@import url('/static/fonts.css');
:root{--paper:#f4f4ed;--white:#fff;--ink:#182b25;--muted:#737b72;--line:#e1e5db;--lime:#d8f36a;--green:#244d3d;--red:#b33c35;--r:20px;font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none}
*{box-sizing:border-box}body{margin:0}a{color:inherit;text-decoration:none}button,input,select,textarea{font:inherit}button,a,input,textarea,select{-webkit-tap-highlight-color:transparent}button,.btn{cursor:pointer;border:0;border-radius:12px;padding:13px 20px;font-weight:600;background:var(--ink);color:white;display:inline-flex;align-items:center;justify-content:center;gap:10px;line-height:1.3}button:hover,.btn:hover{filter:brightness(1.12)}button:disabled{opacity:.5;cursor:wait}.btn.lime,button.lime{background:var(--lime);color:var(--ink)}.btn.light,button.light{background:var(--white);color:var(--ink);border:1px solid var(--line)}.btn.ghost,button.ghost{background:transparent;color:var(--ink);border:1px solid var(--line)}.small{font-size:13px}.muted{color:var(--muted)}.eyebrow{font-size:11px;letter-spacing:1.5px;font-weight:700;text-transform:uppercase}.row{display:flex;align-items:center;gap:12px}.spread{justify-content:space-between}.wrap{flex-wrap:wrap}.stack{display:grid;gap:16px}.grid{display:grid;gap:20px}.grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}.grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}.card{padding:26px;background:var(--white);border:1px solid var(--line);border-radius:var(--r)}h1,h2,h3,p{margin-top:0}h1{font-size:38px;letter-spacing:-1.5px;line-height:1.12;margin-bottom:14px}h2{font-size:23px;letter-spacing:-.5px}h3{font-size:17px}p{line-height:1.65}label{display:grid;gap:8px;font-size:13px;font-weight:600}input,select,textarea{width:100%;border:1px solid #d5dbcf;border-radius:10px;padding:12px 14px;background:white;color:var(--ink);min-height:44px}textarea{resize:vertical;min-height:100px}input[type=checkbox]{width:18px;min-height:18px}label.check{display:flex;align-items:start;gap:10px;line-height:1.5;font-weight:400}input:focus,select:focus,textarea:focus{outline:2px solid var(--green);outline-offset:2px}:focus-visible{outline:3px solid #84aa38;outline-offset:3px}.tag{display:inline-flex;border-radius:7px;padding:6px 9px;background:#eff2e9;font-size:11px;font-weight:700;letter-spacing:.2px}.tag.green{background:#e8f4d7;color:#31551e}.tag.red{background:#fceae6;color:var(--red)}.error{background:#fff0eb;border:1px solid #edc4b8;padding:14px;border-radius:12px;color:#9b302a}.empty{text-align:center;padding:52px 20px;max-width:560px;margin:auto}.empty .mark{font-size:40px;margin-bottom:20px}.logo{font-size:22px;font-weight:800;letter-spacing:-1px;display:inline-flex;align-items:center;gap:8px}.logo b{background:var(--lime);border-radius:7px;padding:3px 6px;color:var(--ink)}.logo small{font-size:9px;letter-spacing:1px;display:block}.public{max-width:1280px;margin:auto;padding:0 40px}.topnav{height:100px;display:flex;align-items:center;justify-content:space-between}.toplinks{display:flex;gap:30px;font-size:14px}.hero{padding:65px 0 85px;display:grid;grid-template-columns:1.2fr 1fr;gap:70px;align-items:center}.hero h1{font-size:clamp(48px,5.7vw,78px);line-height:1.04;letter-spacing:-4px;margin:24px 0}.hero .accent{background:var(--lime);padding:0 8px;display:inline-block;transform:rotate(-2deg)}.hero p{max-width:420px;font-size:17px;color:#687367}.hero-art{background:var(--ink);color:white;min-height:460px;border-radius:32px;position:relative;overflow:hidden;display:grid;place-items:center}.graph{position:absolute;inset:0;background-image:linear-gradient(#ffffff09 