Header gets cut off when viewing HTML file in browser

I've got an assignment for school to make an web page about your favourite artist, I choose Guns N' Roses and wrote this code. However when I save this as an .HTML file and open this in my browser and expand some of the summary's the header gets cut off and I can't scroll it back. how do I solve this?

 @charset "utf-8";
 *{
     margin: 0;
     padding: 0;
     box-sizing: border-box;
     font-family: 'Lato', sans-serif;
     font-family: 'Oswald', sans-serif;
}
 .wrapper{
     position: fixed;
     top: 0;
     left: 0;
     height: 100%;
     width: 100%;
    /*background: linear-gradient(-135deg, #c850c0, #4158d0);
    */
    /* background: linear-gradient(375deg, #1cc7d0, #2ede98);
     */
    /* background: linear-gradient(-45deg, #e3eefe 0%, #efddfb 100%);
    */
    /* clip-path: circle(25px at calc(0% + 45px) 45px);
     */
     background: #000;
     clip-path: circle(25px at calc(100% - 45px) 45px);
     transition: all 0.3s ease-in-out;
}
 #active:checked ~ .wrapper{
     clip-path: circle(75%);
}
 .menu-btn{
     position: absolute;
     z-index: 2;
     right: 20px;
    /* left: 20px;
     */
     top: 20px;
     height: 50px;
     width: 50px;
     text-align: center;
     line-height: 50px;
     border-radius: 50%;
     font-size: 20px;
     color: #fff;
     cursor: pointer;
    /*background: linear-gradient(-135deg, #c850c0, #4158d0);
    */
    /* background: linear-gradient(375deg, #1cc7d0, #2ede98);
     */
    /* background: linear-gradient(-45deg, #e3eefe 0%, #efddfb 100%);
     */
     background: #000;
     transition: all 0.3s ease-in-out;
}
 #active:checked ~ .menu-btn{
     color: #fff;
}
 #active:checked ~ .menu-btn i:before{
     content: "\f00d";
}
 .wrapper ul{
     position: absolute;
     top: 50%;
     left: 50%;
     transform: translate(-50%, -50%);
     list-style: none;
     text-align: center;
}
 .wrapper ul li{
     margin: 15px 0;
}
 .wrapper ul li a{
     text-decoration: none;
     font-size: 30px;
     font-weight: 500;
     padding: 5px 30px;
     color: #fff;
     border-radius: 50px;
     background: #000;
     position: relative;
     line-height: 50px;
     transition: all 0.3s ease;
}
 .wrapper ul li a:after{
     position: absolute;
     content: "";
     background: #fff;
     background: linear-gradient(#14ffe9, #ffeb3b, #ff00e0);
    /*background: linear-gradient(375deg, #1cc7d0, #2ede98);
    */
     width: 104%;
     height: 110%;
     left: -2%;
     top: -5%;
    /* if the font is 'Oswald'*/
     border-radius: 50px;
     transform: scaleY(0);
     z-index: -1;
     animation: rotate 1.5s linear infinite;
     transition: transform 0.3s ease;
}
 .wrapper ul li a:hover:after{
     transform: scaleY(1);
}
 .wrapper ul li a:hover{
     color: #fff;
}
 input[type="checkbox"]{
     display: none;
}
 .content{
     position: absolute;
     top: 50%;
     left: 50%;
     transform: translate(-50%, -50%);
     z-index: -1;
     text-align: center;
     width: 100%;
     color: #202020;
     font-size: 14px;
}
 .content .title{
     position: absolute;
     left: 23%;
     bottom: 104%;
     font-size: 40px;
}
 @keyframes rotate {
     0%{
         filter: hue-rotate(0deg);
    }
     100%{
         filter: hue-rotate(360deg);
    }
}
<!doctype html>
<html lang="nl-nl">
   <head>
      <meta charset="utf-8">
      <title>Overzicht werk</title>
      <link rel="icon" type="image/x-icon" href="gnr.png">
      <link href="https://fonts.googleapis.com/css2?family=Oswald&display=swap" rel="stylesheet">
      <link href="https://fonts.googleapis.com/css2?family=Lato&display=swap" rel="stylesheet">
      <link href="style.css" rel="stylesheet" type="text/css">
      <script src="https://kit.fontawesome.com/a076d05399.js"></script>
   </head>
   <body>
      <input type="checkbox" id="active">
      <label for="active" class="menu-btn"><i class="fas fa-bars"></i></label>
      <div class="wrapper">
         <ul>
            <li><a href="index.html">Homepage</a></li>
            <li><a href="Laatste-Nieuws.html">Laatste nieuws</a></li>
            <li><a href="Tour-Info.html">tour info</a></li>
            <li><a href="Fotoboek.html">Fotoboek</a></li>
            <li><a href="overzicht.html">Overzicht werk</a></li>
            <li><a href="Contact-Info.html">Contact</a></li>
         </ul>
      </div>
      <div class="content">
         <div class="title">
            <h4> Overzicht van het werk</h4>
            <h6>Guns n' Roses heeft 6 studioalbums, 1 verzamelalbum en 2 live albums</h6>
         </div>
         <details>
            <summary> Appetite for Destruction </summary>
            <h3><small>Appetite for destruction is het eerste studioalbum van Guns N' Roses. Dit album 
               werdt uitgebracht op 21 Juli 1987.<br>Op Appetite for destruction staan 12 nummers met een 
               speelduur van in totaal 52 minuten en 31 seconden.</small>
            </h3>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Welcome To The Jungle </li>
               <li> 2. It's So Easy </li>
               <li> 3. Nighttrain </li>
               <li>4. Out Ta Get Me </li>
               <li>5. Mr. Brownstone </li>
               <li> 6. Paradise City </li>
               <li> 7. My Michelle </li>
