:root{--kl-font:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;--kl-font-display:"Fraunces",Georgia,"Times New Roman",serif;--kl-font-sans:var(--kl-font);--kl-font-mono:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;--kl-text-xs:0.75rem;--kl-text-sm:0.875rem;--kl-text-base:1rem;--kl-text-md:0.9375rem;--kl-text-lg:1.125rem;--kl-text-xl:1.25rem;--kl-text-2xl:1.5rem;--kl-text-3xl:1.875rem;--kl-text-4xl:clamp(2.25rem,5vw,3rem);--kl-text-display:clamp(2.25rem,5vw,3rem);--kl-text-hero-lead:clamp(0.875rem,1.4vw,1rem);--kl-text-7xl:4.5rem;--kl-text-8xl:6rem;--kl-leading-tight:1.15;--kl-leading-snug:1.375;--kl-leading-normal:1.5;--kl-leading-relaxed:1.625;--kl-leading-editorial:1.45;--kl-weight-regular:400;--kl-weight-normal:var(--kl-weight-regular);--kl-weight-medium:500;--kl-weight-semibold:600;--kl-weight-bold:700;--kl-weight-extrabold:800;--kl-tracking-tight:-0.02em;--kl-tracking-normal:0;--kl-tracking-wide:0.04em;--kl-tracking-wider:0.06em;--kl-tracking-widest:0.1em;--kl-ink-900:#1a1a1f;--kl-ink-700:#3f3f46;--kl-ink-500:#6b7280;--kl-ink-400:var(--kl-ink-500);--kl-ink-300:#a1a1aa;--kl-ink-100:#e7e7e4;--kl-ink-inverse:#fafaf9;--kl-surface-base:#fafaf9;--kl-surface-page:var(--kl-surface-base);--kl-page-bg:var(--kl-surface-page);--kl-surface-0:#ffffff;--kl-surface-1:#f3f3f1;--kl-surface-subtle:var(--kl-surface-1);--kl-surface-2:#f8f8f6;--kl-surface-3:#e7e7e4;--kl-surface-inverse:#1a1a1f;--kl-primary:#2a5bd7;--kl-primary-hover:#214bb8;--kl-primary-pressed:#1a3d96;--kl-primary-subtle:#f5f7ff;--kl-brand-soft:var(--kl-primary-subtle);--kl-primary-disabled:#c5d2f5;--kl-accent:#e6a100;--kl-accent-hover:#c98900;--kl-accent-pressed:#a67000;--kl-accent-subtle:#fff9eb;--kl-mint:#16803c;--kl-mint-hover:#136b32;--kl-mint-pressed:#0f5628;--kl-mint-subtle:#ecfdf3;--kl-violet:var(--kl-primary);--kl-violet-hover:var(--kl-primary-hover);--kl-violet-pressed:var(--kl-primary-hover);--kl-violet-subtle:var(--kl-primary-subtle);--kl-success:#16803c;--kl-success-hover:#136b32;--kl-success-subtle:#ecfdf3;--kl-success-text:#16803c;--kl-warning:#9a6700;--kl-warning-hover:#7a5200;--kl-warning-subtle:#fff8e1;--kl-warning-text:#9a6700;--kl-error:#c9343a;--kl-error-hover:#a82a30;--kl-error-subtle:#fff1f2;--kl-error-text:#c9343a;--kl-info:#2a5bd7;--kl-info-hover:#214bb8;--kl-info-subtle:#f5f7ff;--kl-info-text:#214bb8;--kl-saved:#f43f5e;--kl-saved-soft:#ffe4e6;--kl-clipart-preview-bg:#f3f6fd;--kl-account-banner-bg:#ebf0ff;--kl-premium-bg:#fff9eb;--kl-premium-text:#7a5200;--kl-premium-border:#f4e2b8;--kl-premium-solid:#e6a100;--kl-footer-bg:#1a1a1f;--kl-footer-border:#2b2b31;--kl-footer-heading:#d7d7da;--kl-footer-link:#b1b1b6;--kl-footer-link-hover:#ffffff;--kl-footer-meta:#85858d;--kl-footer-icon-bg:#24242a;--kl-footer-icon:#b7b7bc;--kl-border:#e7e7e4;--kl-border-strong:#d4d4d0;--kl-border-subtle:#ececea;--kl-focus-ring:rgba(42,91,215,0.25);--kl-overlay-scrim:rgba(26,26,31,0.4);--kl-disabled-bg:#f3f3f1;--kl-disabled-text:rgba(107,114,128,0.55);--kl-link-color:var(--kl-primary);--kl-link-color-hover:var(--