<p style="color: red; font-size: 20px;">이것은 빨간색 글씨입니다.</p>

<!DOCTYPE html>
<html>
<head>
    <style>
        p {
            color: green;
            font-size: 18px;
        }
    </style>
</head>
<body>
    <p>이것은 초록색 글씨입니다.</p>
</body>
</html>

/* styles.css */
h1 {
    color: blue;
    font-size: 30px;
}

<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" href="styles.css">
</head>
<body>
    <h1>CSS 예제</h1>
</body>
</html>