body {
    background-color: #f0f2f5;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
}

.paper-doc {
    background: white;
    width: 400px;
    padding: 40px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    font-family: 'Noto Serif JP', serif;
    position: relative;
}

/* 承認ボタンエリア */
.approval-area {
    border: 2px solid #ddd;
    width: 80px;
    height: 80px;
    margin-left: auto;
    margin-top: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    cursor: pointer;
    transition: background 0.2s;
}
.approval-area:hover {
    background: #fafafa;
}
.approval-label {
    font-size: 0.7rem;
    color: #aaa;
    position: absolute;
    top: 2px;
    left: 2px;
}

/* ハンコ（印影） */
.hanko-mark {
    width: 60px;
    height: 60px;
    border: 3px solid #d32f2f; /* 朱色 */
    border-radius: 50%;
    color: #d32f2f;
    display: flex;
    flex-col;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-family: 'Hina Mincho', serif;
    font-weight: bold;
    font-size: 1.2rem;
    line-height: 1;
    position: absolute;

    /* 初期状態：非表示・拡大 */
    opacity: 0;
    transform: scale(3) rotate(-10deg);
    pointer-events: none;

    /* 乗算モードで紙に馴染ませる */
    mix-blend-mode: multiply;
}

/* かすれ表現（borderをラフに） */
.hanko-mark::after {
    content: '';
    position: absolute;
    inset: -2px;
    border: 2px solid transparent; /* 実際はmaskでかすれを表現するが今回は簡易的に */
    border-radius: 50%;
}

/* 捺印アニメーション */
.hanko-mark.stamped {
    animation: stamp-action 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

@keyframes stamp-action {
    0% { opacity: 0; transform: scale(3) rotate(-20deg); }
    50% { opacity: 1; transform: scale(0.9) rotate(-5deg); } /* 一瞬沈み込む */
    100% { opacity: 0.9; transform: scale(1) rotate(-8deg); } /* 定着 */
}

.btn-text {
    color: #ccc;
    font-size: 0.8rem;
}