:root{--transition-fast:150ms cubic-bezier(0.4,0,0.2,1);--transition-normal:250ms cubic-bezier(0.4,0,0.2,1);--transition-slow:350ms cubic-bezier(0.4,0,0.2,1);--button-height-sm:32px;--button-height-md:40px;--button-height-lg:48px;--input-height-sm:32px;--input-height-md:40px;--input-height-lg:48px;--card-padding-sm:16px;--card-padding-md:24px;--card-padding-lg:32px}*{box-sizing:border-box}html{scroll-behavior:smooth}body{background:var(--bg-primary);color:var(--text-primary);transition:background-color var(--transition-normal),color var(--transition-normal)}:focus{outline:2px solid var(--color-primary-500);outline-offset:2px}:focus:not(:focus-visible){outline:none}::selection{background-color:rgb(168 85 247/.2);color:var(--text-primary)}.gradient-text{background:linear-gradient(135deg,var(--color-primary-500) 0,var(--color-secondary-500) 100%);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}.gradient-bg-primary{background:var(--bg-gradient)}.gradient-bg-brand{background:linear-gradient(135deg,var(--color-primary-500) 0,var(--color-secondary-500) 100%)}.card-elevated{background:var(--bg-primary);border:1px solid var(--border-primary);box-shadow:var(--shadow-md);transition:all var(--transition-normal)}.card-elevated:hover{box-shadow:var(--shadow-lg);transform:translateY(-2px)}.interactive{cursor:pointer;transition:all var(--transition-fast)}.interactive:hover{transform:translateY(-1px)}.interactive:active{transform:translateY(0)}.glass{background:rgba(255,255,255,.1);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.2)}.math-accent{color:#8b5cf6}.ai-accent{color:#ec4899}.progress-accent{color:#10b981}.streak-accent{color:#f59e0b}.animate-fade-in{animation:fadeIn var(--transition-normal) ease-out}.animate-slide-up{animation:slideUp var(--transition-normal) ease-out}.animate-scale-in{animation:scaleIn var(--transition-normal) ease-out}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}@keyframes scaleIn{0%{opacity:0;transform:scale(.95)}to{opacity:1;transform:scale(1)}}@media (max-width:640px){.hide-mobile{display:none}}@media (min-width:641px){.show-mobile{display:none}}@media (max-width:768px){.hide-tablet{display:none}}@media (min-width:769px){.show-tablet{display:none}}@media (prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}@media print{.no-print{display:none!important}}.dark .card-elevated{background:var(--bg-secondary);border-color:var(--border-primary)}.dark .glass{background:rgba(0,0,0,.3);border-color:rgba(255,255,255,.1)}.katex{font-size:1.2em;color:inherit}.katex-display{margin:1em 0;overflow-x:auto;overflow-y:hidden;padding:.5em 0}.prose .katex{color:inherit}.math-preview .katex{font-size:1.15em}.prose .katex-display{margin-top:1em;margin-bottom:1em}.dark .katex{color:inherit}.ai-example-card .katex{font-size:1.2em}.ai-formula-card .katex-display{font-size:1.3em;padding:1em 0}.ai-step-card .katex{font-size:1.15em}.katex-inline{margin:0 .15em}@media (max-width:640px){.katex{font-size:1.1em}.katex-display{padding:.5em;overflow-x:auto}.katex-display,.math-preview .katex{font-size:1.05em}}