kl-primary-hover);--kl-action-primary-bg:var(--kl-primary);--kl-action-primary-bg-hover:var(--kl-primary-hover);--kl-action-primary-bg-pressed:var(--kl-primary-pressed);--kl-action-primary-bg-disabled:var(--kl-primary-disabled);--kl-action-primary-fg:#ffffff;--kl-action-primary-fg-disabled:rgba(255,255,255,0.6);--kl-action-secondary-bg:var(--kl-surface-0);--kl-action-secondary-bg-hover:var(--kl-surface-1);--kl-action-secondary-fg:var(--kl-ink-900);--kl-action-secondary-fg-active:var(--kl-ink-900);--kl-action-secondary-border:var(--kl-border-subtle);--kl-action-secondary-selected-border:var(--kl-primary);--kl-action-secondary-selected-fg:var(--kl-primary);--kl-action-secondary-selected-bg:var(--kl-primary-subtle);--kl-action-secondary-on-gradient-bg:var(--kl-surface-0);--kl-action-secondary-on-gradient-bg-hover:var(--kl-surface-1);--kl-action-ghost-bg:transparent;--kl-action-ghost-bg-hover:var(--kl-surface-1);--kl-action-ghost-bg-active:var(--kl-surface-3);--kl-action-ghost-fg:var(--kl-ink-500);--kl-action-ghost-fg-hover:var(--kl-ink-900);--kl-action-soft-bg:var(--kl-primary-subtle);--kl-action-soft-bg-hover:color-mix(in srgb,var(--kl-primary) 12%,var(--kl-primary-subtle));--kl-action-soft-bg-active:color-mix(in srgb,var(--kl-primary) 18%,var(--kl-primary-subtle));--kl-action-soft-fg:var(--kl-primary);--kl-action-danger-bg:var(--kl-error);--kl-action-danger-bg-hover:var(--kl-error-hover);--kl-action-danger-fg:#ffffff;--kl-action-danger-bg-disabled:color-mix(in srgb,var(--kl-error) 28%,var(--kl-surface-1));--kl-action-danger-fg-disabled:rgba(255,255,255,0.6);--kl-action-download-bg:var(--kl-mint);--kl-action-download-bg-hover:var(--kl-mint-hover);--kl-action-download-bg-pressed:var(--kl-mint-pressed);--kl-action-download-fg:#ffffff;--kl-action-download-bg-disabled:var(--kl-mint-subtle);--kl-action-download-fg-disabled:var(--kl-mint);--kl-control-selected-bg:var(--kl-action-primary-bg);--kl-control-selected-fg:var(--kl-action-primary-fg);--kl-control-selected-border:var(--kl-action-primary-bg);--kl-control-accent-fg:var(--kl-link-color);--kl-nav-bar-bg:color-mix(in srgb,var(--kl-surface-0) 90%,transparent);--kl-nav-bar-border:var(--kl-border-subtle);--kl-nav-item-fg:var(--kl-ink-500);--kl-nav-item-fg-hover:var(--kl-ink-900);--kl-nav-item-hover-bg:var(--kl-surface-1);--kl-nav-item-active-bg:var(--kl-primary-subtle);--kl-nav-item-active-fg:var(--kl-primary);--kl-nav-item-active-bg-sidebar:var(--kl-primary-subtle);--kl-nav-item-active-fg-sidebar:var(--kl-primary);--kl-menu-bg:var(--kl-surface-0);--kl-menu-border:var(--kl-border-subtle);--kl-menu-shadow:var(--kl-shadow-floating);--kl-menu-item-fg:var(--kl-ink-500);--kl-menu-item-hover-bg:var(--kl-surface-1);--kl-menu-item-hover-fg:var(--kl-ink-900);--kl-menu-trigger-hover-bg:var(--kl-surface-1);--kl-menu-trigger-hover-border:color-mix(in srgb,var(--kl-ink-500) 