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

/* Base body */
body {
    font-family: Arial, sans-serif;
    color: white;
    background: #111;
    min-height: 100vh;
}

/* Landing layout */
.landing {
    position: relative;
    min-height: 100vh;
    overflow: hidden;
}

/* Animated background layer */
.bg-layer {
    position: fixed;
    inset: 0;
    width: 120%;
    height: 120%;
    margin: auto;
    background-image: url('https://copilot.microsoft.com/th/id/BCO.d624965c-d5df-49fc-9271-c7c5a4b905ae.png');
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center;
    z-index: -2;              /* firmly behind everything */
    animation: drift 40s linear infinite alternate;
    pointer-events: none;     /* cannot block clicks */
}

/* Dark overlay */
.overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.55);
    z-index: -1;              /* behind content */
    pointer-events: none;
}

/* Background drift animation */
@keyframes drift {
    0% {
        transform: translate3d(-5%, -5%, 0) scale(1.05);
    }
    50% {
        transform: translate3d(5%, 3%, 0) scale(1.08);
    }
    100% {
        transform: translate3d(-3%, 5%, 0) scale(1.05);
    }
}

/* Header and navigation */
.header {
    position: relative;
    z-index: 10;
}

/* Nav bar */
.topnav {
    display: flex;
    justify-content: center;
    gap: 25px;
    padding: 15px 20px;
    background: rgba(0, 0, 0, 0.85);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
}

/* Base nav link style */
.topnav a {
    color: #ffffff;
    text-decoration: none;
    font-weight: bold;
    letter-spacing: 1px;
    text-transform: uppercase;
    font-size: 0.9rem;
    padding: 6px 10px;
    border-radius: 3px;
    background: transparent;
    border: 1px solid transparent;
    cursor: pointer;
    transition:
        background-color 0.15s ease,
        color 0.15s ease,
        border-color 0.15s ease,
        transform 0.1s ease;
}

/* Hover effect: clear and obvious */
.topnav a:hover {
    background-color: #ffffff;
    color: #000000;
    border-color: #ffffff;
    transform: translateY(-1px);
}

/* Click effect */
.topnav a:active {
    transform: translateY(1px) scale(0.97);
    opacity: 0.7;
}

/* Active page link */
.topnav a.active {
    border-color: #ffffff;
    background-color: rgba(255, 255, 255, 0.15);
}

/* Centered hero content */
.centered {
    position: relative;
    z-index: 5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 20px;
    /* space so content isn't hidden behind fixed nav */
    padding-top: 80px;
}

.centered h1 {
    font-size: 3rem;
    margin-bottom: 10px;
}

.centered p {
    font-size: 1.2rem;
    max-width: 600px;
}

/* Simple responsiveness */
@media (max-width: 600px) {
    .topnav {
        gap: 10px;
        padding: 10px 8px;
        flex-wrap: wrap;
    }

    .topnav a {
        font-size: 0.8rem;
        padding: 4px 8px;
    }

    .centered h1 {
        font-size: 2.2rem;
    }

    .centered p {
        font-size: 1rem;
    }
}