               <li> 8. Think About You </li>
               <li> 9. Sweet Child o' Mine </li>
               <li> 10. You're Crazy </li>
               <li> 11. Anything Goes </li>
               <li> 12. Rocket Queen </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>G N' R Lies</summary>
            <h3><small>G N' R Lies is het tweede studioalbum van Guns N' Roses. Dit album kwam uit in 
               1988.<br> Op G N' R Lies staan 8 nummers met een totale speelduur van 36 minuten en 8 
               seconden. 
               </small>
            </h3>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Reckless Life </li>
               <li> 2. Nice Boys</li>
               <li> 3. Move to the City </li>
               <li> 4. Mama Kin </li>
               <li> 5. Patience </li>
               <li> 6. Used to Love Her </li>
               <li> 7. You're Crazy </li>
               <li> 8. One in a Million </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Use Your Illusion I</summary>
            <h3><small>Use Your Illusion I is het derde studioalbum van Guns N' Roses. Dit album komt uit 
               in 1991 en werdt tegelijk uitgegeven met Use Your Illusion II.<br> Op Use Your Illusion I 
               staan 16 nummers met een totale speelduur van 76 minuten en 4 seconden. Ofwel 1 uur 14 minuten 
               en 4 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Right Next Door to Hell </li>
               <li> 2. Dust N Bones </li>
               <li> 3. Live and Let Die </li>
               <li> 4. Don't Cry </li>
               <li> 5. Perfect Crime </li>
               <li> 6. You Ain't the First </li>
               <li> 7. Bad Obsession </li>
               <li> 8. Back Off Bitch </li>
               <li> 9. Double Talkin' Jive </li>
               <li> 10. November Rain </li>
               <li> 11. The Garden </li>
               <li> 12. Garden of Eden </li>
               <li> 13. Don't Damn me </li>
               <li> 14. Bad Apples </li>
               <li> 15. Dead Horse </li>
               <li> 16. Coma </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Use Your Illusion II</summary>
            <h3><small>Use Your Illusion II komt dus ook uit 1991 aangezien dit tegelijk werdt uitgegeven 
               met Use Your Illusion I en is het vierde studioalbum van de bang.<br> Op Use Your Illusion II 
               staan 14 nummers met een totale speelduur van 75 minuten en 57 seconden. Ofwel 1 uur 15 
               minuten en 57 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Civil War </li>
               <li> 2. 14 Years </li>
               <li> 3. Yesterdays </li>
               <li> 4. Knockin' on Heavens Door </li>
               <li> 5. Get in the Ring </li>
               <li> 6. Shotgun Blues </li>
               <li> 7. Breakdown </li>
               <li> 8. Pretty Tied Up </li>
               <li> 9. Locomotive </li>
               <li> 10. So Fine </li>
               <li> 11. Estranged </li>
               <li> 12. You Could be Mine </li>
               <li> 13. Don't Cry </li>
               <li> 14. My World </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>The Spaghetti Incident</summary>
            <h3><small>The Spaghetti Incident? komt uit 1993 en is het vijfde studioalbum van Guns N' 
               Roses.<br> op The Spaghetti Incident? staan 13 nummers met een totale speelduur van 46 minuten 
               en 3 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Since I Don't Have You </li>
               <li> 2. New Rose </li>
               <li> 3. Down on the Farm </li>
               <li> 4. Human Being </li>
               <li> 5. Raw Power </li>
               <li> 6. Ain't It Fun </li>
               <li> 7. Buick Makane </li>
               <li> 8. Hair of the Dog </li>
               <li> 9. Attitude </li>
               <li> 10. Black Leather </li>
               <li> 11. You Can't Out Your Arms Around a Memory </li>
               <li> 12. I Don't Care About You </li>
               <li> 13. Look at Your Game, Girl </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Chinese Democracy</summary>
            <h3><small>Chinese Democracy is het zesde en tot nu toe laatste studioalbum van Guns N' Roses, 
               Chinese democracy werdt uitgebracht in 2008.<br>Op Chinese Democracy staan 14 nummers met een 
               totale speelduur van 71 minuten en 25 seconden. ofwel 1 uur 11 minuten en 25 seconden.</small> 
            </h3>
            <br>   
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Chinese Democracy </li>
               <li> 2. Shackler's Revenge </li>
               <li> 3. Better </li>
               <li> 4. Street of Dreams </li>
               <li> 5. If the World </li>
               <li> 6. There was a time </li>
               <li> 7. Catcher in the Rye </li>
               <li> 8. Scraped </li>
               <li> 9. Riad n' the bedouins </li>
               <li> 10. Sorry </li>
               <li> 11. I.R.S. </li>
               <li> 12. Madagascar </li>
               <li> 13. This I Love </li>
               <li> 14. Prostitute </li>
            </ul>
            <br>
            <br>
            <br>
         </details>
      </div>
   </body>
</html>

