.app{max-width:800px;margin:0 auto;padding:20px;font-family:Arial,sans-serif;display:flex;flex-direction:column;align-items:center;justify-content:flex-start}h1{text-align:center;color:#333}.step-list{list-style:none;padding:0;width:100%}.step{background:#f9f9f9;border-radius:8px;margin-bottom:15px;padding:15px;box-shadow:0 2px 4px #0000001a}.step-header{display:flex;align-items:center;gap:10px}.step-header h2{margin:0;font-size:1.5em;color:#333}.substep-list{list-style:none;padding:10px 0 0 30px}.substep{display:flex;align-items:center;gap:8px;margin-bottom:8px;font-size:1em;color:#555}.completed{text-decoration:line-through;color:#888}input[type=checkbox]{cursor:pointer}@media (max-width: 600px){.app{padding:10px}.step-header h2{font-size:1.2em}.substep{font-size:.9em}}