Animated Gradient Background in CSS

<script type="module" src="https://unpkg.com/ionicons@7.1.0/dist/ionicons/ionicons.esm.js"></script>
<script nomodule src="https://unpkg.com/ionicons@7.1.0/dist/ionicons/ionicons.js"></script>

<div class="gradient-background"></div>

<div class="content-card">
  <div class="icon-container">
    <ion-icon name="color-palette-outline"></ion-icon>
  </div>
  <h1>Animated Gradient Background</h1>
  <p>Experience smooth, professional gradient transitions with CSS animations. Perfect for modern web applications.</p>
  <button class="btn" onclick="changeGradient()">
    Change Animation Speed
  </button>
  <div class="info-text">
    <ion-icon name="information-circle-outline"></ion-icon>
    <span>Using color #aceca1</span>
  </div>
</div>

  * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow: hidden;
            position: relative;
        }

        .gradient-background {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: linear-gradient(45deg, #aceca1, #7fd87f, #aceca1, #5fc95f);
            background-size: 400% 400%;
            animation: gradientShift 15s ease infinite;
            z-index: -1;
        }

        @keyframes gradientShift {
            0% {
                background-position: 0% 50%;
            }
            50% {
                background-position: 100% 50%;
            }
            100% {
                background-position: 0% 50%;
            }
        }

        .content-card {
            background: rgba(255, 255, 255, 0.95);
            padding: 3rem 2.5rem;
            border-radius: 16px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            text-align: center;
            max-width: 500px;
            backdrop-filter: blur(10px);
        }

        .icon-container {
            font-size: 4rem;
            color: #aceca1;
            margin-bottom: 1.5rem;
            animation: float 3s ease-in-out infinite;
        }

        @keyframes float {
            0%, 100% {
                transform: translateY(0);
            }
            50% {
                transform: translateY(-10px);
            }
        }

        h1 {
            color: #2c3e50;
            font-size: 2rem;
            margin-bottom: 1rem;
            font-weight: 600;
        }

        p {
            color: #546e7a;
            font-size: 1rem;
            line-height: 1.6;
            margin-bottom: 2rem;
        }

        .btn {
            background: linear-gradient(135deg, #aceca1, #7fd87f);
            color: white;
            border: none;
            padding: 0.875rem 2rem;
            border-radius: 8px;
            font-size: 1rem;
            font-weight: 500;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: 0 4px 15px rgba(172, 236, 161, 0.3);
        }

        .btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(172, 236, 161, 0.4);
        }

        .btn:active {
            transform: translateY(0);
        }

        .info-text {
            margin-top: 2rem;
            font-size: 0.875rem;
            color: #78909c;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
        }

       let speed = 15;
        const gradientBg = document.querySelector('.gradient-background');
        
        function changeGradient() {
            speed = speed === 15 ? 8 : speed === 8 ? 25 : 15;
            gradientBg.style.animation = `gradientShift ${speed}s ease infinite`;
            
            const btn = document.querySelector('.btn');
            btn.textContent = speed === 15 ? 'Change Animation Speed' : 
                              speed === 8 ? 'Speed: Fast ⚡' : 'Speed: Slow 🐌';
        }