Эффект :hover и flex-элементы

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Навигационна панель</title>
    <style>
    body {
        margin: 0;
        padding: 0;
        background-color: #775ada;
        height: 100vh;
    }
    nav {
        width: 100%;
        background-color: #ff304f;
        text-align: end;
    }

    nav > a {
        display: inline-block;
        padding: 1em .75em;
        color: white;
        font-size: 1.25em;
        font-weight: bold;
        text-decoration: none;
    }
    h1 {
        color: white;
    }
    </style>
</head>
<body>
    <nav>
        <a href="" class="nav">О нас</a>
        <a href="" class="nav">О нас</a>
        <a href="" class="nav">О нас</a>
    </nav>
    <h1>Используйте display: inline-block;</h1>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>:hover</title>
    <style>
        body {
            margin: 0;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            background-color: #43dde6;
        }
        span {
            color: #fc5185;
            font-size: 4em;
            transition: all ease-in-out .15s;
            cursor: pointer;
        }
        span:hover {
            transform: scale(1.4);
            color: #f4fa9c;
        }
    </style>
</head>
<body>
    <span>H</span>
    <span>O</span>
    <span>V</span>
    <span>E</span>
    <span>R</span>
    <span>M</span>
    <span>E</span>
</body>
</html>

<!DOCTYPE html>
<html lang="ru">
<head>
    <meta charset="UTF-8">
    <title>Моя страница</title>
    <style>

        .btn { background-color: #19b8a6; color: white; border: 0; padding: 16px 32px; font-size: 20px; border-radius: 12px;
               cursor: pointer; transition: background-color 0.3s; }
        .btn:hover { background-color: #6d4aff; }
    </style>
</head>
<body>
    <button class="btn">Нажми меня</button>
</body>
</html>

<!DOCTYPE html>
<html lang="ru">
<head>
    <meta charset="UTF-8">
    <title>Моя страница</title>
    <style>

        body { padding: 40px; font-family: sans-serif; }
        .card { width: 220px; padding: 20px; border-radius: 16px; background-color: white; border: 1px solid #ddd; transition: all 0.25s; }
        .card:hover { transform: translateY(-10px); box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2); }
    </style>
</head>
<body>
    <div class="card">
        <h2>🐱 Котики</h2>
        <p>Наведи на меня мышку</p>
    </div>
</body>
</html>