:root{--color-bg: #0f1117;--color-surface: #1a1d27;--color-surface-alt: #232735;--color-border: #2e3347;--color-text: #e4e6ef;--color-text-muted: #8a8fa8;--color-accent: #00c2ff;--color-accent-glow: rgba(0, 194, 255, .25);--color-success: #00e676;--color-warning: #ffab00;--color-error: #ff5252;--font-body: "Inter", system-ui, -apple-system, sans-serif;--font-mono: "JetBrains Mono", "Fira Code", monospace;--text-xs: .75rem;--text-sm: .875rem;--text-base: 1rem;--text-lg: 1.125rem;--text-xl: 1.25rem;--text-2xl: 1.5rem;--text-3xl: 1.875rem;--space-1: .25rem;--space-2: .5rem;--space-3: .75rem;--space-4: 1rem;--space-6: 1.5rem;--space-8: 2rem;--space-12: 3rem;--radius-sm: 4px;--radius-md: 8px;--radius-lg: 12px;--radius-xl: 16px;--shadow-card: 0 2px 8px rgba(0, 0, 0, .35);--shadow-glow: 0 0 12px var(--color-accent-glow);--transition-fast: .12s ease;--transition-base: .2s ease}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{font-size:16px;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}body{font-family:var(--font-body);background:var(--color-bg);color:var(--color-text);line-height:1.6;min-height:100dvh}code,pre{font-family:var(--font-mono)}a{color:var(--color-accent);text-decoration:none}a:hover{text-decoration:underline}button{font-family:inherit;cursor:pointer}@media(max-width:768px){.app-shell{flex-direction:column}.nav-bar{flex-direction:column;gap:var(--space-2);padding:var(--space-2)}.nav-links{gap:var(--space-2)}.main-content{padding:var(--space-3)}.lesson-player__workspace{flex-direction:column}.lesson-player__palette{width:100%;max-height:200px;overflow-y:auto}.lesson-player__canvas{width:100%}.challenge-player__workspace{flex-direction:column}.challenge-player__palette{width:100%;max-height:200px;overflow-y:auto}.circuit-workspace__canvas{max-height:300px}.component-palette__list{display:flex;flex-wrap:wrap;gap:var(--space-1)}.component-palette__item{font-size:.85rem;padding:var(--space-1) var(--space-2)}.challenge-board__grid,.plan-selector__grid{grid-template-columns:1fr}.concept-check__options{flex-direction:column}.concept-check__option{width:100%}.home-stats{flex-wrap:wrap;gap:var(--space-2)}.stat-card{min-width:100px}}@media(min-width:769px)and (max-width:1024px){.lesson-player__workspace{flex-direction:row}.lesson-player__palette{width:250px;flex-shrink:0}.challenge-board__grid,.plan-selector__grid{grid-template-columns:repeat(2,1fr)}}@media(min-width:1025px){.lesson-player__workspace{display:flex;gap:var(--space-4)}.lesson-player__palette{width:280px;flex-shrink:0}.lesson-player__canvas{flex:1}.challenge-board__grid{grid-template-columns:repeat(3,1fr);gap:var(--space-4)}.plan-selector__grid{grid-template-columns:repeat(2,1fr);gap:var(--space-4)}}