:root{--font-display:"Sora",sans-serif;--font-body:"Plus Jakarta Sans",sans-serif;--font-serif:"Fraunces",Georgia,serif;--paper:#FFFFFF;--cream:#FBF8F4;--cream-2:#F5F0EA;--cream-3:#EDE6DC;--ink:#1A1207;--ink-2:#4A3F2E;--ink-3:#7D7264;--ink-4:#A89B86;--accent:#E8581C;--accent-soft:#FBE6D9;--accent-quiet:#F0C9B0;--teal-deep:#0F2A2E;--teal-soft:#E2EDEC;--gold-soft:#F8ECD2;--green-soft:#DDEFE3;--red-soft:#F6DCDC;--line:rgba(26,18,7,0.08);--line-mid:rgba(26,18,7,0.14);--line-strong:rgba(26,18,7,0.22);--shadow-edge:inset 0 -1px 0 rgba(26,18,7,0.04);--shadow-atlas-1:0 1px 3px rgba(26,18,7,0.04),0 0 0 1px rgba(26,18,7,0.04);--shadow-atlas-2:0 4px 14px rgba(26,18,7,0.06),0 0 0 1px rgba(26,18,7,0.05);--radius-atlas:14px;--radius-atlas-lg:22px;--radius-pill:999px;--ease-atlas:cubic-bezier(.22,1,.36,1);--orange:#E8581C;--orange-rgb:232 88 28;--orange-light:#FF7A3D;--accent-warm-rgb:232 88 28;--accent-warm:#E8581C;--accent-warm-strong:#C2440F;--gold:#F5A623;--gold-rgb:245 166 35;--teal:#0891B2;--green:#16A34A;--green-rgb:22 163 74;--purple:#7C3AED;--purple-rgb:124 58 237;--purple-light:#9333EA;--pink:#DB2777;--red:#DC2626;--marigold-rgb:245 166 35;--success:var(--green);--warning:var(--gold);--info:var(--teal);--danger:var(--red);--primary:var(--orange);--primary-light:var(--orange-light);--primary-hover:var(--accent-warm-strong);--border-base:var(--border);--surface-sunken:var(--surface-2);--mastery-low:var(--red);--mastery-mid:var(--gold);--mastery-high:var(--green);--mastery-level-0:#D1D5DB;--mastery-level-1:var(--gold);--mastery-level-2:#F97316;--mastery-level-3:var(--green);--mastery-level-4:var(--green-strong);--success-strong:#166534;--warning-strong:#B45309;--info-strong:#0E7490;--danger-strong:#B91C1C;--green-strong:#15803D;--secondary:var(--purple);--xp-color:var(--gold);--streak-color:var(--orange);--level-up:var(--purple);--danger-light:#FCE4E4;--subject-math:#5B4FCF;--subject-science:var(--info-strong);--subject-physics:#1D4ED8;--subject-chemistry:var(--danger-strong);--subject-biology:var(--green-strong);--subject-english:#BE185D;--subject-hindi:var(--accent-warm-strong);--subject-social:var(--warning-strong);--bg:#FBF8F4;--bg-rgb:251,248,244;--surface-1:#FFFFFF;--surface-2:#F5F0EA;--surface-3:#EDE6DC;--border:rgba(0,0,0,0.08);--border-mid:rgba(0,0,0,0.12);--border-strong:rgba(0,0,0,0.18);--border-control:var(--ink-3);--text-1:#1A1207;--text-2:#4A3F2E;--text-3:#6B6053;--shadow-sm:0 1px 4px rgba(0,0,0,0.04);--shadow-md:0 2px 12px rgba(0,0,0,0.06);--shadow-lg:0 8px 24px rgba(0,0,0,0.08);--shadow-glow:0 0 24px rgba(232,88,28,0.15);--scrim:rgba(26,18,7,0.45);--radius-sm:0.125rem;--radius-md:0.375rem;--radius-lg:0.5rem;--radius-xl:0.75rem;--radius-2xl:1rem;--btn-primary-from:#CB4710;--btn-primary-to:#C2440F;--sidebar-width:300px;--nav-rail-width:96px;--nav-rail-width-effective:calc(var(--nav-rail-width) + var(--safe-left));--header-height:60px;--content-max:720px;--content-max-wide:1080px;--focus-ring-color:var(--orange);--focus-ring-width:2px;--focus-ring-offset:2px;--focus-ring-radius:4px;--focus-ring:var(--focus-ring-width) solid