:root {
    --gap: 1rem;
    --max-width: 900px;
    --button-min-width: 180px;
    --button-height: 60px;
    --accent: #1f8ef1;
    --radius: 12px;
}

body {
    margin: 0;
    padding: 0;
    font-family: "Times New Roman", "YuMincho", "Hiragino Mincho ProN", "Yu Mincho", "MS PMincho", serif;
    background-color: #171313;
    color: #aaaaaa;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    align-items: center;
    overflow-x: hidden;
}

body::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("../images/bg.png") repeat center top;
    z-index: -1;
}

header {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 80px 60px 40px;
}

header img {
    max-height: 100px;
    width: auto;
}

main {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px 30px;
    text-align: center;
}

h1 {
    margin: 0;
    font-size: 0; /* テキストの高さを消す（画像だけ見せたい場合） */
}

main h2 {
    font-size: 1.25em;
    letter-spacing: 0.12em;
    margin-top: 30px;
    margin-bottom: 10px;
}

.spaced-heading {
    margin-top: 80px;
}

p {
    font-size: 14px;
    letter-spacing: 0.05em;
}

video {
    max-width: 100%;
    max-height: 90vh;
    margin: 10px auto;
    border: 1px solid #585858;
    border-radius: 4px;
    background-color: #1b1717;
    display: block;
}

.card {
    width: 100%;
    max-width: var(--max-width);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-sizing: border-box;
}

/* buttons */
.btn-row {
    margin: 10px 0;
    width: 100%;
    display: flex;
    gap: var(--gap);
    align-items: stretch;
    justify-content: space-between;
    flex-wrap: wrap;
}

.download-btn {
    flex: 1 1 0;
    min-width: var(--button-min-width);
    height: var(--button-height);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    padding: 0.5rem 1rem;
    text-decoration: none;
    color: white;
    font-weight: 600;
    border-radius: 10px;
    border: 1px solid #585858;
    background: linear-gradient(180deg, #363333, #282626);
    box-shadow: 0 6px 14px rgba(76, 76, 76, 0.18), inset 0 -2px 0 rgba(0, 0, 0, 0.06);
    transition: transform 0.12s ease, box-shadow 0.12s ease, opacity 0.12s ease;
    user-select: none;
    white-space: nowrap;
}

/* --- ダウンロードボタンのホバー・アクティブ効果 --- */
.download-btn:hover {
    filter: brightness(1.1); /* 少し明るく */
    box-shadow: 0 8px 18px rgba(76, 76, 76, 0.25);
}

.download-btn:active {
    filter: brightness(0.9); /* 押し込み感 */
    box-shadow: 0 3px 8px rgba(0, 0, 0, 0.3) inset;
}

.download-btn:focus {
    outline: 3px solid rgba(31, 142, 241, 0.18);
    outline-offset: 3px;
}
.download-btn[aria-disabled="true"] {
    opacity: 0.6;
    pointer-events: none;
}

.download-btn .label {
    font-size: 1.25rem;
}
.download-btn .sub {
    font-size: 0.78rem;
    opacity: 0.9;
}

/* notes */
.note {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans JP", "Hiragino Kaku Gothic ProN",
        "Yu Gothic UI", sans-serif;
    text-align: left;
    display: inline-block;
    margin: 0 auto;
    font-size: 0.9rem;
    max-width: 100%;
}

/* footer */
footer {
    background-color: #241f1f;
    margin-top: 20px;
    padding: 15px 0 40px;
    text-align: center;
    font-size: 0.9em;
    width: 100%;
}

@media (max-width: 600px) {
    header {
        padding: 60px 60px 30px;
    }

    header img {
        max-height: 60px;
    }

    .btn-row {
        flex-direction: column;
    }

    .download-btn {
        flex-basis: 100%;
        min-width: 0;
    }

    .note {
        font-size: 0.8rem;
    }
}