html{box-sizing:border-box;font-size:100%}*,*:before,*:after{box-sizing:inherit;margin:0;padding:0}body{line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}img,picture,video,canvas,svg{display:block;max-width:100%}input,button,textarea,select{font:inherit}a{text-decoration:none;color:inherit}:root{--brand-primary:#1e293b;--brand-accent:#3b82f6;--brand-success:#10b981;--brand-surface:#f8fafc;--brand-text:#0f172a;--brand-text-muted:#64748b;--font-heading:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;--font-body:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;--space-xs:.5rem;--space-sm:1rem;--space-md:2rem;--space-lg:4rem;--space-xl:6rem}*{margin:0;padding:0;box-sizing:border-box}html{scroll-behavior:smooth}body{font-family:var(--font-body);line-height:1.6;color:var(--brand-text);background:#fff;-webkit-font-smoothing:antialiased}h1{font-size:clamp(2.5rem,5vw,4rem);line-height:1.1;font-weight:700;letter-spacing:-.02em;font-family:var(--font-heading)}.lead{font-size:clamp(1.125rem,2vw,1.25rem);line-height:1.7;color:var(--brand-text-muted);max-width:600px}.btn-primary{display:inline-flex;align-items:center;gap:.5rem;padding:1rem 2rem;background:var(--brand-accent);color:#fff;text-decoration:none;border-radius:.5rem;font-weight:600;transition:all .2s ease;border:none;cursor:pointer;font-size:1rem}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 10px 30px -10px rgba(59,130,246,.4)}.btn-secondary{display:inline-flex;align-items:center;gap:.5rem;padding:1rem 2rem;background:0 0;color:var(--brand-text);text-decoration:none;border-radius:.5rem;font-weight:600;border:2px solid var(--brand-text);cursor:pointer;transition:all .2s}.btn-secondary:hover{background:var(--brand-text);color:#fff}.logic-card{background:#fff;padding:2rem;border-radius:1rem;text-align:center;position:relative;border:1px solid #e2e8f0;transition:all .3s ease}.logic-card:hover{border-color:var(--brand-accent);transform:translateY(-4px);box-shadow:0 20px 40px -15px rgba(0,0,0,.1)}.logic-icon{width:48px;height:48px;margin:0 auto 1rem;color:var(--brand-accent)}.logic-equation{display:flex;align-items:center;justify-content:center;font-size:2rem;font-weight:300;color:var(--brand-text-muted);padding:0 1rem}.form-group{margin-bottom:1.5rem}.form-label{display:block;margin-bottom:.5rem;font-weight:600;font-size:.875rem;color:var(--brand-text)}.form-input{width:100%;padding:.875rem 1rem;border:2px solid #e2e8f0;border-radius:.5rem;font-size:1rem;font-family:inherit;transition:border-color .2s,box-shadow .2s}.form-input:focus{outline:none;border-color:var(--brand-accent);box-shadow:0 0 0 3px rgba(59,130,246,.1)}.form-input::placeholder{color:#94a3b8}.challenge-badge{display:inline-flex;align-items:center;gap:.5rem;background:linear-gradient(135deg,var(--brand-success),#059669);color:#fff;padding:.5rem 1rem;border-radius:2rem;font-size:.875rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;margin-bottom:1rem}.gradient-bg{background:linear-gradient(135deg,var(--brand-surface) 0%,#fff 100%)}.text-accent{color:var(--brand-accent)}.bg-surface{background:var(--brand-surface)}