var(--focus-ring-color);--duration-instant:80ms;--duration-fast:140ms;--duration-base:200ms;--duration-slow:320ms;--duration-slower:480ms;--ease-standard:cubic-bezier(.2,0,0,1);--ease-out:cubic-bezier(0,0,.2,1);--ease-in:cubic-bezier(.4,0,1,1);--ease-emphasized:var(--ease-atlas);--z-base:0;--z-raised:1;--z-sticky:10;--z-drawer:40;--z-nav:50;--z-modal:60;--z-toast:70;--z-tooltip:80;--z-overlay:90;--z-skip:9999;--surface-inverse:#241A2E;--on-surface-inverse:#F4ECDB;--on-surface-inverse-muted:#C9BCA6;--on-accent:#FFFFFF;--surface-accent:linear-gradient(135deg,var(--btn-primary-from),var(--btn-primary-to));--on-surface-accent:#FFFFFF;--text-2xs:0.75rem;--text-xs:clamp(0.75rem,0.71rem + 0.18vw,0.8125rem);--text-sm:clamp(0.8125rem,0.77rem + 0.22vw,0.875rem);--text-base:clamp(0.9375rem,0.89rem + 0.24vw,1rem);--text-md:clamp(1rem,0.94rem + 0.28vw,1.125rem);--text-lg:clamp(1.125rem,1.05rem + 0.37vw,1.25rem);--text-xl:clamp(1.25rem,1.13rem + 0.6vw,1.5rem);--text-2xl:clamp(1.5rem,1.31rem + 0.93vw,1.875rem);--text-3xl:clamp(1.75rem,1.46rem + 1.39vw,2.25rem);--text-4xl:clamp(2rem,1.6rem + 1.85vw,2.75rem);--text-5xl:clamp(2.5rem,1.93rem + 2.5vw,3.5rem);--text-display:clamp(2.75rem,2.07rem + 2.78vw,3.75rem);--space-fluid-1:clamp(0.25rem,0.22rem + 0.09vw,0.3125rem);--space-fluid-2:clamp(0.375rem,0.34rem + 0.18vw,0.5rem);--space-fluid-3:clamp(0.5rem,0.45rem + 0.22vw,0.625rem);--space-fluid-4:clamp(0.75rem,0.68rem + 0.37vw,1rem);--space-fluid-5:clamp(1rem,0.91rem + 0.46vw,1.25rem);--space-fluid-6:clamp(1.25rem,1.13rem + 0.6vw,1.5rem);--space-fluid-7:clamp(1.5rem,1.31rem + 0.93vw,2rem);--space-fluid-8:clamp(2rem,1.74rem + 1.3vw,2.75rem);--space-fluid-9:clamp(2.5rem,2.13rem + 1.85vw,3.5rem);--space-fluid-10:clamp(3rem,2.5rem + 2.5vw,4.5rem);--space-fluid-11:clamp(4rem,3.32rem + 3.33vw,6rem);--space-fluid-12:clamp(5rem,4rem + 5vw,8rem);--space-1:0.25rem;--space-2:0.5rem;--space-3:0.75rem;--space-4:1rem;--space-6:1.5rem;--space-8:2rem;--space-12:3rem;--space-16:4rem;--tap-min:44px;--tap-comfort:48px;--tap-large:56px;--tap-hero:72px;--safe-top:env(safe-area-inset-top,0px);--safe-bottom:env(safe-area-inset-bottom,0px);--safe-left:env(safe-area-inset-left,0px);--safe-right:env(safe-area-inset-right,0px);--reach-bottom:33vh;--reach-comfort:50vh;--reach-stretch:75vh;--reading-max:70ch;--layout-max-content:min(1240px,100% - 2 * var(--space-fluid-4));--layout-max-rail:220px;--layout-max-aside:320px;--shell-header-h:56px;--shell-header-h-compact:44px;--shell-nav-h:60px;--shell-nav-h-notched:calc(60px + var(--safe-bottom))}@media (prefers-reduced-motion:reduce){:root{--duration-instant:0.01ms;--duration-fast:0.01ms;--duration-base:0.01ms;--duration-slow:0.01ms;--duration-slower:0.01ms}}:root{--st-page:#F7F4EF;--st-card:#FFFFFF;--st-sunken:#F1ECE5;--st-line:rgba(26,18,7,0.09);--st-line-strong:rgba(26,18,7,0.16);--st-ink:var(--text-1);--st-ink-2:var(--text-2);--st-ink-3:var(--text-3);--st-action:#C2440F;--st-action-hover:#A93A0C;--st-action-ink:#B23E0C;--st-action-tint:#FCEDE4;--st-learn:#B23E0C;--st-learn-tint:#FCEDE4;--st-review:#0E6A80;--st-review-tint:#E2F1F4;--st-help:#5B32B4;--st-help-tint:#EFEAFB;--st-good:#166534;--st-good-tint:#E3F2E7;--st-attn:#9A4A06;--st-attn-tint:#FBEFD9;--st-wrong:#B91C1C;--st-wrong-tint:#FBE7E5;--st-radius:18px;--st-radius-md:14px;--st-radius-sm:10px;--st-shadow:0 1px 2px rgba(26,18,7,0.04),0 0 0 1px var(--st-line);--st-shadow-raised:0 10px 28px -12px rgba(26,18,7,0.22),0 0 0 1px var(--st-line);--st-display:clamp(1.625rem,1.3rem + 1.4vw,2.125rem);--st-h1:clamp(1.375rem,1.2rem + 0.8vw,1.75rem);--st-h2:clamp(1.125rem,1.05rem + 