html,body{height:100%;margin:0;font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background-color:#121212;color:#e0e0e0}body{display:flex;flex-direction:column}.card{background-color:#1e1e1e;border:1px solid #444444;border-radius:12px;box-shadow:0 4px 8px #00000080;padding:1.5rem;margin:1rem}.app-container{padding:2rem;max-width:1200px;margin:0 auto;width:100%;box-sizing:border-box}h1,h2,h3,h4{color:#fff;margin-top:0}.flex-center{display:flex;justify-content:center;align-items:center}.flex-column{display:flex;flex-direction:column}.spacer{flex:1}.btn{padding:.5rem 1rem;border-radius:4px;border:none;background-color:#3f51b5;color:#fff;cursor:pointer;transition:opacity .2s}.btn:hover{opacity:.8}.btn:disabled{background-color:#555;cursor:not-allowed}.btn_select{padding:.5rem 1rem;border-radius:4px;border:none;background-color:#1e1e1e;color:#fff;cursor:pointer;transition:opacity .2s}.btn_select:hover{opacity:.8}.btn_select:disabled{background-color:#555;cursor:not-allowed}