:root {
    --bg: #000;
    --box1: #1c1c1e;
    --box2: #2c2c2e;
    --highlight: #0a84ff;
}

* {
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    margin: 0;
    background: var(--bg);
    font-family: -apple-system, BlinkMacSystemFont, sans-serif;
    color: white;
    animation: fadeIn 1s ease forwards;
    opacity: 0;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

.back-btn {
    position: fixed;
    top: 15px;
    left: 15px;
    background: var(--box1);
    color: white;
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    font-size: 20px;
    cursor: pointer;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    transition: background 0.3s ease;
}

.back-btn:hover {
    background: var(--highlight);
}

.logo {
    display: block;
    width: 50%;
    margin: 4vh auto;
}