wxml:

<view class="section tc">
<video id="myVideo" src="http://wxsnsdy.tc.qq.com/105/20210/snsdyvideodownload?filekey=30280201010421301f0201690402534804102ca905ce620b1241b726bc41dcff44e00204012882540400&bizid=1023&hy=SH&fileparam=302c020101042530230204136ffd93020457e3c4ff02024ef202031e8d7f02030f42400204045a320a0201000400"
danmu-list="{{danmuList}}" enable-danmu danmu-btn controls autoplay="{{true}}"></video>
<view class="btn-area">

<input bindblur="bindInputBlur" />
<button bindtap="bindSendDanmu">发送弹幕</button>
</view>
</view>

<view class="tool">
<view class="tool-item" catchtap='Up' id="{{detail.id}}">
<image src="/images/icon/like.png" />
</view>
<view class="tool-item" catchtap='Comment' id="{{detail.id}}">
<image bindtap="bindReply" src="/images/icon/chat.png"></image>
</view>
</view>

<view class="comment_release">
<view class="left">
<textarea class="text" placeholder-class="weui-input" fixed="true" maxlength="-1" show-confirm-bar="false" cursor-spacing="15" auto-height="true" bindtap="bindReply" focus="{{releaseFocus}}" placeholder="写评论" />
<view class="line" />
</view>
<image class="emoji" src="/images/icon/emoji.png" />

<button bindtap="bindSendDanmu" class='submit'>发送弹幕</button>

</view>

CSS

.vbox {
margin-top: 120rpx;
/* border: 1px solid red; */
height: 100%;
width: 100%;
}

.section video{
/* border: 1px solid red; */
margin-top: 100rpx;
width: 100%;
}
.vbox video{
width: 100%;
}

/* 评论 /
/整体样式，就是黑色的容器/
.comment_release{
display: flex;
align-items: flex-end;
justify-content: space-between;
box-sizing: border-box;
position: fixed;
left: 0;
bottom: 0;
width: 100%;
padding: 8px 0 8px 13px;
background-color: #ffffff;
font-size: 12px;
z-index: 999;
}
/第一个红色的容器
大概想法就是给flex-direction赋一个colomn的值，并列放置
/
.comment_release.left{
display: flex;
flex-direction: column;
}
/输入框/
.comment_release .text{
width: 222px;
min-height: 17px;
max-height: 51px; /最多显示三行/
line-height: 17px;
font-size: 12px;
margin-bottom: 4px;
margin-left: 10px;
}
/线/
.comment_release .line{
margin-bottom: 0 ;
width: 222px;
height: 1rpx;
background-color: #4B5CD7;
}
/表情图标/
.comment_release .emoji{
width: 24px;
height: 24px;
line-height: 27px;
margin-right: 5px;
margin-left: 5px;
}
/发送按钮*/
.comment_release .submit{
width: 60px;
height: 27px;
line-height: 27px;
text-align: center;
margin-right: 10px;
background-color: #4B5CD7;
color: #ffffff;
font-size: 12px;
}

.tool{
height: 64rpx;
text-align: right;
line-height: 64rpx;
margin:20rpx 28rpx 20rpx 0;
}
.tool-item{
display: inline-block;
vertical-align: top;
margin-right: 30rpx;
}
.tool-item image{
height: 50rpx;
width: 50rpx;
}