body {
    font-family: sans-serif;
    margin: 0;
    transition: background 0.4s, color 0.4s;
}

section {
    min-height: 100vh;
    padding: 100px 50px;
    border-bottom: 1px solid #ddd;
}


body.dark {
    background: #222;
    color: #fff;
}


.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: #333;
    z-index: 1000;
}
.navbar ul {
    display: flex;
    justify-content: center;
    list-style: none;
    padding: 15px;
    margin: 0;
}
.navbar a {
    color: white;
    text-decoration: none;
    padding: 8px 15px;
    margin: 0 5px;
}
.navbar a.active {
    background: red;
    border-radius: 4px;
}


.box-container { display: flex; gap: 20px; margin-top: 50px; }
.box {
    width: 150px; height: 150px;
    background: orange;
    display: flex; align-items: center; justify-content: center;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s;
}
.box.show { opacity: 1; transform: translateY(0); }


.jump {
    padding: 15px 30px;
    cursor: pointer;
}
@keyframes jumpKey {
    0% { transform: translateY(0); }
    50% { transform: translateY(-15px); }
    100% { transform: translateY(0); }
}
.animate { animation: jumpKey 0.5s ease-in-out; }


.circle {
    position: absolute;
    width: 30px; height: 30px;
    border-radius: 50%;
    background: red;
    pointer-events: none; 
    transition: transform 0.1s ease-out; 
}