* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: #f4f5f7;
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px 16px;
    overflow-x: auto;
    width: 100%;
}

:root {
    --pageW: clamp(260px, 28vw, 400px);
    --pageH: calc(var(--pageW) * 1.414);
}

/* ----------------------------------
   PC用 観音折りスタイル
---------------------------------- */
.pc-viewer {
    position: relative;
    width: calc(var(--pageW) * 3);
    height: var(--pageH);
    perspective: 3000px;
    margin: 0 auto;
    flex-shrink: 0;
    cursor: pointer;
}

.pc-viewer .page {
    position: absolute;
    width: var(--pageW);
    height: var(--pageH);
    transition: 1.2s ease-in-out;
    transform-style: preserve-3d;
    backface-visibility: hidden;
    box-shadow: 0 15px 35px rgba(0,0,0,.15);
}

.pc-viewer .page img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    user-select: none;
    -webkit-user-drag: none;
}

.pc-viewer .cover { left: var(--pageW); z-index: 20; transform-origin: left center; }
.pc-viewer .service {
    left: 0;
    opacity: 0;

    /* Serviceは回転しないため3D描画を使用しない */
    transform-style: flat;
    backface-visibility: visible;
}
.pc-viewer .company { left: var(--pageW); opacity: 0; transform-origin: right center; }
.pc-viewer .strategy { left: calc(var(--pageW) * 2); opacity: 0; }
.pc-viewer .case, .pc-viewer .back { left: var(--pageW); opacity: 0; }

/* ----------------------------------
   スマホ用 スライドスタイル
---------------------------------- */
.mobile-container {
    width: 100%;
    max-width: 420px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.sp-viewer {
    position: relative;
    width: 100%;
    aspect-ratio: 1 / 1.414;
    background-color: #ffffff;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.12);
    overflow: hidden;
    cursor: pointer;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}

.sp-viewer img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: opacity 0.3s ease;
    -webkit-user-drag: none;
}

.page-number {
    display: none; /* ← 右上の〇/〇は非表示 */
    position: absolute;
    top: 12px;
    right: 12px;
    background: rgba(0, 0, 0, 0.55);
    color: #ffffff;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
    backdrop-filter: blur(4px);
}

/* ----------------------------------
   レスポンシブ切り替え (768px閾値)
---------------------------------- */
@media (max-width: 767px) {
    .pc-viewer { display: none !important; }
    .mobile-container { display: flex; }
}

@media (min-width: 768px) {
    .pc-viewer { display: block; }
    .mobile-container { display: none !important; }
}

/* ----------------------------------
   共通ボタンデザイン
---------------------------------- */
.buttons {
    margin-top: 24px;
    display: flex;
    justify-content: center;
    gap: 16px;
    width: 100%;
}

.btn {
    background: #1a1a1a;
    color: #ffffff;
    border: none;
    padding: 12px 28px;
    font-size: 14px;
    font-weight: 600;
    letter-spacing: 0.1em;
    border-radius: 30px;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    transition: all 0.25s ease;
    touch-action: manipulation;
}

.btn:hover { background: #333333; transform: translateY(-2px); }
.btn:active { transform: translateY(0); }

/* ----------------------------------
   ダウンロードボタン定義
---------------------------------- */
.download-container {
    margin-top: 20px;
    display: flex;
    justify-content: center;
    width: 100%;
}

.dl-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    background-color: #2b7d74; /* ボタン背景色（深緑） */
    color: #ffffff;
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
    padding: 10px 32px;
    border-radius: 50px; /* カプセル型デザイン */
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15); /* 下部シャドウ */
    transition: all 0.25s ease;
}

.dl-btn:hover {
    background-color: #236760;
    transform: translateY(-2px);
    box-shadow: 0 6px 14px rgba(0, 0, 0, 0.2);
}

.dl-btn:active {
    transform: translateY(0);
}

.dl-icon {
    width: 18px;
    height: 18px;
    stroke: currentColor;
}