问Css和Javascript无法加载到html中

EN

Failed to load resource: the server responded with a status of 404 (Not Found)
slider.js:1 Uncaught ReferenceError: $ is not defined
    at slider.js:1
main.js:1 Failed to load resource: the server responded with a status of 404 (Not Found)
countdown.js:26 Uncaught TypeError: Cannot set property 'innerHTML' of null
    at updateClock (countdown.js:26)
    at initializeClock (countdown.js:36)
    at countdown.js:41
main.js:1 Failed to load resource: the server responded with a status of 404 (Not Found)
slider.css:1 Failed to load resource: the server responded with a status of 404 (Not Found)

static
-->second
---->css
       >app
         slider.css
---->js
       >app
         slider.css

{% load static %}
<link rel="stylesheet" href="{% static 'second/css/app/slider.css' %}">
<script src="https://code.jquery.com/jquery-3.5.0.min.js" integrity="sha256-xNzN2a4ltkB44Mc/Jz3pT4iU1cmeR0FkXs4pru/JxaQ=" crossorigin="anonymous"></script>
<script src="{% static 'second/js/app/slider.js' %}"></script>
    <div class="container">
        <h3>Our  Partners</h3>
        <section class="customer-logos slider">
      <div class="slide"><img src="https://image.freepik.com/free-vector/luxury-letter-e-logo-design_1017-8903.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/3d-box-logo_1103-876.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/blue-tech-logo_1103-822.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/colors-curl-logo-template_23-2147536125.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/abstract-cross-logo_23-2147536124.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/football-logo-background_1195-244.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/background-of-spots-halftone_1035-3847.jpg"></div>
      <div class="slide"><img src="https://image.freepik.com/free-vector/retro-label-on-rustic-background_82147503374.jpg"></div>
   </section>
</div>

$(document).ready(function(){
    $('.customer-logos').slick({
        slidesToShow: 6,
        slidesToScroll: 1,
        autoplay: true,
        autoplaySpeed: 1500,
        arrows: false,
        dots: false,
        pauseOnHover: false,
        responsive: [{
            breakpoint: 768,
            settings: {
                slidesToShow: 4
            }
        }, {
            breakpoint: 520,
            settings: {
                slidesToShow: 3
            }
        }]
    });
});

h3{
  text-align:center;
  padding: 20px;
}
/* Slider */

.slick-slide {
    margin: 0px 20px;
}

.slick-slide img {
    width: 100%;
}

.slick-slider
{
    position: relative;
    display: block;
    box-sizing: border-box;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
            user-select: none;
    -webkit-touch-callout: none;
    -khtml-user-select: none;
    -ms-touch-action: pan-y;
        touch-action: pan-y;
    -webkit-tap-highlight-color: transparent;
}

.slick-list
{
    position: relative;
    display: block;
    overflow: hidden;
    margin: 0;
    padding: 0;
}
.slick-list:focus
{
    outline: none;
}
.slick-list.dragging
{
    cursor: pointer;
    cursor: hand;
}

.slick-slider .slick-track,
.slick-slider .slick-list
{
    -webkit-transform: translate3d(0, 0, 0);
       -moz-transform: translate3d(0, 0, 0);
        -ms-transform: translate3d(0, 0, 0);
         -o-transform: translate3d(0, 0, 0);
            transform: translate3d(0, 0, 0);
}

.slick-track
{
    position: relative;
    top: 0;
    left: 0;
    display: block;
}
.slick-track:before,
.slick-track:after
{
    display: table;
    content: '';
}
.slick-track:after
{
    clear: both;
}
.slick-loading .slick-track
{
    visibility: hidden;
}

.slick-slide
{
    display: none;
    float: left;
    height: 100%;
    min-height: 1px;
}
[dir='rtl'] .slick-slide
{
    float: right;
}
.slick-slide img
{
    display: block;
}
.slick-slide.slick-loading img
{
    display: none;
}
.slick-slide.dragging img
{
    pointer-events: none;
}
.slick-initialized .slick-slide
{
    display: block;
}
.slick-loading .slick-slide
{
    visibility: hidden;
}
.slick-vertical .slick-slide
{
    display: block;
    height: auto;
    border: 1px solid transparent;
}
.slick-arrow.slick-hidden {
    display: none;
}