20%,transparent);--kl-menu-trigger-hover-fg:var(--kl-ink-900);--kl-menu-trigger-open-bg:var(--kl-surface-1);--kl-menu-trigger-open-border:var(--kl-border-subtle);--kl-menu-trigger-open-fg:var(--kl-ink-900);--kl-avatar-bg:var(--kl-action-primary-bg);--kl-avatar-fg:var(--kl-action-primary-fg);--kl-badge-bg:var(--kl-action-primary-bg);--kl-badge-fg:var(--kl-action-primary-fg);--kl-brand-mark-gradient-start:var(--kl-primary);--kl-brand-mark-gradient-end:var(--kl-primary);--kl-field-focus-border:var(--kl-primary);--kl-field-focus-shadow:0 0 0 2px var(--kl-focus-ring);--kl-focus-color:var(--kl-primary);--kl-danger-surface-border:color-mix(in srgb,var(--kl-error) 20%,var(--kl-border));--kl-danger-surface-bg:color-mix(in srgb,var(--kl-error) 6%,var(--kl-surface-0));--kl-panel-bg:var(--kl-surface-0);--kl-panel-border:var(--kl-border-subtle);--kl-type-worksheet:var(--kl-primary);--kl-type-story:var(--kl-primary);--kl-type-guide:var(--kl-primary);--kl-type-clipart:var(--kl-primary);--kl-type-collection:var(--kl-primary);--kl-type-worksheet-subtle:var(--kl-primary-subtle);--kl-type-story-subtle:var(--kl-primary-subtle);--kl-type-guide-subtle:var(--kl-primary-subtle);--kl-type-clipart-subtle:var(--kl-primary-subtle);--kl-type-collection-subtle:var(--kl-primary-subtle);--kl-difficulty-easy:#16803c;--kl-difficulty-medium:#9a6700;--kl-difficulty-hard:#c9343a;--kl-hero-home:var(--kl-primary-subtle);--kl-hero-worksheet:var(--kl-primary-subtle);--kl-hero-story:var(--kl-primary-subtle);--kl-hero-guide:var(--kl-primary-subtle);--kl-hero-clipart:var(--kl-primary-subtle);--kl-hero-account:#fafaf9;--kl-space-0:0;--kl-space-1:0.25rem;--kl-space-1-5:0.375rem;--kl-space-2:0.5rem;--kl-space-2-5:0.625rem;--kl-space-3:0.75rem;--kl-space-3-5:0.875rem;--kl-space-4:1rem;--kl-space-5:1.25rem;--kl-space-6:1.5rem;--kl-space-7:1.75rem;--kl-space-8:2rem;--kl-space-10:2.5rem;--kl-space-12:3rem;--kl-space-14:3.5rem;--kl-space-16:4rem;--kl-space-20:5rem;--kl-section-gap:var(--kl-space-12);--kl-section-gap-sm:var(--kl-space-10);--kl-section-gap-lg:var(--kl-space-16);--kl-section-gap-breathe:var(--kl-space-20);--kl-stack-gap:var(--kl-space-4);--kl-stack-gap-sm:var(--kl-space-2);--kl-stack-gap-lg:var(--kl-space-6);--kl-card-gap:var(--kl-space-4);--kl-grid-gap:var(--kl-space-6);--kl-grid-gap-sm:var(--kl-space-4);--kl-grid-gap-lg:var(--kl-space-6);--kl-sidebar-gap:var(--kl-space-6);--kl-container-gap:var(--kl-space-8);--kl-spacing-hero:3.5rem;--kl-spacing-section:3rem;--kl-spacing-card:1.5rem;--kl-search-hit-thumb-size:3rem;--kl-grid-card-min:11.5rem;--kl-grid-card-min-compact:8.75rem;--kl-hub-grid-min:15rem;--kl-letter-grid-min:3.5rem;--kl-measure-narrow:36rem;--kl-measure-comfort:42rem;--kl-measure-wide:48rem;--kl-surface-xs:22rem;--kl-surface-sm:28rem;--kl-surface-md:42rem;--kl-surface-lg:56rem;--kl-form-auth-login:460px;--kl-form-auth-signup:520px;--kl-form-auth-standard:420px;--kl-home-hero-preview-max:23.75rem;--kl-page-max:80rem;--kl-page-max-reading:56rem;--kl-page-max-compact:42rem;--kl-page-max-auth:28rem;--kl-page-gutter:1rem;--kl-container:var(--kl-page-max);--kl-container-wide:var(--kl-page-max);--kl-container-narrow:var(--kl-page-max-compact);--kl-container-compact:var(--kl-page-max-compact);--kl-container-reading:var(--kl-page-max-reading);--kl-container-auth:var(--kl-page-max-auth);--kl-sidebar-width:320px;--kl-sidebar-width-lg:360px;--kl-account-sidebar-w:16rem;--kl-header-h:4rem;--kl-header-max:var(--kl-page-max);--kl-bp-sm:480px;--kl-bp-md:640px;--kl-bp-lg:768px;--kl-bp-xl:1024px;--kl-bp-2xl:1280px;--kl-radius-xs:0.125rem;--kl-radius-sm:0.25rem;--kl-radius-md:0.375rem;--kl-radius-lg:0.5rem;--kl-radius-xl:0.75rem;--kl-radius-2xl:1rem;--kl-radius-3xl:1.5rem;--kl-radius-pill:9999px;--kl-shadow-none:none;--kl-shadow-xs:0 1px 2px rgba(26,26,31,0.04);--kl-shadow-sm:0 1px 2px rgba(26,26,31,0.04);--kl-shadow:var(--kl-shadow-xs);--kl-shadow-surface:0 1px 2px rgba(26,26,31,0.04);--kl-shadow-md:0 4px 16px -2px rgba(26,26,31,0.06),0 2px 6px -1px rgba(26,26,31,0.02);--kl-shadow-hover:0 4px 16px -2px rgba(26,26,31,0.06),0 2px 6px -1px rgba(26,26,31,0.02);--kl-shadow-lg:0 12px 28px -4px rgba(26,26,31,0.08),0 4px 12px -2px rgba(26,26,31,0.04);--kl-shadow-xl:var(--kl-shadow-lg);--kl-shadow-2xl:var(--kl-shadow-lg);--kl-shadow-floating:0 12px 28px -4px rgba(26,26,31,0.08),0 4px 12px -2px rgba(26,26,31,0.04);--kl-shadow-sticky:0 1px 2px rgba(26,26,31,0.04);--kl-border-width:1px;--kl-border-width-strong:2px;--kl-z-base:1;--kl-z-dropdown:20;--kl-z-sticky:30;--kl-z-header:40;--kl-z-overlay:50;--kl-z-modal:60;--kl-z-toast:70;--kl-duration-fast:150ms;--kl-duration:200ms;--kl-duration-slow:300ms;--kl-ease:cubic-bezier(0.4,0,0.2,1);--kl-ease-out:cubic-bezier(0,0,0.2,1);--kl-card-radius:var(--kl-radius-xl);--kl-card-padding:1rem;--kl-card-padding-sm:1.25rem;--kl-card-media-radius:0;--kl-icon-xs:14px;--kl-icon-button:16px;--kl-icon-sm:20px;--kl-icon-md:24px;--kl-icon-lg:32px;--kl-btn-height-sm:36px;--kl-btn-height-md:40px;--kl-btn-height-lg:44px;--kl-btn-radius:var(--kl-radius-xl);--kl-btn-px-sm:12px;--kl-btn-px-md:16px;--kl-btn-px-lg:24px;--kl-btn-py-sm:6px;--kl-btn-py-md:8px;--kl-btn-py-lg:10px;--kl-input-px:var(--kl-space-3);--kl-input-py:0.625rem;--kl-input-font-size:var(--kl-text-sm);--kl-input-bg:var(--kl-surface-0);--kl-input-focus-ring:2px;--kl-input-radius:var(--kl-radius-xl);--kl-hero-glow-primary:radial-gradient(ellipse 75% 55% at 8% 0%,color-mix(in srgb,var(--kl-primary) 12%,transparent) 0%,transparent 62%);--kl-hero-glow-warm:radial-gradient(ellipse 55% 45% at 92% 8%,color-mix(in srgb,var(--kl-accent) 8%,transparent) 0%,transparent 58%);--kl-hero-bg:var(--kl-hero-glow-primary),var(--kl-hero-glow-warm),var(--kl-surface-base);--kl-thumb-ratio-card:4 / 3;--kl-thumb-position-worksheet:top center;--kl-thumb-ratio-worksheet:4 / 5;--kl-thumb-ratio-clipart:1 / 1;--kl-thumb-ratio-story:16 / 10;--kl-thumb-ratio-guide:16 / 10;--kl-preview-max-h:420px;--kl-touch-min:44px;--kl-focus-outline:2px solid