1px,transparent 1px),linear-gradient(90deg,#ffffff09 1px,transparent 1px);background-size:38px 38px}.hero-equation{font-family:Georgia,serif;font-size:60px;font-style:italic;transform:rotate(-10deg);color:var(--lime);z-index:1}.art-note{position:absolute;background:#fffef5;color:var(--ink);padding:19px 24px;border-radius:12px;box-shadow:0 8px 25px #0002;font-size:13px}.art-note.top{left:24px;top:30px;transform:rotate(-5deg)}.art-note.bottom{right:24px;bottom:30px;transform:rotate(4deg)}.hero-art svg{position:absolute;inset:16%;width:70%;height:70%;opacity:.4}.section{padding:70px 0;border-top:1px solid var(--line)}.section-title{display:flex;justify-content:space-between;align-items:end;margin-bottom:30px}.section-title h2{font-size:36px;max-width:520px}.stepno{display:grid;place-items:center;width:42px;height:42px;border-radius:50%;background:var(--lime);margin-bottom:30px;font-weight:700}.price{font-size:40px;font-weight:700;letter-spacing:-2px;margin:26px 0 6px}.price small{font-size:15px;font-weight:400;letter-spacing:0}.plan.featured{background:var(--green);color:white}.plan ul{padding-left:20px;line-height:2;font-size:14px}.public-footer{padding:35px 0;display:flex;justify-content:space-between;color:var(--muted);font-size:13px}.auth-layout{min-height:100vh;display:grid;grid-template-columns:.85fr 1.15fr}.auth-brand{background:var(--ink);color:white;padding:60px;display:flex;flex-direction:column;justify-content:space-between}.auth-brand h1{font-size:58px;max-width:460px}.auth-brand .logo{color:white}.auth-form{max-width:470px;width:100%;margin:auto;padding:40px}.auth-form h1{font-size:32px}.auth-form form{display:grid;gap:17px}.auth-form .under{margin-top:22px;font-size:13px;text-align:center}.auth-form .under a{text-decoration:underline}.shell{display:grid;grid-template-columns:242px minmax(0,1fr);min-height:100vh}.sidebar{background:#fbfcf7;border-right:1px solid var(--line);height:100vh;position:sticky;top:0;padding:32px 20px;display:flex;flex-direction:column;gap:34px}.sidebar .logo{margin:0 12px}.nav{display:grid;gap:5px}.nav a{display:flex;align-items:center;gap:13px;padding:13px 14px;border-radius:10px;font-size:13px;font-weight:500;color:#667368}.nav a.active{color:var(--ink);background:var(--lime);font-weight:700}.nav a:hover{background:#edf1e4}.nav .symbol{font-size:18px;width:22px;text-align:center}.sidebar-bottom{margin-top:auto;border-top:1px solid var(--line);padding-top:20px}.avatar{border-radius:50%;width:36px;height:36px;background:#dce7ce;display:grid;place-items:center;font-weight:bold}.main{padding:0 42px 60px;max-width:1580px;width:100%;margin:auto}.appbar{height:86px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;font-size:12px;color:var(--muted);margin-bottom:38px}.appbar button{font-size:12px;padding:9px 12px}.pagehead{display:flex;align-items:start;justify-content:space-between;gap:20px;margin-bottom:28px}.pagehead h1{font-size:32px}.pagehead p{color:var(--muted);font-size:14px;max-width:650px;margin:0}.welcome{background:var(--green);color:#fff;border:0;position:relative;overflow:hidden;padding:35px}.welcome h2{font-size:30px;max-width:470px;margin:14px 0}.welcome p{max-width:420px;color:#d8e3d6;font-size:14px}.welcome .tag{background:#ffffff18;color:var(--lime)}.welcome:after{content:'∑';position:absolute;right:40px;top:0;font:180px Georgia;color:#d8f36a22;pointer-events:none}.stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px;margin:22px 