在元素前面移动md-subheader（z-index？）

Question

我刚刚开始进行网络开发，并认为自己在CSS和HTML方面都是新手。

在下面的代码段中，我无法让md-subheader移到md-fab-speed-dial之上。 md-fab-speed-dial可通过md-subheader点击md-subheader。如何移动前面的md-fab-speed-dial或移动<md-content style="height: 900px;" flex> <section> <md-subheader class="md-primary">Songs</md-subheader> <md-list layout-padding> <div layout="row" ng-repeat="song in songs"> <md-list-item class="md-3-line" ng-click="playSong(song)" flex> <div class="md-list-item-text" layout="column"> <h3>{{ song.title }}</h3> <h4>{{ song.album }}</h4> <p>{{ song.year }}</p> </div> </md-list-item> <md-fab-speed-dial md-direction="left" md-open="demo.isOpen" class="md-scale" ng-mouseenter="demo.isOpen=true" ng-mouseleave="demo.isOpen=false" style="position: relative;"> <md-fab-trigger> <md-button aria-label="menu" class="md-fab md-primary md-hue-3"> <md-icon md-svg-src="assets/icons/queue_music.svg" aria-label="plalist"></md-icon> </md-button> </md-fab-trigger> <md-fab-actions> <md-button aria-label="add-playlist" class="md-fab md-raised md-mini" ng-click=""> <md-tooltip md-direction="top" md-visible="tooltipVisible" md-autohide="false"> Add to playlist </md-tooltip> <md-icon md-svg-src="assets/icons/playlist_add.svg"></md-icon> </md-button> </md-fab-actions> </md-fab-speed-dial> </div> </md-list> </section> </md-content> 移动？

var opts = {
    strings: options.typed.strings,
    typeSpeed: options.typed.typeSpeed,
    backSpeed: options.typed.backSpeed,
    contentType: 'text',
    loop: true,
}
if(options.typed.callback)
    opts.callback = options.typed.callback
$(".code-animate").typed(opts);