:root{--primary: #6366f1;--primary-hover: #4f46e5;--secondary: #ec4899;--background: #0f172a;--surface: #1e293b;--surface-hover: #334155;--text: #f8fafc;--text-muted: #94a3b8;--border: #334155;--success: #22c55e;--danger: #ef4444;--radius: 12px;--shadow: 0 10px 15px -3px rgba(0, 0, 0, .1), 0 4px 6px -2px rgba(0, 0, 0, .05);--font-sans: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif}*{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-sans);background-color:var(--background);color:var(--text);line-height:1.5;-webkit-font-smoothing:antialiased}button{cursor:pointer;font-family:inherit}input,select{font-family:inherit}h1,h2,h3,h4,h5,h6{font-weight:600;letter-spacing:-.025em}.container{max-width:1200px;margin:0 auto;padding:2rem}.card{background-color:var(--surface);border-radius:var(--radius);padding:1.5rem;box-shadow:var(--shadow);border:1px solid var(--border);transition:transform .2s ease,box-shadow .2s ease}.card:hover{transform:translateY(-2px);box-shadow:0 20px 25px -5px #0000001a,0 10px 10px -5px #0000000a}.btn{display:inline-flex;align-items:center;justify-content:center;padding:.5rem 1rem;border-radius:var(--radius);font-weight:500;transition:all .2s;border:none;outline:none}.btn-primary{background-color:var(--primary);color:#fff}.btn-primary:hover{background-color:var(--primary-hover)}.btn-danger{background-color:var(--danger);color:#fff}.btn-danger:hover{opacity:.9}.btn-ghost{background-color:transparent;color:var(--text-muted)}.btn-ghost:hover{background-color:var(--surface-hover);color:var(--text)}.input{width:100%;padding:.5rem .75rem;border-radius:var(--radius);background-color:var(--background);border:1px solid var(--border);color:var(--text);transition:border-color .2s}.input:focus{border-color:var(--primary);outline:none;box-shadow:0 0 0 2px #6366f133}.label{display:block;font-size:.875rem;font-weight:500;color:var(--text-muted);margin-bottom:.25rem}.fade-in{animation:fadeIn .5s ease-out forwards}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.app-header{text-align:center;margin-bottom:3rem}.app-title{font-size:2.5rem;background:linear-gradient(to right,var(--primary),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;margin-bottom:.5rem}.app-subtitle{color:var(--text-muted)}.dashboard-grid{display:grid;grid-template-columns:1fr;gap:2rem}@media(min-width:768px){.dashboard-grid{grid-template-columns:1fr 1fr}}.section-title{font-size:1.25rem;margin-bottom:1rem;display:flex;align-items:center;justify-content:space-between}.user-list{display:flex;flex-direction:column;gap:.5rem}.user-item{display:flex;align-items:center;justify-content:space-between;padding:.75rem;background-color:var(--background);border-radius:var(--radius);border:1px solid var(--border)}.expense-list{display:flex;flex-direction:column;gap:1rem}.expense-item{padding:1rem;background-color:var(--background);border-radius:var(--radius);border:1px solid var(--border)}.settlement-card{grid-column:1 / -1;background:linear-gradient(to bottom right,var(--surface),#1e1b4b)}.user-toggle-btn{display:inline-flex;align-items:center;justify-content:center;text-align:center;font-size:.875rem;padding:.25rem .75rem;border-radius:var(--radius);transition:all .2s;min-height:32px;line-height:1;cursor:pointer;font-family:inherit;font-weight:500}.user-toggle-btn.active{background-color:var(--primary);color:#fff;border:1px solid var(--primary)}.user-toggle-btn.inactive{background-color:transparent;color:var(--text-muted);border:1px solid var(--border)}.user-toggle-btn.inactive:hover{background-color:var(--surface-hover);color:var(--text);border-color:var(--text)}