:root {
    color-scheme: dark;
    --glow: #ff6b1a;
    --ink: #d8cec6;
    --muted: #8a7f78;
    --line: #2a2320;
    --bg: #070605;
    font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
    margin: 0;
    color: var(--ink);
    background: var(--bg);
    padding-inline: max(16px, env(safe-area-inset-left, 0px));
}

a { color: var(--glow); }
.mono { white-space: nowrap; }
.mono, kbd, code { font-family: ui-monospace, "JetBrains Mono", Menlo, Consolas, monospace; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }

button {
    font: inherit;
    font-size: 0.9rem;
    color: var(--ink);
    background: #14100e;
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: 0.4em 1em;
    cursor: pointer;
}
button:hover { border-color: color-mix(in srgb, var(--glow) 45%, var(--line)); }
button:focus-visible, input:focus-visible { outline: 2px solid var(--glow); outline-offset: 2px; }
button[aria-pressed="true"], button[aria-expanded="true"] {
    color: #fff;
    border-color: var(--glow);
    background: color-mix(in srgb, var(--glow) 18%, #14100e);
}
kbd {
    font-size: 0.75em;
    color: var(--muted);
    border: 1px solid var(--line);
    border-radius: 4px;
    padding: 0 0.35em;
    margin-left: 0.3em;
}

/* --- top bar and settings ------------------------------------------------- */
.bar {
    position: absolute;
    inset: 0 0 auto 0;
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: calc(12px + env(safe-area-inset-top, 0px)) max(16px, env(safe-area-inset-right, 0px)) 12px max(16px, env(safe-area-inset-left, 0px));
}
.mark { letter-spacing: 0.32em; text-transform: uppercase; font-size: 0.78rem; color: var(--muted); }
.tools { display: flex; gap: 8px; flex-wrap: wrap; justify-content: flex-end; }

.settings {
    position: absolute;
    z-index: 3;
    top: calc(60px + env(safe-area-inset-top, 0px));
    right: max(16px, env(safe-area-inset-right, 0px));
    width: min(300px, calc(100vw - 32px));
    padding: 16px;
    background: #110d0bf2;
    border: 1px solid var(--line);
    border-radius: 14px;
    display: grid;
    gap: 12px;
}
.settings fieldset { border: 0; margin: 0; padding: 0; }
.settings legend { font-size: 0.85rem; color: var(--muted); margin-bottom: 8px; }
.swatches { display: flex; gap: 8px; flex-wrap: wrap; }
.swatches button {
    width: 30px;
    height: 30px;
    padding: 0;
    background: var(--c);
    box-shadow: 0 0 10px color-mix(in srgb, var(--c) 60%, transparent);
}
.swatches button[aria-pressed="true"] { outline: 2px solid #fff; outline-offset: 2px; }
.row { display: flex; align-items: center; gap: 10px; font-size: 0.9rem; }
.row input[type="range"] { flex: 1; accent-color: var(--glow); }
.row input[type="checkbox"] { accent-color: var(--glow); width: 18px; height: 18px; }

/* --- hero ----------------------------------------------------------------- */
.hero {
    min-height: 100svh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 18px;
    padding-block: 80px 48px;
    margin-inline: calc(-1 * max(16px, env(safe-area-inset-left, 0px)));
    padding-inline: max(16px, env(safe-area-inset-left, 0px));
    background: radial-gradient(ellipse 70% 45% at 50% 48%, color-mix(in srgb, var(--glow) 7%, #0e0c0b), var(--bg) 70%);
}
.meter {
    width: min(1100px, 100%, (100svh - 260px) * 3.73);
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}
.meter svg { display: block; width: 100%; height: auto; overflow: visible; }
.caption { margin: 0; color: var(--muted); letter-spacing: 0.04em; text-align: center; }
#date:not(:empty)::before { content: " · "; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; justify-content: center; }
.hint { margin: 0; font-size: 0.85rem; color: #5f5651; text-align: center; }

/* --- desk mode: just the meter --------------------------------------------- */
body.desk { cursor: none; overflow: hidden; }
body.desk.awake { cursor: auto; }
body.desk .hero { min-height: 100vh; background: #000; padding-block: 0; }
body.desk .meter { width: min(100%, 100vh * 3.73); }
body.desk main > section:not(.hero), body.desk footer,
body.desk .caption, body.desk .actions, body.desk .hint { display: none; }
body.desk .bar { opacity: 0; transition: opacity 0.4s; }
body.desk.awake .bar { opacity: 1; }

/* --- inside a tube -------------------------------------------------------- */
main > section:not(.hero) { max-width: 980px; margin-inline: auto; padding-block: 72px; border-top: 1px solid #1a1513; }
h2 { font-weight: 500; font-size: 1.5rem; margin: 0 0 12px; color: #efe6df; }
.inside { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 40px; align-items: center; }
.inside p { color: #b3a8a0; }
.stage3d { perspective: 1100px; display: grid; place-items: center; min-height: 440px; }
.tube3d {
    position: relative;
    width: min(230px, 56vw);
    aspect-ratio: 140 / 240;
    transform-style: preserve-3d;
    transition: transform 0.9s cubic-bezier(0.3, 0.7, 0.2, 1);
}
.tube3d.apart { transform: rotateX(10deg) rotateY(-60deg); }
.layer {
    position: absolute;
    inset: 0;
    transform: translateZ(0);
    transition: transform 0.9s cubic-bezier(0.3, 0.7, 0.2, 1);
    pointer-events: none;
}
.tube3d.apart .layer { transform: translateZ(calc(var(--z) * 30px)); }
.layer svg { display: block; width: 100%; height: 100%; overflow: visible; }
.layer svg [pointer-events] { cursor: pointer; }
.tube3d.apart .cathode:not(.on) svg { filter: brightness(1.8); }
.label {
    position: absolute;
    right: -6%;
    top: 4%;
    font: 600 0.95rem ui-monospace, Menlo, monospace;
    color: var(--muted);
    opacity: 0;
    transition: opacity 0.4s;
}
.tube3d.apart .label { opacity: 1; }
.cathode.on .label { color: var(--glow); }
.tube3d.apart .glass, .tube3d.apart .shell { opacity: 0.85; }
svg.defs { position: absolute; width: 0; height: 0; }

/* --- install and footer --------------------------------------------------- */
.install p { color: #b3a8a0; }
pre {
    overflow-x: auto;
    background: #0f0c0a;
    border: 1px solid var(--line);
    border-radius: 10px;
    padding: 14px 16px;
    font-size: 0.9rem;
}
footer { max-width: 980px; margin: 0 auto; padding-block: 32px 48px; color: #5f5651; font-size: 0.85rem; border-top: 1px solid #1a1513; }
footer p { margin: 4px 0; }

@media (max-width: 720px) {
    .inside { grid-template-columns: 1fr; }
    .stage3d { min-height: 380px; }
    .hint { display: none; }
}

@media (hover: none) {
    kbd { display: none; }
}

@media (prefers-reduced-motion: reduce) {
    .tube3d, .layer { transition: none; }
}