.gh-root {
    --gh-mint: #66e4c4;
    --gh-ink: #15283b;
    position: relative;
    width: 100%;
    max-width: 960px;
    min-height: 540px;
    margin: 0 auto;
    overflow: hidden;
    border-radius: 18px;
    color: #edfaff;
    background:
        radial-gradient(circle at 15% 15%, rgba(102, 228, 196, .18), transparent 32%),
        radial-gradient(circle at 88% 78%, rgba(105, 145, 255, .2), transparent 34%),
        #091626;
    box-shadow: inset 0 0 0 1px rgba(255,255,255,.08), 0 18px 45px rgba(0,0,0,.35);
    user-select: none;
}
.gh-hud {
    display: grid;
    grid-template-columns: 1fr minmax(210px, 1.3fr) 1fr;
    align-items: center;
    gap: 14px;
    padding: 15px 22px 10px;
}
.gh-hud > div { display: flex; flex-direction: column; }
.gh-hud > div:last-child { align-items: flex-end; }
.gh-hud small, .gh-roundbar { font-size: .7rem; letter-spacing: .12em; color: #91aabd; }
.gh-hud strong { font: 800 1.65rem/1 var(--font-pixel, monospace); }
.gh-target-wrap { align-items: center; }
.gh-target-wrap b {
    display: grid;
    place-items: center;
    width: 78px;
    height: 58px;
    margin-top: 3px;
    border-radius: 15px;
    font: 900 2.55rem/1 "Noto Sans JP", sans-serif;
    color: #122636;
    background: linear-gradient(145deg, #f7ffff, var(--gh-mint));
    box-shadow: 0 0 24px rgba(102,228,196,.32);
}
.gh-timer-wrap strong.is-low { color: #ff6e8b; }
.gh-roundbar {
    display: flex;
    justify-content: center;
    gap: 24px;
    padding: 0 18px 11px;
}
.gh-roundbar b { color: #fff; }
.gh-difficulty { padding: 2px 9px; border-radius: 999px; color: #0b1a26; background: #9aeedb; }
.gh-difficulty.tier-1 { background: #ffe28b; }
.gh-difficulty.tier-2 { background: #ffad8c; }
.gh-difficulty.tier-3 { background: #d2a5ff; }
.gh-board {
    position: relative;
    width: calc(100% - 44px);
    height: 350px;
    margin: 0 22px;
    overflow: hidden;
    border-radius: 16px;
    background:
        radial-gradient(circle at 22% 18%, rgba(102,228,196,.11), transparent 24%),
        radial-gradient(circle at 80% 72%, rgba(94,139,235,.1), transparent 27%),
        linear-gradient(145deg, rgba(247,253,251,.98), rgba(232,244,241,.98));
    box-shadow: inset 0 0 0 1px rgba(255,255,255,.95), inset 0 0 35px rgba(31,95,83,.06);
}
.gh-cell {
    --gh-x: 50%;
    --gh-y: 50%;
    --gh-rot: 0deg;
    --gh-size: 24px;
    --gh-hit: 38px;
    --gh-zoom: 1;
    position: absolute;
    left: var(--gh-x);
    top: var(--gh-y);
    display: grid;
    width: var(--gh-hit);
    height: var(--gh-hit);
    place-items: center;
    padding: 0;
    border: 0;
    border-radius: 50%;
    color: var(--gh-ink);
    background: transparent;
    font: 700 var(--gh-size)/1 "Noto Sans JP", "Meiryo", sans-serif;
    cursor: pointer;
    transform: translate(-50%, -50%) rotate(var(--gh-rot)) scale(var(--gh-zoom));
    transition: transform .1s, color .1s, text-shadow .1s;
}
.gh-cell:hover, .gh-cell:focus-visible {
    z-index: 1;
    --gh-zoom: 1;
    outline: none;
    color: #071d19;
    text-shadow: 0 4px 12px rgba(23,70,92,.24);
}
.gh-cell:focus-visible { box-shadow: 0 0 0 3px rgba(75,120,232,.42); }
.gh-cell.is-wrong { color: #dc4860; animation: gh-pulse-wrong .26s ease; }
.gh-cell.is-correct { --gh-zoom: 1; color: #078264; text-shadow: 0 0 14px rgba(102,228,196,.8); }
@keyframes gh-pulse-wrong { 50% { filter: blur(.7px); } }
.gh-feedback { height: 30px; padding-top: 7px; text-align: center; font-weight: 800; color: var(--gh-mint); }
.gh-pause-button {
    position: absolute;
    top: 17px;
    right: 116px;
    width: 34px;
    height: 34px;
    border: 1px solid rgba(255,255,255,.18);
    border-radius: 10px;
    color: #fff;
    background: rgba(255,255,255,.07);
    cursor: pointer;
}
.gh-overlay {
    position: absolute;
    inset: 0;
    display: none;
    place-items: center;
    padding: 24px;
    z-index: 5;
    background: rgba(5,14,26,.88);
    backdrop-filter: blur(10px);
}
.gh-overlay.is-active { display: grid; }
.gh-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    width: min(520px, 100%);
    text-align: center;
}
.gh-eyebrow { color: var(--gh-mint); font: 700 .72rem/1 var(--font-pixel, monospace); letter-spacing: .16em; }
.gh-card h2 { margin: 0; font: 900 2.65rem/1 var(--font-display, sans-serif); }
.gh-card h2 span { color: var(--gh-mint); }
.gh-card p { max-width: 460px; margin: 0; color: #bcd0dd; }
.gh-card p strong, .gh-card li::marker { color: var(--gh-mint); }
.gh-card ul { margin: 0; padding-left: 1.25em; text-align: left; color: #dcebf2; line-height: 1.8; }
.gh-card button {
    padding: 12px 34px;
    border: 0;
    border-radius: 999px;
    color: #0b2130;
    background: linear-gradient(135deg, #baffee, var(--gh-mint));
    font-weight: 900;
    cursor: pointer;
}
.gh-card a { color: #9fd8ff; }
.gh-save { padding: 7px 13px; border-radius: 9px; background: rgba(255,255,255,.08); color: #c9dae4; }
@media (max-width: 620px) {
    .gh-root { min-height: 610px; border-radius: 12px; }
    .gh-hud { grid-template-columns: 1fr 1fr; }
    .gh-target-wrap { grid-column: 1 / -1; grid-row: 1; }
    .gh-board { width: calc(100% - 20px); height: 405px; margin: 0 10px; }
    .gh-roundbar { gap: 9px; font-size: .61rem; }
    .gh-pause-button { top: 74px; right: 15px; }
}
@media (prefers-reduced-motion: reduce) {
    .gh-cell { transition: none; }
    .gh-cell.is-wrong { animation: none; }
}