);border-radius:12px;background:#fff;color:var(--ink);text-align:left;font-size:17px;font-weight:500;line-height:1.35}
.topic-value{display:flex;flex-direction:column;align-items:flex-start;gap:5px;min-width:0}
.topic-chevron{flex:none;font-size:26px;line-height:1}
.lesson-badge{display:inline-block;font-size:11px;line-height:1.4;border:1px solid #8a96a8;border-radius:5px;padding:0 6px;color:var(--muted);font-weight:600}
.lesson-badge[data-status=current]{color:var(--primary);border-color:#7d9ed0;background:#f5f9ff}
.lesson-badge[data-status=completed]{color:var(--success);border-color:#9bbba5;background:#f1f7f2}
.session-selection #example{margin:6px 0 0;font-size:12px}
.session-selection .session-meta{margin:8px 0 0}
.session-selection .actions{margin:20px 0 0;flex-wrap:nowrap}
.session-selection #start{flex:1;border-radius:12px;font-size:16px;min-height:48px}
.session-selection #student-logout{padding:10px 6px}
#home-status:empty{display:none}
#overlay[data-kind=lessons]{width:min(640px,calc(100% - 32px));max-height:calc(100dvh - 48px);border-radius:24px;padding:0;overflow:hidden}
#overlay[data-kind=lessons] .dialog-header{padding:20px 24px 4px;flex:none;border:0}
#overlay[data-kind=lessons] .dialog-content{padding:0 24px 24px;overflow-y:auto;overscroll-behavior:contain}
.picker-subtitle{margin:0 0 16px;color:var(--muted);font-size:14px}
.lesson-group{border-top:1px solid var(--line);padding:16px 0;margin:0}
.lesson-group h3,.lesson-group summary{font-size:12px;line-height:1.5;font-weight:700;color:var(--muted);text-transform:uppercase;letter-spacing:.6px;margin:0 0 10px}
.lesson-group summary{cursor:pointer;min-height:44px;display:flex;align-items:center;justify-content:space-between;margin:-8px 0 0;list-style:none}
.lesson-group summary::-webkit-details-marker{display:none}
.lesson-group summary::after{content:'⌄';font-size:22px}
.lesson-group:not([open]) summary::after{content:'›'}
.lesson-option{width:100%;display:grid;grid-template-columns:22px minmax(0,1fr);gap:2px 12px;justify-content:start;align-items:center;border:1px solid var(--line);border-radius:12px;background:#fff;color:var(--ink);padding:12px 14px;text-align:left;margin:0 0 8px;min-height:64px;line-height:1.35;box-shadow:none}
.lesson-option:last-child{margin-bottom:0}
.lesson-radio{grid-column:1;grid-row:1 / 3;width:20px;height:20px;border:2px solid #707a88;border-radius:50%;display:grid;place-items:center}
.lesson-name{grid-column:2;font-size:14px;font-weight:650;overflow-wrap:anywhere}
.lesson-status{grid-column:2;display:flex;align-items:center;gap:5px;color:var(--muted);font-size:12px;font-weight:500}
.lesson-option.completed{background:#f1f6f3}
.lesson-option.completed .lesson-status{color:var(--success)}
.completed-check{display:inline-grid;place-items:center;border:1px solid currentColor;border-radius:50%;width:14px;height:14px;font-size:10px}
.lesson-option[aria-pressed=true]{background:#e3edff;border-color:#7b9ed7}
.lesson-option[aria-pressed=true] .lesson-radio{border-color:var(--primary)}
.lesson-option[aria-pressed=true] .lesson-radio::after{content:'';width:10px;height:10px;background:var(--primary);border-radius:50%}
.lesson-option.current .lesson-status{color:var(--primary)}
.picker-note{font-size:12px;color:var(--muted);margin:0 0 18px}
@media(max-width:700px){
 .session-selection main{padding:12px}
 .session-selection .activities{gap:8px;margin-bottom:12px}
 .session-selection .activity{grid-template-columns:36px minmax(0,1fr) 24px;column-gap:12px;min-height:60px;padding:10px 12px;border-radius:14px}
 .session-selection .activity[aria-pressed=true]{padding:9px 11px}
 .session-selection .activity-icon{width:36px;height:36px;border-radius:10px}
 .session-selection .activity strong{font-size:16px}
 .session-selection .activity-check{width:24px;height:24px}
 .session-selection .session-setup{padding:16px;border-radius:18px}
 .session-selection .fields>div+div{margin-top:12px}
 .session-selection label{font-size:14px;margin:0 0 6px}
 .topic-trigger{min-height:70px;font-size:15px;padding:10px 12px}
 .session-selection .muted{font-size:11px;margin:6px 0 0}
 .session-selection .actions{margin-top:14px}
 .session-selection #start{font-size:15px;min-height:46px}
 #overlay[data-kind=lessons]{width:100%;max-width:none;max-height:calc(var(--app-height) - 24px);height:auto;margin:24px 0 0;border-radius:22px 22px 0 0;align-self:end;position:fixed;top:auto;bottom:0;padding-top:0;padding-bottom:env(safe-area-inset-bottom)}
 #overlay[data-kind=lessons] .dialog-header{padding:14px 16px 4px}
 #overlay[data-kind=lessons] .dialog-header h2{font-size:23px}
 #overlay[data-kind=lessons] .dialog-content{padding:0 16px 24px}
 .picker-subtitle{font-size:12px;margin-bottom:12px}
 .lesson-group{padding:12px 0}
 .lesson-option{padding:10px 12px;column-gap:10px;min-height:64px}
 .lesson-name{font-size:13px}
}