*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;line-height:1.6;transition:all .3s ease}.app{min-height:100vh;transition:all .3s ease}.header{padding:20px 40px;display:flex;justify-content:space-between;align-items:center;box-shadow:0 2px 10px #0000001a;transition:all .3s ease}.header h1{font-size:2rem;font-weight:700}.header-controls{display:flex;align-items:center;gap:20px}.theme-toggle{background:#fff3;border:1px solid rgba(255,255,255,.3);color:#fff;padding:8px 16px;border-radius:20px;cursor:pointer;font-size:14px;transition:all .3s ease}.theme-toggle:hover{background:#ffffff4d}.user-info{display:flex;align-items:center;gap:10px;color:#fff}.logout-btn{background:#fff3;border:1px solid rgba(255,255,255,.3);color:#fff;padding:6px 12px;border-radius:15px;cursor:pointer;font-size:12px;transition:all .3s ease}.logout-btn:hover{background:#ffffff4d}.main{padding:40px;max-width:1200px;margin:0 auto}.login-form{background:#fff;padding:40px;border-radius:20px;box-shadow:0 10px 30px #0000001a;text-align:center;max-width:400px;margin:0 auto}.login-form h2{margin-bottom:30px;color:#333;font-size:1.8rem}.login-form form{display:flex;flex-direction:column;gap:20px}.todo-app{background:#fff;padding:40px;border-radius:20px;box-shadow:0 10px 30px #0000001a}.todo-app h2{margin-bottom:30px;color:#333;font-size:1.8rem;text-align:center}.todo-form{display:flex;gap:15px;margin-bottom:30px}.todo-stats{display:flex;align-items:center;gap:20px;margin-bottom:20px;padding:15px;background:#f8f9fa;border-radius:10px;flex-wrap:wrap}.todo-stats span{font-weight:600;color:#555}.todo-list{display:flex;flex-direction:column;gap:10px}.todo-item{display:flex;align-items:center;gap:15px;padding:15px;border:1px solid #e9ecef;border-radius:10px;transition:all .3s ease}.todo-item:hover{box-shadow:0 2px 8px #0000001a}.todo-item.completed{background:#f8f9fa;opacity:.7}.todo-item.completed .todo-text{text-decoration:line-through;color:#6c757d}.checkbox{width:20px;height:20px;cursor:pointer}.todo-text{flex:1;font-size:16px;color:#333}.todo-date{font-size:12px;color:#6c757d;min-width:80px;text-align:right}.empty-state{text-align:center;padding:40px;color:#6c757d;font-style:italic}.input{padding:12px 16px;border:2px solid #e1e5e9;border-radius:8px;font-size:16px;transition:border-color .3s ease;flex:1}.input:focus{outline:none;border-color:#667eea}.btn{padding:12px 24px;border:none;border-radius:8px;font-size:16px;font-weight:600;cursor:pointer;transition:all .3s ease}.btn-primary{background:#667eea;color:#fff}.btn-primary:hover{background:#5a6fd8;transform:translateY(-1px)}.btn-danger{background:#dc3545;color:#fff}.btn-danger:hover{background:#c82333;transform:translateY(-1px)}.btn-small{padding:6px 12px;font-size:14px}@media (max-width: 768px){.header{padding:15px 20px;flex-direction:column;gap:15px}.header h1{font-size:1.5rem}.main{padding:20px}.todo-form{flex-direction:column}.todo-stats,.todo-item{flex-direction:column;align-items:flex-start;gap:10px}.todo-date{text-align:left}}.app[data-theme=dark]{background:#1a1a1a;color:#fff}.app[data-theme=dark] .login-form,.app[data-theme=dark] .todo-app{background:#2d2d2d;color:#fff}.app[data-theme=dark] .input{background:#3d3d3d;border-color:#555;color:#fff}.app[data-theme=dark] .input:focus{border-color:#8b5cf6}.app[data-theme=dark] .todo-item{background:#3d3d3d;border-color:#555}.app[data-theme=dark] .todo-stats{background:#3d3d3d}