:root {
    /* ヘキサゴンのサイズをCSS変数で一元管理 */
    --hex-width: 200px;
    /* 正確な高さを計算 (幅 * sqrt(3) / 2) */
    --hex-height: calc(var(--hex-width) * 0.866025);
}

body,
html {
    margin: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    /* background-color is handled by common.css to support theming */
    font-family: 'Arial', sans-serif;
}

/* ヘキサゴン背景 */
#hexagon-container {
    position: fixed;
    top: calc(var(--hex-height) / -4);
    left: calc(var(--hex-width) / -4);
    width: calc(100% + var(--hex-width));
    height: calc(100% + var(--hex-height));
    z-index: 1;
}

.hexagon {
    position: absolute;
    width: var(--hex-width);
    height: var(--hex-height);
    background-color: var(--grid-color);
    clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 50% 100%, 0% 75%, 0% 25%);
    transition: background-color 0.2s ease-in-out, transform 0.2s ease-in-out;
    will-change: background-color, transform;
}

.hexagon:hover {
    background-color: var(--header-accent-color);
}