Put your header outside the element that contains the main content. Remove position: absolute;, top: 50%;, left: 50%;, transform: translate(-50%, -50%); from the .content class.

If you want to center the header, use text-align-last: center on the title class.

Here an example:

@charset "utf-8";
 *{
     margin: 0;
     padding: 0;
     box-sizing: border-box;
     font-family: 'Lato', sans-serif;
     font-family: 'Oswald', sans-serif;
}
 .wrapper{
     position: fixed;
     top: 0;
     left: 0;
     height: 100%;
     width: 100%;
    /*background: linear-gradient(-135deg, #c850c0, #4158d0);
    */
    /* background: linear-gradient(375deg, #1cc7d0, #2ede98);
     */
    /* background: linear-gradient(-45deg, #e3eefe 0%, #efddfb 100%);
    */
    /* clip-path: circle(25px at calc(0% + 45px) 45px);
     */
     background: #000;
     clip-path: circle(25px at calc(100% - 45px) 45px);
     transition: all 0.3s ease-in-out;
}
 #active:checked ~ .wrapper{
     clip-path: circle(75%);
}
 .menu-btn{
     position: absolute;
     z-index: 2;
     right: 20px;
    /* left: 20px;
     */
     top: 20px;
     height: 50px;
     width: 50px;
     text-align: center;
     line-height: 50px;
     border-radius: 50%;
     font-size: 20px;
     color: #fff;
     cursor: pointer;
    /*background: linear-gradient(-135deg, #c850c0, #4158d0);
    */
    /* background: linear-gradient(375deg, #1cc7d0, #2ede98);
     */
    /* background: linear-gradient(-45deg, #e3eefe 0%, #efddfb 100%);
     */
     background: #000;
     transition: all 0.3s ease-in-out;
}
 #active:checked ~ .menu-btn{
     color: #fff;
}
 #active:checked ~ .menu-btn i:before{
     content: "\f00d";
}
 .wrapper ul{
     position: absolute;
     top: 50%;
     left: 50%;
     transform: translate(-50%, -50%);
     list-style: none;
     text-align: center;
}
 .wrapper ul li{
     margin: 15px 0;
}
 .wrapper ul li a{
     text-decoration: none;
     font-size: 30px;
     font-weight: 500;
     padding: 5px 30px;
     color: #fff;
     border-radius: 50px;
     background: #000;
     position: relative;
     line-height: 50px;
     transition: all 0.3s ease;
}
 .wrapper ul li a:after{
     position: absolute;
     content: "";
     background: #fff;
     background: linear-gradient(#14ffe9, #ffeb3b, #ff00e0);
    /*background: linear-gradient(375deg, #1cc7d0, #2ede98);
    */
     width: 104%;
     height: 110%;
     left: -2%;
     top: -5%;
    /* if the font is 'Oswald'*/
     border-radius: 50px;
     transform: scaleY(0);
     z-index: -1;
     animation: rotate 1.5s linear infinite;
     transition: transform 0.3s ease;
}
 .wrapper ul li a:hover:after{
     transform: scaleY(1);
}
 .wrapper ul li a:hover{
     color: #fff;
}
 input[type="checkbox"]{
     display: none;
}
 .content{

