*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --header-height: clamp(4rem, 6vw, 5rem);
    --footer-height: clamp(3rem, 4vw, 4rem);
    --white: #fff;
    --black: #000;
    --letter-spacing: .1em;
}

body {
    min-height: 100dvh;
    overflow-x: hidden;
    color: var(--white);
    background: var(--white);
    line-height: 1.6;
    font-family: "Helvetica Neue", "Noto Sans JP", sans-serif;
}

header {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    padding: clamp(1rem, 2vw, 1.5rem) clamp(1.5rem, 4vw, 3rem);
    background: var(--white);
}

.logo img {
    height: var(--header-height);
}

nav {
    display: flex;
    gap: clamp(1rem, 2vw, 2rem);
}

nav a {
    color: var(--black);
    text-decoration: none;
    font-size: clamp(.75rem, 1vw, .9rem);
    letter-spacing: var(--letter-spacing);
    opacity: .8;
    transition: opacity .3s;
}

nav a:hover {
    opacity: 1;
}

section {
    min-height: calc(100dvh - var(--header-height));
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: clamp(2rem, 6vw, 5rem) clamp(1rem, 4vw, 3rem);
    gap: clamp(1.5rem, 3vw, 3rem);
}

section :is(h1, h2, h3) {
    transform: translateY(clamp(1.5rem, 3vw, 2.5rem));
}

section :is(p, a) {
    transform: translateY(clamp(2rem, 5vw, 4rem));
}

section :is(h1, h2, h3, p, a) {
    opacity: 0;
    transition: transform 1s ease, opacity .6s ease;
    will-change: transform, opacity;
}

section.show :is(h1, h2, h3, p, a) {
    transform: translateY(0);
    opacity: 1;
}

section h1 {
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 700;
}

section h2 {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 500;
}

section h3 {
    font-size: clamp(1rem, 2.75vw, 2.25rem);
    font-weight: 500;
}

section p {
    font-size: clamp(1rem, 1.6vw, 1.2rem);
    font-weight: 400;
}

section :is(h1, h2, h3, p) {
    letter-spacing: var(--letter-spacing);
}

.hero, .slide {
    background: center / cover no-repeat;
}

.slide {
    position: relative;
    min-height: 100dvh;
}

.slide a {
    width: clamp(8rem, 12vw, 10rem);
    padding: clamp(.7rem, 1.2vw, .9rem) clamp(1.6rem, 2.5vw, 2.5rem);
    color: var(--white);
    text-decoration: none;
    font-size: clamp(.75rem, 1vw, .85rem);
    letter-spacing: var(--letter-spacing);
    border: 1px solid rgba(255, 255, 255, 0.7);
    transition: background .35s, color .35s, border .35s, transform 1s ease, opacity .6s ease;
    will-change: background, color, border, transform, opacity;
}

.slide a:hover {
    background: var(--white);
    color: var(--black);
    border-color: var(--white);
    transform: translateY(-5px);
}

.sns {
    display: flex;
    gap: clamp(1rem, 2vw, 2rem);
}

footer {
    display: flex;
    justify-content: center;
    align-items: center;
    height: var(--footer-height);
    padding: clamp(1rem, 2vw, 2rem);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: clamp(.7rem, 1vw, .9rem);
    color: var(--black);
}