var(--kl-focus-color);--kl-focus-offset:2px;--kl-ink:var(--kl-ink-900);--kl-ink-strong:var(--kl-ink-900);--kl-ink-muted:var(--kl-ink-500);--kl-body-muted:var(--kl-ink-500);--kl-text-muted:var(--kl-ink-500);--kl-ink-subtle:var(--kl-ink-300);--kl-surface:var(--kl-surface-0);--kl-surface-soft:var(--kl-surface-1);--kl-surface-muted:var(--kl-surface-1);--kl-surface-warm:var(--kl-surface-1);--kl-surface-elevated:var(--kl-surface-0);--kl-primary-dark:var(--kl-primary-hover);--kl-primary-soft:var(--kl-primary-subtle);--kl-accent-soft:var(--kl-accent-subtle);--kl-mint-soft:var(--kl-mint-subtle);--kl-violet-soft:var(--kl-violet-subtle);--kl-radius:var(--kl-radius-lg)}@media (min-width:640px){:root{--kl-page-gutter:1.5rem}}@media (min-width:1024px){:root{--kl-page-gutter:2rem}}@media (prefers-reduced-motion:reduce){:root{--kl-duration-fast:0.01ms;--kl-duration:0.01ms;--kl-duration-slow:0.01ms}}.kl-type-display{font-family:var(--kl-font-display);font-size:var(--kl-text-display);font-weight:var(--kl-weight-bold);letter-spacing:var(--kl-tracking-tight);line-height:var(--kl-leading-tight);color:var(--kl-ink-900)}.kl-type-h1{font-family:var(--kl-font-display);font-size:var(--kl-text-4xl);line-height:var(--kl-leading-tight);font-weight:var(--kl-weight-bold);letter-spacing:var(--kl-tracking-tight);color:var(--kl-ink-900)}.kl-type-h2{font-family:var(--kl-font-display);font-size:var(--kl-text-2xl);line-height:var(--kl-leading-tight);font-weight:var(--kl-weight-bold);letter-spacing:var(--kl-tracking-tight);color:var(--kl-ink-900)}.kl-type-h3{font-family:var(--kl-font);font-size:var(--kl-text-sm);line-height:var(--kl-leading-snug);font-weight:var(--kl-weight-bold);color:var(--kl-ink-900)}.kl-type-h4{font-family:var(--kl-font);font-size:var(--kl-text-sm);line-height:var(--kl-leading-snug);font-weight:var(--kl-weight-bold);color:var(--kl-ink-900)}.kl-type-section-label{font-family:var(--kl-font);font-size:var(--kl-text-xs);font-weight:var(--kl-weight-bold);text-transform:uppercase;letter-spacing:var(--kl-tracking-widest);color:var(--kl-primary)}.kl-type-body-lg{font-size:var(--kl-text-sm);line-height:var(--kl-leading-relaxed);font-weight:var(--kl-weight-semibold);color:var(--kl-ink-500)}.kl-type-body{font-size:var(--kl-text-sm);line-height:var(--kl-leading-relaxed);color:var(--kl-ink-500)}.kl-type-body-sm{font-size:var(--kl-text-xs);line-height:var(--kl-leading-normal);color:var(--kl-ink-500)}.kl-type-meta{font-size:var(--kl-text-xs);line-height:var(--kl-leading-normal);font-weight:var(--kl-weight-semibold);color:var(--kl-ink-500)}.kl-type-caption{font-size:var(--kl-text-xs);line-height:var(--kl-leading-normal);color:var(--kl-ink-500)}.kl-type-edu-note{font-family:var(--kl-font);font-size:var(--kl-text-sm);line-height:var(--kl-leading-relaxed);font-weight:var(--kl-weight-semibold);color:var(--kl-ink-500)}.kl-skeleton{background:linear-gradient( 90deg,var(--kl-surface-1) 0%,var(--kl-surface-2) 50%,var(--kl-surface-1) 100% );background-size:200% 100%;animation:kl-skeleton-pulse 1.2s ease-in-out infinite;border-radius:var(--kl-radius-md)}@keyframes kl-skeleton-pulse{0%{background-position:100% 0}100%{background-position:-100% 0}}@media (prefers-reduced-motion:reduce){.kl-skeleton{animation:none}}:focus-visible{outline:2px solid var(--kl-primary) !important;outline-offset:2px !important}