Code Playground

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <DOCTYPE! html>
  <html lang="ru">
    <meta charset ="UTF-8">
    <title>simplecalc</title>
    </head>
  
  <body>
    <div class="container">
      <fieldset id="container">
        <form name="calculator">
          <input id="display" type="text" name="display" readonly>
          
          <input class="button digits" type="button" value="7">
          <input class="button digits" type="button" value="8">
          <input class="button digits" type="button" value="9">
          <input class="button mathButtons" type="button" value="+">
          <br />
          
          <input class="button digits" type="button" value="4">
          <input class="button digits" type="button" value="5">
          <input class="button digits" type="button" value="6">
          <input class="button mathButtons" type="button" value="-">
          <br />
          
           <input class="button digits" type="button" value="1">
           <input class="button digits" type="button" value="2">
           <input class="button digits" type="button" value="3">
          <input class="button mathButtons" type="button" value="x">
          <br />
          
          <input id="clearButton" class="button" type="button" value="C">
          <input class="button digits" type="button" value="0">
          <input class="button mathButtons" type="button" value="=">
          <input class="button mathButtons" type="button" value="/">
        </form>
      </fieldset>
    </div>
  </body>
  </html>
          
            
</body>
</html>

@charset "UTF-8";
@import url(https://fonts.googleapis.com/css?family=Nunito+Sans:300,400,600,700,800);
*,
:after,
:before {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}
body {
  background: url(https://i.pinimg.com/originals/dd/c8/d1/ddc8d103097e18e32e2cc568e37076b8.jpg);
background-color: #F2F2F2;
font-family: Tahoma;
}

.container {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  width: 100vw;
}

#container {
  width: 200px;
  padding: 8px 8px 20px 8px;
  margin: 20px auto;
  
  background-color: #ababab;
  border-radius: 4px;
  border-top: 2px solid #fff;
  border-right: 2px solid #fff;
  border-bottom: 2px solid #c1c1c1;
  border-left: 2px solid #c1c1c1;
  
  box-shadow: -3px 3px 7px rgba(0, 0, 0, .6), 
    inset -100px 0px 100px rgba(255, 255, 255, .5); 
}

#display {
  display: block;
  margin: 15px auto;
  height: 42px;
  width: 174px;
  padding: 0 10px;
  
  border-radius: 4px;
  border-top: 2px solid #211c1c;
  border-right: 2px solid #211c1c;
  border-bottom: 2px solid #040303;
  border-left: 2px solid #040303;
  
  background-color: #71817d;
  box-shadow: inset 0px 0px 10px #030303, 
    inset 0px -20px 1px rgba(75, 75, 75, 0.2);
  
  font-size: 28px;
  text-align: right;
  font-weight: 400;
}

.button {
  display: inline-block;
  margin: 2px;
  width: 42px;
  height: 42px;
  
  font-size: 16px;
  font-weight: bold;
  border-radius: 5px;
}

.mathButtons {
  margin: 2px 2px 6px 2px;
  color: #fff;
  text-shadow: -1px -1px 0px #44006f;
  background-color: #434343;
  
  border-top: 2px solid #c1c1c1;
  border-right: 2px solid #c1c1c1;
  border-bottom: 2px solid #181818;
  border-left: 2px solid #181818;
  
  box-shadow: 0px 0px 2px #030303,
    inset 0px -20px 1px #2e2e2e;
}

.digits {
  color: #181818;
  text-shadow: 1px 1px 0px #fff;
  background-color: #ebebeb;
  
  border-top: 2px solid #fff;
  border-right: 2px solid #fff;
  border-bottom: 2px solid #c1c1c1;
  border-left: 2px solid #c1c1c1;
  
  border-radius: 4px;
  
  box-shadow: 0px 0px 2px #030303, inset 0px -20px 1px #dcdcdc;
}

.clearButton {
  color: #fff;
  text-shadow: -1px -1px 0px #44006f;
  
  background-color: #d20000;
  
  border-top: 2px solid #ff8484;
   border-right: 2px solid #ff8484;
   border-bottom: 2px solid #800000;
   border-left: 2px solid #800000;
  
  box-shadow: 0px 0px 2px #030303, 
    inset 0px -20px 1px #b00000;
}

.digits:hover,
.mathButtons:hover,
#clearButtons:hover {
  background-color: #ffba75;
  
  box-shadow: 0px 0px 2px #ffba75,
    inset 0px -20px 1px #ff8000;
  border-top: 2px solid #fff;
  border-right: 2px solid #fff;
  border-bottom: 2px solid #ae5700;
  border-left: 2px solid #ae5700;
}

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