Using springboot to do projects css and js can never be found

problem description

the environmental background of the problems and what methods you have tried

related codes

/ / Please paste the code text below (do not replace the code with pictures)
application.yml configuration

spring:
  thymeleaf:
    cache: false
    prefix: classpath:/templates/
    suffix: .ftl
    encoding: utf-8
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/wxdcxt?useUnicode=true&characterEncoding=utf-8
  jpa:
    show-sql: true
  jackson:
    default-property-inclusion: non_null
  mvc:
    static-path-pattern: /static/**
server:
  servlet:
    context-path: /sell







-sharp    springmvc/views uri
-sharpserver:
-sharp  servlet:
-sharp    context-path: /apache-tomcat-7.0.90

add.ftl partial code

<!DOCTYPE html>
<html lang="en" >
<head>

    <meta charset="utf-8">
    <title>686 Adminize</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="">
    <meta name="author" content="">

    <!-- Le styles -->
    <link href="http://fonts.googleapis.com/css?family=Oxygen|Marck+Script" rel="stylesheet" type="text/css">
    <link href="/css/bootstrap.css" rel="stylesheet">
    <link href="./css/font-awesome.css" rel="stylesheet">
    <link href="../css/admin.css" rel="stylesheet">

    <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
    <!--[if lt IE 9]>
    <script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
    <![endif]-->

Project directory is as follows
clipboard.png

what result do you expect? What is the error message actually seen?

many methods have been tried on the Internet, but

can"t be found all the time.
Jun.25,2021

since thymeleaf, is used, why not use @ {}
see https://blog.csdn.net/qq_3292. URL section

for details.
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3bb7b-2c2ce.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3bb7b-2c2ce.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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