0}.stat{padding:22px}.stat strong{display:block;font-size:32px;letter-spacing:-1px;margin:14px 0 6px}.stat .small{font-size:12px}.stat.lime{background:var(--lime);border-color:var(--lime)}.sectionnums{display:grid;grid-template-columns:repeat(10,1fr);gap:8px;margin:22px 0}.sectionnums button{border:1px solid var(--line);padding:13px 8px;background:#fff;color:var(--ink);border-radius:10px}.sectionnums button.selected{background:var(--ink);color:var(--lime)}.toolbar{display:flex;gap:12px;align-items:center;margin-bottom:22px}.toolbar input{max-width:350px}.tabs{display:flex;gap:5px;padding:5px;background:#e9eddf;border-radius:12px;width:max-content;max-width:100%;overflow:auto}.tabs button{background:transparent;color:var(--muted);font-size:13px;padding:10px 17px;white-space:nowrap}.tabs button.selected{background:#fff;color:var(--ink);box-shadow:0 1px 4px #0001}.taskcard{padding:22px;display:flex;flex-direction:column;gap:18px;min-height:175px}.taskcard h3{line-height:1.4;margin:0}.taskcard .row:last-child{margin-top:auto}.taskcard.locked{background:#f7f8f2}.taskcard button{padding:9px 14px;font-size:12px}.tasktitle{font-family:Georgia,serif;font-size:32px}.exercise{font-size:19px;line-height:1.9;max-width:900px}.exercise img{max-width:100%;max-height:400px;display:block;object-fit:contain;margin:24px auto}.exercise .katex-display{overflow-x:auto;overflow-y:hidden;padding:8px 0}.mathtext{overflow-wrap:anywhere}.solution{padding-top:22px;border-top:1px solid var(--line);margin-top:24px}.answerbox{background:#f3f6ea;border:1px solid #dbe3ce;border-radius:14px;padding:22px;margin-top:28px}.answerbox input[type=text]{font-size:19px;max-width:320px}.timer{font-variant-numeric:tabular-nums;font-size:13px;background:#edf2e3;padding:10px 13px;border-radius:10px}.link{text-decoration:underline;cursor:pointer}.workrow{display:flex;align-items:center;justify-content:space-between;gap:16px;border-bottom:1px solid var(--line);padding:19px 0}.workrow:last-child{border:0}.workrow h3{margin:5px 0}.bar{height:7px;border-radius:9px;background:#edf0e6;overflow:hidden}.bar span{display:block;background:#8fae45;height:100%}.progressrows{display:grid;gap:18px}.progressrow{display:grid;grid-template-columns:80px minmax(0,1fr) 60px;gap:14px;align-items:center;font-size:12px}.player{width:100%;aspect-ratio:16/9;border:0;background:#12231c;border-radius:15px;min-width:320px;display:block}.video-cover{height:140px;background:#e7eddb;display:grid;place-items:center;position:relative;border-radius:12px;margin-bottom:18px}.video-cover .play{width:52px;height:52px;display:grid;place-items:center;background:var(--ink);color:var(--lime);border-radius:50%;font-size:20px}.video-cover .eyebrow{position:absolute;left:14px;top:14px;color:#647251}.videocard h3{margin:12px 0}.videocard .btn{width:100%;margin-top:15px}.notice{padding:16px 18px;background:#edf1e3;border-radius:12px;font-size:13px;line-height:1.6}.message{padding:15px 18px;border:1px solid var(--line);border-radius:15px;max-width:80%;background:#fff}.message.staff{background:#e6eedb;margin-left:auto}.message p{margin:0;white-space:pre-wrap}.message time{display:block;color:var(--muted);font-size:11px;margin-top:9px}.tablewrap{overflow:auto}table{width:100%;border-collapse:collapse;font-size:13px}th{text-align:left;color:var(--muted);font-weight:500;font-size:11px;text-transform:uppercase;letter-spacing:.5px;padding:14px 10px;border-bottom:1px solid var(--line)}td{padding:18px 10px;border-bottom:1px