JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/autosize.js/3.0.20/autosize.min.js"></script>
<div id="app">
  <div class="container">
    <div class="input-container">
      <input type="text" placeholder="標題" v-model.trim="title">
      <textarea 
        placeholder="新增記事..." 
        v-model.trim="content"
        ref="content"
      ></textarea>
      <select class="color" v-model="color">
        <option value="" selected disabled>請選擇顏色</option>
        <option value="red">紅色</option>
        <option value="green">綠色</option>
        <option value="blue">藍色</option>
      </select>
    </div>    
    <button class="addBtn" @click="add">新增</button>
  </div>
  
  <div class="notes">
    <div 
      class="note" 
      v-for="(note, index) of notes" 
      :style="{ 'background-color': note.color }"
      :key = note.title
    >
      <h3 class="title">
        {{ note.title }}
      </h3>
      <p class="content">
        {{ note.content}}
      </p>
      <button class="deleteBtn" @click="del(index)">&#x2716;</button>
    </div>
  </div>
  
</div>

CSS

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  background-color: #202124;
}

#app {
  padding: 20px;
}

.container {
  display: flex;
  justify-content: center;
  max-width: 600px;
  margin: 0 auto 20px;
}

.input-container {
  display: flex;
  flex-direction: column;
  width: 500px;
}

.addBtn {
  flex-shrink: 0;
  border: 1px solid #5f6368;
  color: #5f6368;
  border-left: none;
  border-top-right-radius: 8px;
  border-bottom-right-radius: 8px;
  cursor: pointer;
  padding: 0 16px;
  transition: color 0.2s;
  font-size: 18px;
  font-weight: bold;
}

.addBtn:hover {
  color: #fff;
  white-space: nowrap;
}

input, textarea, .color {
  padding: 12px 16px;
  border: 1px solid #5f6368;
  outline: none;
  box-shadow: none;
  color: #fff;
  border-right: none;
}

input {
  font-size: 16px;
  font-weight: 500;
  border-bottom: none;
  border-top-left-radius: 8px;
}

textarea {
  font-size: 14px;
  /* height: 3rem; */
  border-top: none;
  border-bottom: none;
  resize: none;
  /* overflow: hidden; */
}

.color {
  border-top: none;
  border-bottom-left-radius: 8px;
  cursor: pointer;
}

.notes {
  display: grid;
  grid-template-columns: repeat(auto-fit, 240px);
  grid-gap: 16px;
  justify-content: center;
}

.note {
  width: 240px;
  border: 1px solid #5f6368;
  border-radius: 8px;
  padding: 12px 16px;
  font-size: 18px;
  color: #fff;
  position: relative;
}

.title {
  background-color: transparent;
  word-break: break-all;
}

.content {
  margin-top: 4px;
  background-color: transparent;
  word-break: break-all;
}

.deleteBtn {
  color: rgba(255, 255, 255, .7);
  background-color: transparent;
  border: none;
  position: absolute;
  font-size: 20px;
  top: 5px;
  right: 5px;
  cursor: pointer;
  transition: color .2s
}

.deleteBtn:hover {
  color: #fff;
}

JavaScript

const { createApp } = Vue

  createApp({
    data() {
      return {
      	title: '',
        content: '',
        color: '',
        notes: [
          {
            title: "春節行程安排",
            content: "吃飽睡，睡飽吃",
            color: "red",
          },
          {
            title: "工作待辦事項",
            content: "詢問各家廠商報價",
            color: "green",
          },
          {
            title: "運動健身計畫",
            content: "每天早上六點去健身",
            color: "blue",
          },
        ],
      };
    },
    methods: {
    	add() {
      	if (this.title === '' || this.content === '' || this.color === '') return;
        const newNote = {
        	title: this.title,
          content: this.content,
          color: this.color,
        };
        this.notes.push(newNote);
        this.title = '';
        this.content = '';
        this.color = '';
      },
      del(index) {
        this.notes.splice(index, 1);
      }
    },
    watch: {
    	notes: {
      	handler() {
        	localStorage.setItem('notesData',JSON.stringify(this.notes));          
        },
        deep: true,
      }
    },
    mounted() {
    	this.notes[0].content = '多出門、到處走走、也要多運動';
      if (localStorage.getItem('notesData')) {
      	this.notes = JSON.parse(localStorage.getItem('notesData'))
      }
      autosize(this.$refs.content);
    },
  }).mount('#app')