html,
body {
    margin: 0;
}

/* ---- Экраны (контент) ---- */
section {
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: .6rem;
    font-size: 2.2rem;
    color: #fff;
    text-align: center;
}

#screen1 {
    background: #008059;
}

#screen2 {
    background: #3498db;
}

#screen3 {
    background: #2ecc71;
}

#screen4 {
    background: #4a1d3a;
}

/* ---- topmenu: верхняя навигация (glass-бар) ---- */
#screen1 { position: relative; } /* якорь для absolute-бара */

.topmenu {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    display: flex;
    align-items: center;
    gap: var(--space-4);
    height: var(--nav-height);
    padding-inline: clamp(1.5rem, 6vw, 3rem);
    background: var(--color-nav-bg);
    backdrop-filter: blur(12px) saturate(1.2);
    border-bottom: 1px solid var(--color-border);
    font-family: var(--font-family-base);
}

.topmenu .brand {
    font-size: var(--font-size-h3);
    font-weight: 600;
    letter-spacing: 0.1em;
    color: var(--color-brand);
}

.topmenu .right-buttons {
    list-style: none;
    display: flex;
    gap: var(--space-2);
    margin: 0 0 0 auto;
    padding: 0;
}

.topmenu .right-buttons li a {
    position: relative;
    font-size: var(--font-size-small);
    color: var(--color-text-muted);
    text-decoration: none;
    padding: 0.35em 0.25em; /* зона ховера */
    transition: color var(--duration-fast) var(--ease-out);
}

.topmenu .right-buttons li a::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 1px;
    background: var(--color-accent);
    transform: scaleX(0);
    transition: transform var(--duration-fast) var(--ease-out);
}

.topmenu .right-buttons li a:hover {
    color: var(--color-text);
}

.topmenu .right-buttons li a:hover::after,
.topmenu .right-buttons li a:focus-visible::after {
    transform: scaleX(1);
}

.topmenu .right-buttons li a:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

@media (max-width: 640px) {
    .topmenu {
        flex-wrap: wrap;
        height: auto;
        padding-block: var(--space-2);
    }
}


.description-intro {
    padding: 5rem 1rem 1rem 1rem;
    text-align: left;
    font-size: 1.4rem;
    font-family: 'Trebuchet MS', 'Lucida Sans Unicode', 'Lucida Grande', 'Lucida Sans', Arial, sans-serif;
}