0.3vw,1.25rem);--st-body:1rem;--st-small:0.875rem;--st-label:0.75rem;--st-gap:16px;--st-ease:cubic-bezier(.22,1,.36,1)}.bottom-nav-mobile__icon,.nav-rail-tablet__icon{display:inline-flex;align-items:center;justify-content:center;width:56px;height:30px;border-radius:999px;font-size:22px;transition:background-color .18s var(--st-ease)}.bottom-nav-mobile__slot[data-active=true] .bottom-nav-mobile__icon,.nav-rail-tablet__slot[data-active=true] .nav-rail-tablet__icon{background:var(--st-action-tint);color:var(--st-action-ink)}.bottom-nav-mobile__slot[data-active=true] .bottom-nav-mobile__icon svg,.nav-rail-tablet__slot[data-active=true] .nav-rail-tablet__icon svg{stroke-width:2.1px}.bottom-nav-mobile__slot:after{display:none}.bottom-nav-mobile{box-shadow:0 -1px 0 var(--st-line);border-top:0}.bottom-nav-mobile__badge{top:-4px;right:6px;font-size:10px;background:var(--st-attn)}@media (prefers-reduced-motion:reduce){.bottom-nav-mobile__icon,.nav-rail-tablet__icon{transition:none}}.st-display,.st-h1,.st-h2{font-family:var(--font-display);color:var(--st-ink);letter-spacing:-.015em;text-wrap:balance;margin:0}.st-display{font-size:var(--st-display);line-height:1.15;font-weight:700}.st-h1{font-size:var(--st-h1);line-height:1.2;font-weight:700}.st-h2{font-size:var(--st-h2);line-height:1.3;font-weight:650}.st-lead{font-size:var(--st-body);line-height:1.55;color:var(--st-ink-2);margin:0;text-wrap:pretty}.st-small{font-size:var(--st-small);line-height:1.5}.st-eyebrow,.st-small{color:var(--st-ink-3);margin:0}.st-eyebrow{font-size:var(--st-label);line-height:1.2;font-weight:700;letter-spacing:.06em;text-transform:uppercase}.st-card{background:var(--st-card);border-radius:var(--st-radius);box-shadow:var(--st-shadow);padding:20px}.st-card--raised{box-shadow:var(--st-shadow-raised)}.st-card--sunken{background:var(--st-sunken);box-shadow:none}.st-stack{gap:var(--st-gap)}.st-stack,.st-stack-sm{display:flex;flex-direction:column}.st-stack-sm{gap:8px}.st-divider{height:1px;background:var(--st-line);border:0;margin:0}.st-btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:52px;padding:0 22px;border-radius:14px;border:0;background:var(--st-action);color:#fff;font-family:var(--font-body);font-size:1rem;font-weight:700;line-height:1.2;text-align:center;text-decoration:none;cursor:pointer;-webkit-tap-highlight-color:transparent;transition:background-color .15s var(--st-ease),transform .12s var(--st-ease)}.st-btn:hover{background:var(--st-action-hover)}.st-btn:active{transform:scale(.985)}.st-btn-quiet:focus-visible,.st-btn:focus-visible,.st-chip:focus-visible,.st-row:focus-visible{outline:3px solid var(--st-action-ink);outline-offset:2px}.st-btn:disabled,.st-btn[aria-disabled=true]{opacity:.55;cursor:not-allowed;transform:none}.st-btn--block{width:100%}.st-btn-quiet{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:0 18px;border-radius:14px;background:var(--st-card);color:var(--st-ink);box-shadow:inset 0 0 0 1.5px var(--st-line-strong);border:0;font-size:1rem;font-weight:650;text-decoration:none;cursor:pointer;-webkit-tap-highlight-color:transparent}.st-btn-quiet:hover{background:var(--st-sunken)}.st-link{color:var(--st-action-ink);font-weight:650;text-decoration:underline;text-underline-offset:3px;text-decoration-thickness:1.5px}.st-row{display:flex;align-items:center;gap:14px;min-height:64px;padding:12px 14px;border-radius:var(--st-radius-md);background:var(--st-card);box-shadow:var(--st-shadow);color:var(--st-ink);text-decoration:none;text-align:left;width:100%;border:0;cursor:pointer;-webkit-tap-highlight-color:transparent;transition:box-shadow .15s var(--st-ease)}.st-row:hover{box-shadow:var(--st-shadow-raised)}.st-row__text{display:flex;flex-direction:column;gap:2px;min-width:0;flex:1}.st-row__title{font-size:var(--st-body);font-weight:650;line-height:1.3;color:var(--st-ink)}.st-row__meta{font-size:var(--st-small);line-height:1.4;color:var(--st-ink-3)}.st-row__chev{color:var(--st-ink-3);flex-shrink:0}.st-tile{display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;width:44px;height:44px;border-radius:12px;background:var(--st-sunken);color:var(--st-ink-2)}.st-tile--lg{width:52px;height:52px;border-radius:14px}.st-tone-learn{--st-tone:var(--st-learn);--st-tone-tint:var(--st-learn-tint)}.st-tone-review{--st-tone:var(--st-review);--st-tone-tint:var(--st-review-tint)}.st-tone-help{--st-tone:var(--st-help);--st-tone-tint:var(--st-help-tint)}.st-tone-good{--st-tone:var(--st-good);--st-tone-tint:var(--st-good-tint)}.st-tone-attn{--st-tone:var(--st-attn);--st-tone-tint:var(--st-attn-tint)}.st-tone-wrong{--st-tone:var(--st-wrong);--st-tone-tint:var(--st-wrong-tint)}.st-tile[class*=st-tone-]{background:var(--st-tone-tint);color:var(--st-tone)}.st-chip{display:inline-flex;align-items:center;gap:6px;min-height:28px;padding:2px 10px;border-radius:999px;font-size:var(--st-small);font-weight:650;line-height:1.2;background:var(--st-sunken);color:var(--st-ink-2)}.st-chip[class*=st-tone-]{background:var(--st-tone-tint);color:var(--st-tone)}.st-meter{position:relative;height:8px;border-radius:999px;background:var(--st-sunken);overflow:hidden}.st-meter>span{position:absolute;inset:0 auto 0 0;border-radius:inherit;background:var(--st-tone,var(--st-action))}.st-callout{display:flex;gap:12px;align-items:flex-start;padding:14px 16px;border-radius:var(--st-radius-md);background:var(--st-tone-tint,var(--st-sunken));color:var(--st-ink)}.st-callout__icon{color:var(--st-tone,var(--st-ink-2));flex-shrink:0;margin-top:1px}.st-callout__title{font-weight:700;color:var(--st-tone,var(--st-ink));margin:0 0 2px;font-size:var(--st-body)}.st-split{display:grid;gap:24px;grid-template-columns:minmax(0,1fr)}@media (min-width:1024px){.st-split{grid-template-columns:minmax(0,1.55fr) minmax(300px,1fr);align-items:start}.st-split>.st-split__aside{position:sticky;top:24px}}@media (prefers-reduced-motion:reduce){.st-btn,.st-btn-quiet,.st-row{transition:none}.st-btn:active{transform:none}}.st-reader{max-width:44rem;margin:0 auto;padding:8px 16px 120px;display:flex;flex-direction:column;gap:24px}@media (min-width:768px){.st-reader{padding:24px 24px 64px}}.st-reader__progress{position:sticky;top:0;z-index:5;height:3px;margin:0 -16px;background:transparent}.st-reader__progress>span{display:block;height:100%;background:var(--st-action);border-radius:0 3px 3px 0;transition:width .2s linear}.st-reader__top{display:flex;align-items:center}.st-reader__back{display:inline-flex;align-items:center;gap:6px;min-height:44px;padding:0 8px 0 0;border:0;background:none;color:var(--st-ink-2);font-weight:650;font-size:var(--st-body);cursor:pointer}.st-reader__back:focus-visible{outline:3px solid var(--st-action-ink);outline-offset:2px;border-radius:8px}.st-reader__body{display:flex;flex-direction:column;gap:28px;font-size:1.0625rem;line-height:1.7;color:var(--st-ink)}.st-reader__body p{max-width:65ch}@media (prefers-reduced-motion:reduce){.st-reader__progress>span{transition:none}}