.float-button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background-color: #4051b5;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
    z-index: 1000;
    transition: all 0.3s ease;
}

.float-button:hover {
    transform: scale(1.1);
    background-color: #303f9f;
}

.float-button i {
    font-size: 24px;
}

/* Desktop: hide the current-tab section header so nested first-level
   menus (V3测量流程 / iFace26 测量流程) sit at the top of the sidebar. */
@media screen and (min-width: 76.25em) {
    .md-sidebar--primary .md-nav__item--section > label.md-nav__link {
        display: none;
    }
}