solid var(--line)}tr:last-child td{border:0}td button{padding:7px 12px;font-size:12px}.dialog-backdrop{position:fixed;inset:0;background:#10241c88;z-index:10;display:grid;place-items:center;padding:20px;overflow:auto}.dialog{max-width:650px;width:100%;max-height:90vh;overflow:auto;background:var(--paper);border-radius:20px;padding:30px}.dialog form{display:grid;gap:18px}.dialog .grid{gap:15px}.files{display:flex;gap:12px;flex-wrap:wrap;margin:15px 0}.files a{border:1px solid var(--line);padding:12px;border-radius:10px}.files img{max-width:200px;max-height:180px;object-fit:contain}#toast{position:fixed;bottom:25px;right:25px;max-width:400px;background:var(--ink);color:white;border-radius:12px;padding:16px 22px;box-shadow:0 5px 30px #0002;z-index:30;display:none}.initial{min-height:100vh;display:grid;place-content:center;font-size:45px}.initial p{font-size:14px}.loading{padding:60px;text-align:center;color:var(--muted)}.mobile-menu{display:none}.auth-error:empty{display:none}.back{font-size:12px;color:var(--muted);display:block;margin-bottom:20px}.good{color:#3a741f}.bad{color:var(--red)}.statusline{font-size:14px;font-weight:600}.footnote{font-size:12px;color:var(--muted);line-height:1.7;margin-top:18px}.num{font-variant-numeric:tabular-nums}.video-admin{margin-bottom:20px}.form-actions{display:flex;gap:10px;justify-content:end;flex-wrap:wrap}
@media(min-width:1500px){.main{padding-left:65px;padding-right:65px}.hero{gap:100px}}
@media(max-width:1100px){.shell{grid-template-columns:205px minmax(0,1fr)}.sidebar{padding:30px 12px}.main{padding:0 24px 40px}.stats{grid-template-columns:repeat(2,1fr)}.grid.three{grid-template-columns:repeat(2,minmax(0,1fr))}.hero{gap:25px}.hero h1{font-size:56px}.auth-brand{padding:35px}.auth-brand h1{font-size:46px}}
@media(max-width:760px){.public{padding:0 22px}.topnav{height:80px}.toplinks{display:none}.hero{grid-template-columns:1fr;padding:30px 0 50px;gap:35px}.hero h1{font-size:51px;letter-spacing:-2.8px}.hero-art{min-height:330px}.section{padding:44px 0}.section-title h2{font-size:28px}.grid.two,.grid.three{grid-template-columns:1fr}.public-footer{flex-direction:column;gap:18px}.auth-layout{display:block}.auth-brand{min-height:0;padding:25px}.auth-brand h1,.auth-brand p{display:none}.auth-form{padding:32px 24px}.shell{display:block}.sidebar{display:none;position:fixed;width:260px;z-index:20;box-shadow:20px 0 100px #0003}.sidebar.open{display:flex}.main{padding:0 18px 40px}.appbar{height:70px;margin-bottom:28px}.mobile-menu{display:inline-flex}.appbar>.eyebrow{display:none}.pagehead{flex-wrap:wrap}.pagehead h1{font-size:29px}.pagehead .row{flex-wrap:wrap}.card{padding:21px}.sectionnums{grid-template-columns:repeat(5,1fr);gap:7px}.toolbar{flex-wrap:wrap}.toolbar input{max-width:none}.exercise{font-size:17px}.player{width:calc(100% + 2px);border-radius:7px}.stats{gap:10px}.stat{padding:18px}.stat strong{font-size:27px}.welcome{padding:25px}.welcome:after{right:15px;font-size:150px}.welcome h2{font-size:26px}.workrow{flex-wrap:wrap}.dialog-backdrop{padding:10px}.dialog{padding:23px}.dialog .grid.two{grid-template-columns:1fr}.message{max-width:95%}.section-title{display:block}.section-title p{margin-bottom:0}.hero .row{flex-wrap:wrap}.progressrow{grid-template-columns:70px minmax(0,1fr) 45px;gap:9px}.video-page{margin-left:-2px;margin-right:-2px}.video-page .card{padding:0;border:0;background:transparent}.tablewrap{margin:0 -10px}.taskcard{min-height:160px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}