:root{color-scheme:light;--page: #f5f7fb;--surface: #ffffff;--surface-soft: #f8fafc;--ink: #172033;--ink-soft: #64748b;--mist: #94a3b8;--line: #e2e8f0;--line-strong: #cbd5e1;--primary: #2563eb;--primary-dark: #1d4ed8;--primary-soft: #eff6ff;--success: #15803d;--success-soft: #f0fdf4;--warning: #b45309;--warning-soft: #fffbeb;--danger: #dc2626;--danger-soft: #fef2f2;--brand-red: #a53b2d;--shadow-sm: 0 1px 2px rgba(15, 23, 42, .04);--shadow: 0 12px 32px rgba(15, 23, 42, .07);--radius: 12px;--radius-lg: 18px;font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Microsoft 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var(--line);background:var(--surface)}.login-intro:after{content:"";width:520px;height:520px;position:absolute;right:-250px;bottom:-290px;border-radius:50%;background:#eff6ff}.login-copy{max-width:650px;margin:auto 0;position:relative;z-index:1}.login-kicker{display:inline-flex;margin-bottom:20px;padding:6px 10px;border-radius:999px;color:var(--primary);background:var(--primary-soft);font-size:.76rem;font-weight:700}.login-copy h1{margin-bottom:20px;font-size:clamp(2.35rem,4.5vw,4rem);line-height:1.14;letter-spacing:-.045em}.login-copy>p{max-width:570px;color:var(--ink-soft);font-size:1.02rem;line-height:1.8}.login-feature-list{margin:30px 0 0;padding:0;display:grid;gap:13px;list-style:none;color:#334155;font-size:.9rem}.login-feature-list li{display:flex;align-items:center;gap:10px}.login-feature-list li:before{content:"✓";width:22px;height:22px;display:grid;place-content:center;border-radius:50%;color:var(--success);background:var(--success-soft);font-size:.72rem;font-weight:800}.login-panel{min-width:0;min-height:100vh;padding:36px clamp(24px,6vw,80px);display:grid;place-items:center}.login-card{width:100%;max-width:440px;min-width:0;padding:34px;border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--surface);box-shadow:var(--shadow)}.login-card-heading{margin-bottom:24px}.login-card-heading h2{margin-bottom:9px;font-size:1.65rem}.login-card-heading p{margin-bottom:0;color:var(--ink-soft);font-size:.86rem;line-height:1.6}.auth-tabs{margin-bottom:22px;padding:4px;display:grid;grid-template-columns:1fr 1fr;border-radius:9px;background:#f1f5f9}.auth-tabs button{min-height:36px;border:0;border-radius:7px;color:var(--ink-soft);background:transparent;cursor:pointer}.auth-tabs button.active{color:var(--ink);background:var(--surface);box-shadow:var(--shadow-sm);font-weight:600}.login-card form{display:grid;gap:16px}.code-row{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:10px}.mode-switch{width:100%;margin-top:16px;text-align:center}.demo-hint{margin-top:24px;padding-top:20px;border-top:1px solid var(--line)}.demo-hint>strong{display:block;margin-bottom:10px;color:#475569;font-size:.78rem}.demo-account-row{display:grid;gap:7px}.demo-account-row button{min-width:0;min-height:39px;padding:8px 10px;display:flex;align-items:center;justify-content:space-between;gap:8px;border:1px solid var(--line);border-radius:8px;color:#334155;background:var(--surface-soft);cursor:pointer}.demo-account-row button:hover{border-color:#93c5fd;background:var(--primary-soft)}.demo-account-row code{color:var(--ink-soft);font-size:.75rem}.portal-links{margin-top:18px;display:flex;justify-content:center;gap:18px;color:var(--primary);font-size:.78rem}.portal-links a:hover{text-decoration:underline}.center-page{min-height:70vh;display:grid;place-content:center}.center-page .empty-state{min-width:min(500px,calc(100vw - 36px))}.brush-number{display:block;margin-bottom:8px;color:var(--primary);font-size:4.5rem;font-weight:750;letter-spacing:-.06em}@media(max-width:1040px){.topbar{grid-template-columns:auto 1fr auto;gap:14px}.main-nav{justify-self:center;gap:0}.main-nav a{padding:0 9px}.brand small{display:none}.stat-grid,.paper-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.live-layout,.teacher-live-layout{grid-template-columns:1fr}.class-aside{min-height:auto}.login-page{grid-template-columns:minmax(0,.85fr) minmax(420px,1fr)}.login-copy h1{font-size:clamp(2rem,4vw,3rem)}}@media(max-width:760px){.topbar{min-height:auto;padding:13px 16px 0;grid-template-columns:1fr auto;gap:10px}.topbar .brand-logo{width:38px;height:38px}.topbar .brand strong{font-size:1rem}.main-nav{width:calc(100% + 32px);margin-left:-16px;padding:0 8px;grid-column:1 / -1;grid-row:2;justify-self:stretch;overflow-x:auto;border-top:1px solid var(--line)}.main-nav a{min-height:48px;flex:1 0 auto}.account-block{gap:8px}.account-block span small{display:none}.page-wrap{padding-top:24px;padding-bottom:52px}.hero{min-height:190px;padding:28px 24px}.hero:after{width:180px;height:180px}.stat-grid,.paper-grid,.course-grid,.two-column-admin{grid-template-columns:1fr}.stat-card{min-height:112px}.lesson-card{align-items:flex-start;flex-wrap:wrap}.lesson-card .grow{min-width:calc(100% - 80px)}.ledger-summary{align-items:flex-start;flex-direction:column;gap:22px}.ledger-summary dl{width:100%}.ledger-summary dl div{min-width:0;padding:0 12px;flex:1}.ledger-summary dl div:first-child{border-left:0}.assignment-card>header{flex-direction:column}.lesson-row{padding:14px 0;grid-template-columns:1fr auto}.lesson-row>span{grid-column:1 / -1}.review-form{align-items:stretch;flex-direction:column}.review-form>label:first-child{width:100%}.form-grid{grid-template-columns:1fr}.span-2{grid-column:auto}.page-heading{align-items:flex-start;flex-direction:column}.section-heading{align-items:flex-start}.live-header{align-items:flex-start;flex-direction:column;gap:12px}.live-controls{flex-wrap:wrap}.video-stage{min-height:52vh}.login-page{display:block}.login-intro{min-height:auto;padding:24px 20px 28px;border-right:0;border-bottom:1px solid var(--line)}.login-copy{margin-top:50px}.login-copy h1{font-size:2.1rem}.login-copy>p,.login-feature-list{display:none}.login-panel{width:100%;min-height:auto;padding:24px 16px 40px}.login-card{padding:24px;box-shadow:var(--shadow-sm)}.portal-links{align-items:center;flex-direction:column;gap:9px}}@media(max-width:420px){.account-block span{display:none}.section-heading{flex-direction:column}.course-card{padding:24px}.login-card{padding:21px}}