     z-index: -1;
     text-align: center;
     width: 100%;
     color: #202020;
     font-size: 14px;
}

.title{
text-align-last: center;
}

}
 @keyframes rotate {
     0%{
         filter: hue-rotate(0deg);
    }
     100%{
         filter: hue-rotate(360deg);
    }
}
<!doctype html>
<html lang="nl-nl">
   <head>
      <meta charset="utf-8">
      <title>Overzicht werk</title>
      <link rel="icon" type="image/x-icon" href="gnr.png">
      <link href="https://fonts.googleapis.com/css2?family=Oswald&display=swap" rel="stylesheet">
      <link href="https://fonts.googleapis.com/css2?family=Lato&display=swap" rel="stylesheet">
      <link href="style.css" rel="stylesheet" type="text/css">
      <script src="https://kit.fontawesome.com/a076d05399.js"></script>
   </head>
   <body>
      <input type="checkbox" id="active">
      <label for="active" class="menu-btn"><i class="fas fa-bars"></i></label>
      <div class="wrapper">
         <ul>
            <li><a href="index.html">Homepage</a></li>
            <li><a href="Laatste-Nieuws.html">Laatste nieuws</a></li>
            <li><a href="Tour-Info.html">tour info</a></li>
            <li><a href="Fotoboek.html">Fotoboek</a></li>
            <li><a href="overzicht.html">Overzicht werk</a></li>
            <li><a href="Contact-Info.html">Contact</a></li>
         </ul>
      </div>
      <div class="title">
            <h4> Overzicht van het werk</h4>
            <h6>Guns n' Roses heeft 6 studioalbums, 1 verzamelalbum en 2 live albums</h6>
         </div>
      <div class="content">
         
