我的网页在 HTML 中有标题，但不可见-PHP中文网问答

所以我刚刚开始编码，所以不要评判我。我试图使用 vs code 创建我的网站，我使用 html 和 css，但是我试图放在代码左上角的标题和按钮没有显示在浏览器上，我在网络上搜索并可以似乎不明白。我正在使用 google chrome 浏览器来调试我的代码。

这是 html 部分：

 /* This is a reset stylesheet to ensure consistency across different browsers */
 html, body, div, span, applet, object, iframe,
 h1, h2, h3, h4, h5, h6, p, blockquote, pre,
 a, abbr, acronym, address, big, cite, code,
 del, dfn, em, img, ins, kbd, q, s, samp,
 small, strike, strong, sub, sup, tt, var,
 b, u, i, center,
 dl, dt, dd, ol, ul, li,
 fieldset, form, label, legend,
 table, caption, tbody, tfoot, thead, tr, th, td,
 article, aside, canvas, details, embed, 
 figure, figcaption, footer, header, hgroup, 
 menu, nav, output, ruby, section, summary,
 time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 100%;
    font: inherit;
    vertical-align: baseline;
 }
 /* HTML5 display-role reset for older browsers */
 article, aside, details, figcaption, figure, 
 footer, header, hgroup, menu, nav, section {
    display: block;
 }
 body {
    line-height: 1;
 }
 ol, ul {
    list-style: none;
 }
 blockquote, q {
    quotes: none;
 }
 blockquote:before, blockquote:after,
 q:before, q:after {
    content: '';
    content: none;
 }
 table {
    border-collapse: collapse;
    border-spacing: 0;
 }
 /* Custom styles for the poster store website */
 body {
    font-family: 'Trebuchet MS', Arial, Helvetica, sans-serif;
    background-color: white;
    color: #333;
   }

 header {
    background-color: #87CEFA;
    color: white;
    text-align: center;
    padding: 1em;
   }
 .header-container {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100px;
   }
 header h1 {
    margin: 0;
    font-size: 2em;
   }
 header .subtext {
    display: block;
    font-size: 1em;
    font-style: italic;
    color: white;
    margin-top: 10px;
   }

  
  

 nav {
    background-color: #87CEFA;
    padding: 0.5em;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: fixed; /* this line adds */
    top: 0; /* this line adds */
    width: 100%; /* this line adds */
    z-index: 1; /* this line adds */
 }
 nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
 }
 nav li {
    margin-right: 1em;
 }
 nav a {
    color: white;
    text-decoration: none;
    font-weight: bold;
    transition: all 0.3s ease;
 }
 nav a:hover {
    color: #333;
 }

 /* Add this class to main section to create space for navigation bar */
 main {
    margin: 2em 0 0 0; /* this line changed */
 }


 main {
    margin: 2em;
 }

 section {
    margin-bottom: 2em;
 }

  h2 {
    margin-top: 1em;
    font-weight: normal;
 }

    ul {
    list-style-type: none;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    }
    
    li {
    margin-bottom: 1em;
    flex: 1 0 30%;
    }
    
    img {
    width: 100%;
    max-width: 200px;
    height: auto;
    }
    
    button {
        background-color: #87CEFA;
        color: white;
        padding: 0.5em 1em;
        border: none;
        font-weight: bold;
        transition: all 0.3s ease;
        cursor: pointer;
        border-radius: 5px;
        box-shadow: 0px 2px 3px #888888;
        text-transform: uppercase;
        font-size: 0.9em;
    }
    
    button:hover {
        background-color: #4169E1;
        box-shadow: 0px 4px 6px #888888;
    }

    .menu-icon {
        position: absolute;
        top: 20px;
        right: 20px;
        width: 40px;
        height: 30px;
        cursor: pointer;
    }
    .menu-icon:before,
    .menu-icon:after,
    .menu-icon div {
        position: absolute;
        top: 12px;
        right: 0;
        height: 3px;
        width: 30px;
        background: #333;
      }
    .menu-icon:before {
        transform: rotate(45deg);
      }
    .menu-icon:after {
        transform: rotate(-45deg);
      }

    
 .category-button {
    background-color: #87CEFA;
    color: white;
    padding: 0.5em 1em;
    border: none;
    font-weight: bold;
    transition: all 0.3s ease;
    cursor: pointer;
    border-radius: 5px;
    box-shadow: 0px 2px 3px #888888;
    text-transform: uppercase;
    font-size: 0.9em;
    margin-right: 1em;
    display: block;
 }

 .category-button:hover {
    background-color: #4169E1;
    box-shadow: 0px 4px 6px #888888;
 }

    
    
    footer {
    background-color: #87CEFA;
    text-align: center;
    padding: 0.5em;
    color: #333;
    }
    
    /* Media Queries */
    @media (max-width: 767px) {
    nav ul {
    flex-direction: column;
    }
    nav li {
    margin-bottom: 0.5em;
    }
    section {
    flex: 1 0 100%;
    }
    li {
    flex: 1 0 100%;
    }
    }



  
    Poster Store
    
  
  
    
      
           Poster Store
           Inspiring and New
      
        
    
       
      
    
      
        Featured Posters
        Poster Categories
        About Us
        Contact Us
      
    
    
      
        Featured Posters
        
          
            Poster 1
            
            Album cover poster
            
          
          
            Poster 2
            
            Album cover poster
            
          
          
            Poster 3
            
            Album cover poster
            
            

            Poster 4
            
            Poster
            
          
          
              Poster 5
              
              Poster
              
          
        
      
      
        Poster Categories
        
          Lol
          Category 2
          Category 3
        
      
      
        About Us
        A new poster store 
      
      
        Contact Us
        feridtalibli854@gmail.com
      
    
    
      Copyright ©2022 Poster Store

当我检查浏览器时，几乎没有什么东西上面有线条，例如我尝试一次更改页面的字体并使用它，但我认为这不是问题......

这是该部分（css）：

body {
    font-family: 'Trebuchet MS', Arial, Helvetica, sans-serif;
    background-color: white;
    color: #333;
   }

我试图在网页的中上位置看到这样的内容：“海报商店”和副文本“鼓舞人心且新颖”。

header { background-color: #87CEFA; color: white; text-align: center; padding: 1em; } .header-container { display: flex; align-items: center; justify-content: center; flex-direction: column; height: 100px; } header h1 { margin: 0; font-size: 2em; } header .subtext { display: block; font-size: 1em; font-style: italic; color: white; margin-top: 10px; }