Код IT Загрузка примера кода…

HTML main.html 
<!DOCTYPE html>
<html lang="ru">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Progress bar</title>
  <style>
    body {
      margin: 0;
      min-height: 100dvh;
      display: grid;
      place-items: center;
      padding: 1rem;
      font-family: system-ui, sans-serif;
    }
    .progress {
      width: min(100%, 280px);
      height: 8px;
      background: #e2e8f0;
      border-radius: 999px;
      overflow: hidden;
    }
    .progress__bar {
      height: 100%;
      width: 0;
      background: linear-gradient(90deg, #22c55e, #16a34a);
      border-radius: inherit;
      animation: fillBar 2.5s ease-out forwards;
    }
    @keyframes fillBar {
      to { width: 75%; }
    }
  </style>
</head>
<body>
  <div class="progress" role="progressbar" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100" aria-label="Загрузка">
    <div class="progress__bar"></div>
  </div>
</body>
</html>
<!DOCTYPE html>
<html lang="ru">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Progress bar</title>
  <style>
    body {
      margin: 0;
      min-height: 100dvh;
      display: grid;
      place-items: center;
      padding: 1rem;
      font-family: system-ui, sans-serif;
    }
    .progress {
      width: min(100%, 280px);
      height: 8px;
      background: #e2e8f0;
      border-radius: 999px;
      overflow: hidden;
    }
    .progress__bar {
      height: 100%;
      width: 0;
      background: linear-gradient(90deg, #22c55e, #16a34a);
      border-radius: inherit;
      animation: fillBar 2.5s ease-out forwards;
    }
    @keyframes fillBar {
      to { width: 75%; }
    }
  </style>
</head>
<body>
  <div class="progress" role="progressbar" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100" aria-label="Загрузка">
    <div class="progress__bar"></div>
  </div>
</body>
</html>