:root {
    color-scheme: dark;
    --bg: #0B0C0A;
    --panel: #000000;
    --fg: #F4F4F0;
    --muted: #8A8F84;
    --rule: #2A2F26;
    --signal: #FFB800;
}

* {
    box-sizing: border-box;
}

html {
    min-height: 100%;
    background: var(--bg);
}

body {
    margin: 0;
    min-height: 100vh;
    min-height: 100svh;
    display: grid;
    place-items: center;
    padding: clamp(18px, 5vw, 64px);
    overflow: auto;
    background: var(--bg);
    color: var(--fg);
    font-family: "IBM Plex Mono", "JetBrains Mono", "Berkeley Mono", ui-monospace, SFMono-Regular, Consolas, monospace;
    font-variant-numeric: tabular-nums;
    text-rendering: geometricPrecision;
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    pointer-events: none;
    background:
        linear-gradient(var(--rule) 1px, transparent 1px),
        linear-gradient(90deg, var(--rule) 1px, transparent 1px);
    background-size: clamp(36px, 7vw, 72px) clamp(36px, 7vw, 72px);
    mask-image: radial-gradient(circle at center, black 0, transparent 70%);
    opacity: 0.42;
}

main {
    position: relative;
    width: min(100%, 1240px);
    min-height: min(620px, calc(100svh - clamp(36px, 10vw, 128px)));
    display: grid;
    place-items: center;
}

.notice {
    position: relative;
    width: min(100%, 1120px);
    display: grid;
    gap: clamp(28px, 4vw, 48px);
    padding: clamp(34px, 6vw, 76px) clamp(24px, 7vw, 92px);
    background: color-mix(in srgb, var(--panel) 86%, transparent);
    border: 1px solid var(--rule);
}

.notice::before,
.notice::after {
    content: "";
    position: absolute;
    left: clamp(20px, 6vw, 64px);
    right: clamp(20px, 6vw, 64px);
    height: 1px;
    background: var(--signal);
}

.notice::before {
    top: clamp(16px, 4vw, 34px);
}

.notice::after {
    bottom: clamp(16px, 4vw, 34px);
}

.domain {
    margin: 0;
    color: var(--signal);
    font-size: clamp(0.72rem, 1.7vw, 0.95rem);
    line-height: 1;
    letter-spacing: 0;
    text-transform: uppercase;
    text-align: center;
}

.letter {
    display: grid;
    gap: clamp(18px, 2.6vw, 30px);
    width: 100%;
    max-width: 940px;
    margin: 0 auto;
    text-align: left;
}

.salutation,
.body-copy,
.signature {
    margin: 0;
    color: var(--fg);
    font-size: clamp(1rem, 1.8vw, 1.35rem);
    line-height: 1.45;
    letter-spacing: 0;
}

.salutation,
.signature {
    color: var(--signal);
}

h1 {
    margin: 0;
    max-width: 100%;
    color: var(--fg);
    font-size: clamp(1.65rem, 3.15vw, 3.05rem);
    line-height: 1.18;
    font-weight: 700;
    letter-spacing: 0;
    text-wrap: pretty;
}

@media (max-width: 560px) {
    main {
        min-height: calc(100svh - 36px);
    }

    .notice {
        gap: 26px;
        padding: 44px 22px;
    }

    .letter {
        gap: 18px;
    }

    h1 {
        max-width: 100%;
        font-size: clamp(1.45rem, 7.4vw, 2.35rem);
        line-height: 1.22;
    }
}