         <details>
            <summary> Appetite for Destruction </summary>
            <h3><small>Appetite for destruction is het eerste studioalbum van Guns N' Roses. Dit album 
               werdt uitgebracht op 21 Juli 1987.<br>Op Appetite for destruction staan 12 nummers met een 
               speelduur van in totaal 52 minuten en 31 seconden.</small>
            </h3>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Welcome To The Jungle </li>
               <li> 2. It's So Easy </li>
               <li> 3. Nighttrain </li>
               <li>4. Out Ta Get Me </li>
               <li>5. Mr. Brownstone </li>
               <li> 6. Paradise City </li>
               <li> 7. My Michelle </li>
               <li> 8. Think About You </li>
               <li> 9. Sweet Child o' Mine </li>
               <li> 10. You're Crazy </li>
               <li> 11. Anything Goes </li>
               <li> 12. Rocket Queen </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>G N' R Lies</summary>
            <h3><small>G N' R Lies is het tweede studioalbum van Guns N' Roses. Dit album kwam uit in 
               1988.<br> Op G N' R Lies staan 8 nummers met een totale speelduur van 36 minuten en 8 
               seconden. 
               </small>
            </h3>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Reckless Life </li>
               <li> 2. Nice Boys</li>
               <li> 3. Move to the City </li>
               <li> 4. Mama Kin </li>
               <li> 5. Patience </li>
               <li> 6. Used to Love Her </li>
               <li> 7. You're Crazy </li>
               <li> 8. One in a Million </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Use Your Illusion I</summary>
            <h3><small>Use Your Illusion I is het derde studioalbum van Guns N' Roses. Dit album komt uit 
               in 1991 en werdt tegelijk uitgegeven met Use Your Illusion II.<br> Op Use Your Illusion I 
               staan 16 nummers met een totale speelduur van 76 minuten en 4 seconden. Ofwel 1 uur 14 minuten 
               en 4 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Right Next Door to Hell </li>
               <li> 2. Dust N Bones </li>
               <li> 3. Live and Let Die </li>
               <li> 4. Don't Cry </li>
               <li> 5. Perfect Crime </li>
               <li> 6. You Ain't the First </li>
               <li> 7. Bad Obsession </li>
               <li> 8. Back Off Bitch </li>
               <li> 9. Double Talkin' Jive </li>
               <li> 10. November Rain </li>
               <li> 11. The Garden </li>
               <li> 12. Garden of Eden </li>
               <li> 13. Don't Damn me </li>
               <li> 14. Bad Apples </li>
               <li> 15. Dead Horse </li>
               <li> 16. Coma </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Use Your Illusion II</summary>
            <h3><small>Use Your Illusion II komt dus ook uit 1991 aangezien dit tegelijk werdt uitgegeven 
               met Use Your Illusion I en is het vierde studioalbum van de bang.<br> Op Use Your Illusion II 
               staan 14 nummers met een totale speelduur van 75 minuten en 57 seconden. Ofwel 1 uur 15 
               minuten en 57 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Civil War </li>
               <li> 2. 14 Years </li>
               <li> 3. Yesterdays </li>
               <li> 4. Knockin' on Heavens Door </li>
               <li> 5. Get in the Ring </li>
               <li> 6. Shotgun Blues </li>
               <li> 7. Breakdown </li>
               <li> 8. Pretty Tied Up </li>
               <li> 9. Locomotive </li>
               <li> 10. So Fine </li>
               <li> 11. Estranged </li>
               <li> 12. You Could be Mine </li>
               <li> 13. Don't Cry </li>
               <li> 14. My World </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>The Spaghetti Incident</summary>
            <h3><small>The Spaghetti Incident? komt uit 1993 en is het vijfde studioalbum van Guns N' 
               Roses.<br> op The Spaghetti Incident? staan 13 nummers met een totale speelduur van 46 minuten 
               en 3 seconden.</small>
            </h3>
            <br>
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Since I Don't Have You </li>
               <li> 2. New Rose </li>
               <li> 3. Down on the Farm </li>
               <li> 4. Human Being </li>
               <li> 5. Raw Power </li>
               <li> 6. Ain't It Fun </li>
               <li> 7. Buick Makane </li>
               <li> 8. Hair of the Dog </li>
               <li> 9. Attitude </li>
               <li> 10. Black Leather </li>
               <li> 11. You Can't Out Your Arms Around a Memory </li>
               <li> 12. I Don't Care About You </li>
               <li> 13. Look at Your Game, Girl </li>
            </ul>
         </details>
         <br>
         <br>
         <details>
            <summary>Chinese Democracy</summary>
            <h3><small>Chinese Democracy is het zesde en tot nu toe laatste studioalbum van Guns N' Roses, 
               Chinese democracy werdt uitgebracht in 2008.<br>Op Chinese Democracy staan 14 nummers met een 
               totale speelduur van 71 minuten en 25 seconden. ofwel 1 uur 11 minuten en 25 seconden.</small> 
            </h3>
            <br>   
         </details>
         <details>
            <summary>Tracklist</summary>
            <ul>
               <li> 1. Chinese Democracy </li>
               <li> 2. Shackler's Revenge </li>
               <li> 3. Better </li>
               <li> 4. Street of Dreams </li>
               <li> 5. If the World </li>
               <li> 6. There was a time </li>
               <li> 7. Catcher in the Rye </li>
               <li> 8. Scraped </li>
               <li> 9. Riad n' the bedouins </li>
               <li> 10. Sorry </li>
               <li> 11. I.R.S. </li>
               <li> 12. Madagascar </li>
               <li> 13. This I Love </li>
               <li> 14. Prostitute </li>
            </ul>
            <br>
            <br>
            <br>
         </details>
      </div>
   </body>
</html>