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You can use this iPhone 6 mockup and Macbook Pro mockup to show off a responsive website. Here, a man is holding up his iPhone 6 while he is also working on his Macbook Pro. He is sitting at a wooden desk with an iMac nearby. The scene has dark lighting like he is working late. You can show off both your app and your site or a great responsive design. The iPhone 6 mockup holds an image of 750x1334px. The Macbook Pro mockup holds an image of 1280x800px.
Drag & drop not supported, but you can still upload via this input field: