can you make this look better and more modern 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>DiscordTools</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #0f0f0f;
            color: #ffffff;
            margin: 0;
            padding: 0;
        }
        .header {
            background-color: #1a1a1a;
            padding: 15px;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        .logo {
            font-size: 20px;
            font-weight: bold;
            color: #ffffff;
        }
        .banner {
            background-color: #6a0dad;
            color: #ffffff;
            padding: 10px;
            text-align: center;
            margin-top: 50px;
            font-size: 14px;
        }
        .content {
            padding: 15px;
            margin-top: 20px;
            overflow-y: auto;
            height: calc(100vh - 120px);
        }
        .product-card {
            background-color: #1a1a1a;
            border-radius: 10px;
            padding: 20px;
            margin-bottom: 15px;
        }
        .product-title {
            font-size: 20px;
            margin-bottom: 5px;
            color: #ff69b4;
        }
        .product-price {
            font-size: 16px;
            color: #ffffff;
            margin-bottom: 10px;
        }
        .purchase-button {
            background-color: #6a0dad;
            color: #ffffff;
            border: none;
            padding: 10px 0;
            border-radius: 5px;
            cursor: pointer;
            width: 100%;
            font-size: 16px;
        }
        .tab-bar {
            display: flex;
            justify-content: space-around;
            background-color: #1a1a1a;
            padding: 10px 0;
            position: sticky;
            top: 50px;
            z-index: 999;
        }
        .tab {
            color: #ffffff;
            text-decoration: none;
            padding: 5px 10px;
            border-radius: 5px;
            font-size: 14px;
        }
        .tab.active {
            background-color: #6a0dad;
        }
    </style>
</head>
<body>
    <div class="header">
        <div class="logo">DiscordTOOLS</div>
    </div>
    <div class="banner">
        Thank you for using our service!
    </div>
    <div class="tab-bar">
        <a href="#" class="tab">All prices are 60% off!</a>
    </div>
    <div class="content">
        <div class="product-card">
            <div class="product-title">NITRO TOKENS</div>
            <div class="product-price">Starting at: $0.80</div>
            <a href="https://ko-fi.com/plainapis"><button class="purchase-button">Purchase</button></a>
        </div>
        <div class="product-card">
            <div class="product-title">SERVER BOOSTS</div>
            <div class="product-price">Starting at: $4.50</div>
            <a href="https://ko-fi.com/plainapis"><button class="purchase-button">Purchase</button></a>
        </div>
        <div class="product-card">
            <div class="product-title">DISCORD MEMBERS</div>
            <div class="product-price">Starting at: $0.02</div>
            <a href="https://ko-fi.com/plainapis"><button class="purchase-button">Purchase</button></a>
        </div>
    </div>
</body>
</html>