如何在md-chips中更改占位符的字体颜色？

Question

这是我的代码。我有一个md-autocomplete，我想改变芯片占位符的字体颜色。

<md-chips flex class="md-accent" ng-model="vm.job.skills"
                  readonly="vm.isExpired"
                  md-autocomplete-snap
                  md-transform-chip="vm.transformSkillChip($chip)">
            <!-- Skill tags autocomplete -->
            <md-autocomplete class="md-accent" md-search-text="searchText"
                             md-items="item in vm.querySkills(searchText)"
                             md-item-text="item.name"
                             placeholder="Enter skill tags for search"
                             md-delay="200"
                             id="inputSkillTags">
                <span md-highlight-text="searchText">{{item.name}}</span>
            </md-autocomplete>
            <md-chip-template>
                <span class="md-body-1">{{$chip}}</span>
            </md-chip-template>
        </md-chips>