Hi, as for the first problem I see the problem in the import statement. The following snippet works fine:

<template>
  <div class="todo-item">
    <!-- Provides extra visual weight and identifies the primary action in a set of buttons -->
    <mdb-btn color="primary">Primary</mdb-btn>

    <!-- Default button -->
    <mdb-btn color="default">Default</mdb-btn>

    <!-- Secondary button -->
    <mdb-btn color="secondary">Secondary</mdb-btn>

    <!-- Indicates a successful or positive action -->
    <mdb-btn color="success">Success</mdb-btn>

    <!-- Contextual button for informational alert messages -->
    <mdb-btn color="info">Info</mdb-btn>

    <!-- Indicates caution should be taken with this action -->
    <mdb-btn color="warning">Warning</mdb-btn>

    <!-- Indicates a dangerous or potentially negative action -->
    <mdb-btn color="danger">Danger</mdb-btn>

    <mdb-btn color="primary"><mdb-icon icon="magic" class="mr-1"/> Left</mdb-btn>
    <mdb-btn color="default">Right <mdb-icon icon="magic" class="ml-1"/></mdb-btn>
  </div>
</template>

<script>
  import { mdbBtn } from 'mdbvue';

export default {
    name: "HelloWorld",
    props: ["todo"],
    methods:{
        markComplete(){
            this.todo.completed = !this.todo.completed
        }
    },
    components:{
        mdbBtn
    }
};

</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
  .todo-item{
    background: #f4f4f4;
    padding: 10px;
    border-bottom: 1px #ccc dotted;
}

.is-complete{
    text-decoration: line-through;
}

.del{
    background: #ff0000;
    color: #fff;
    border: none;
    padding: 5px 9px;
    border-radius: 50%;
    cursor: pointer;
    float: right;
}

</style>

As for the second problem it's quite hard to say anything without snippet from package.json. If you're still experiencing difficulties, please share the code (don't forget to remove your token). Kind regards, Magdalena

import Vue from 'vue' import 'bootstrap-css-only/css/bootstrap.min.css'; import 'mdbvue/build/css/mdb.css'; import App from './App.vue'

works for me.

Solved.