<!DOCTYPE html>
<html lang="de">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Instagram 2.0</title>
    <style>
:root{
   --bright: #e0c2a5;
   --brown: #684536;
   --background: #fffee9;
   --cream: #f3ecc5;
}
@font-face {
   font-family: Open Sans;
   src: url("https://fonts.googleapis.com/css2?family=Open+Sans:wght@300&display=swap");
}  
*{
  margin:0;
  padding:0;
  box-sizing:border-box;
}
body{
  display:flex;
  flex-direction:column;
  background:var(--background);
}
header {
  display:flex;
  flex-direction:row;
  justify-content:flex-start;
  margin-left:50px;
  padding: 30px 0;
}
header h1 {
  font-family: Open Sans;
  font-size: 40px;
}
nav ul {
  height: 60px;
  display: flex;
  flex-direction: row;
  justify-content: flex-start;
  background: var(--bright);
  margin-bottom: 3px;
  align-content: space-around;
  align-items: center;
}
nav ul li{
  flex:1;
  list-style:none;
  text-align:center;
}
nav ul li a{
  text-align:center;
  text-decoration:none;
  color:black;
  font-size:20px;
}
a:hover{
  color:var(--brown);  
}
div.label {   
  font-family: Open Sans;
  font-size: 20px;
  background:var(--bright);
  padding: 15px;
}
main{
  padding-top: 1%;
  display: flex;
  flex-direction:column;
}
.ueber {
  display: flex;
  flex-direction: column;
  align-items: center;
  height:90px;
  padding:30px 0 40px 0;
}
h2{
  font-family: Open Sans;
  font-size: 20px;
}
.line {
  display: flex;
  flex-direction: column;
  background: var(--cream);
  align-content: stretch;
  align-items: center;
  margin:5px 0;
}
p {
  font-family: Open Sans;
}
footer{
  display:flex;
}
      textarea{
        width:100%;
        min-height:100px;
      }
footer img{
  width:calc(100% / 3);
  text-align:center;
  max-height:50px;
}
    </style>
</head>
<body>
   <header>
      <h1> <a href="instagram-clone_schlachter.html"> Gramml</a></h1> 
   </header>
   <nav>
      <ul id="navibereich">
          <li id="navi01"> <a href="profil.html"> Mein Profil </a> </li>
          <li id="navi02"> <a href="instagram-clone_schlachter.html"> Entdecken</a> </li>
          <li id="navi03"> <a href="upload.html">Upload Picture</a> </li>
      </ul>
   </nav>
   <div class="label">
       <label>Suche:</label>
       <input id="textsuxhe" type="text"/>
   </div>
   <main>
     <div class="ueber">
        <h2>Lukas_W3br</h2> 
            <img src="images/profilpic.jpg" alt="Profil" title="Profil" height="150">
     </div>
     <div class="line" id="Eingabe">
        <div class="field">
           <input id="Vorname" type="text" name="Vorname" placeholder="Vorname" />
        </div>
        <div class="field">
           <input id="Nachname" type="text" name="Nachname" placeholder="Nachname" />
        </div>
        <div class="field">
           <input id="Geburtstag" type="date" name="Geburtstag">
        </div>
        <div class="line">
           <label>Über mich: </label> 
           <textarea name="uber" id="ueber" placeholder="Über mich:"> </textarea>
        </div>
        <div class="line">   
           <p> <input id="check" type="checkbox" name="AGB" value="News"> Datenschutzerklärung und AGB akzeptieren. </p> 
        </div>
        <div class="line">
           <button id="enter" class=" button" type="submit">Speichern</button>
        </div>
     </div>
   </main>
   <footer class="LukasBilder">
      <img src="images/hiking.webp" alt="Wanderung" title="Wanderung" height="150">
      <img src="images/yellow_jacked.webp" alt="Wanderung" title="Wanderung" width="250" height="150">
      <img src="images/dog_human.jpg" alt="Hund" title="Hund" width="250" height="150">
   </footer>
<script>
var VornameInput = document.getElementById("Vorname");
var NachnameInput = document.getElementById("Nachname");
var GeburtstagInput = document.getElementById("Geburtstag");
var ueberMichInput = document.getElementById("ueber");
var che= document.getElementById("check");
var minlenge=5;
var but=document.getElementById("enter");
but.addEventListener("click",function(){
  var error='';
    if (VornameInput.value=='') {
        //console.log("Vorname:", VornameInput.value);
        error+="\nBitte gebe dein Vorname ein ! ";
    }
    if (NachnameInput.value=='') {
        //console.log("Nachname:", NachnameInput.value);
        error+="\nBitte gebe dein Nachname ein ! ";
    }
    if (!GeburtstagInput.value) {
        // console.log("Geburtstag :", GeburtstagInput.value);
        error+="\nBitte gebe dein geburtstag ein ! ";
    }
    if (ueberMichInput.value=='') {
   // console.log('UeberMich: gebe mindestenst '+minlenge+' zeichen in über mich ein'); 
        error+='\nÜeber Mich: gebe mindestenst '+minlenge+' zeichen in über mich ein !';
    }else{
        var menge=lange();
        error+=menge;
    }
    function lange(){
       if(ueberMichInput.value.length<=minlenge){
          //console.log("Lenge text", ueberMichInput.value.length+1);
        return "\nDu must noch mindestens "+(minlenge-ueberMichInput.value.length+1)+" an zeichen Über dich angeben angeben !";
       }else{
       }
    }
    if(check.checked==false){
       error+="\nSie müssen die datenschutz checkbox noch anklicken !";
    }
    console.log(error+'='+error.length)
    if(error=='undefined' || error==null || error==''){
       
    alert('alle,daten richtig ausgefüllt');
    }else if(error.length>10){
        alert(error);
    }
})
</script>
</body>
</html>            
         
            
                           
        
            
                           
         

External Javascript and CSS