.sticky-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: #fff;
    border-bottom: 3px solid #000;
    padding: clamp(0.75rem, 1.5vh, 1rem) clamp(1rem, 2vw, 2rem);
    display: none;
    align-items: center;
    justify-content: center;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.sticky-header.show {
    display: flex;
    opacity: 1;
    transform: translateY(0);
}

.sticky-header-content {
    max-width: 1200px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: clamp(1rem, 2vw, 1.5rem);
}

.sticky-header-title {
    font-size: clamp(1rem, 2.5vw, 1.3rem);
    font-weight: 700;
    color: #000;
    margin: 0;
}

.sticky-header-theme {
    font-size: clamp(0.85rem, 2vw, 1.1rem);
    font-weight: 500;
    color: #333;
    margin: 0;
    flex: 1;
    text-align: right;
}

@media (max-width: 768px) {
    .sticky-header-content {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .sticky-header-theme {
        text-align: left;
        font-size: clamp(0.8rem, 1.8vw, 1rem);
    }
}

/* sticky-headerの下辺に5クラスカラーストライプ */
.sticky-header::after {
    content: '';
    display: block;
    position: absolute;
    bottom: -5px;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(
        to right,
        #0066FF 0%, #0066FF 20%,
        #00C840 20%, #00C840 40%,
        #9B45F5 40%, #9B45F5 60%,
        #FF1C3A 60%, #FF1C3A 80%,
        #FF7A00 80%, #FF7A00 100%
    );
}

/* theme-descriptionのpadding-bottomのみ上書き */
.theme-description {
    padding-bottom: calc(clamp(2rem, 4vh, 2.5rem) + 15px);
}

.theme-content-wrapper {
    display: flex;
    flex-direction: column;
}

.groups-container {
    width: 100%;
    max-width: 1200px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: clamp(1rem, 2vw, 1.5rem);
}

.group-item {
    background: #fff;
    border: 3px solid #000;
    border-radius: 0;
    box-shadow: 8px 8px 0 #000;
    padding: clamp(1.5rem, 3vh, 2rem);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    display: flex;
    flex-direction: column;
    min-height: 200px;
}

.group-item:hover {
    transform: translateY(-4px);
    box-shadow: 8px 8px 0 #000;
}

.group-header {
    margin-top: clamp(0.75rem, 1.5vh, 1rem);
    margin-bottom: clamp(0.5rem, 1vh, 0.75rem);
}

.group-label {
    display: inline-block;
    padding: clamp(0.25rem, 0.5vh, 0.4rem) clamp(0.6rem, 1.2vw, 0.9rem);
    border-radius: 0;
    font-size: clamp(0.75rem, 1.8vw, 0.9rem);
    font-weight: 700;
    background: #000;
    color: #fff;
    letter-spacing: 0.05em;
}

.group-class-label {
    display: inline-block;
    padding: clamp(0.25rem, 0.5vh, 0.4rem) clamp(0.6rem, 1.2vw, 0.9rem);
    border-radius: 0;
    font-size: clamp(0.75rem, 1.8vw, 0.9rem);
    font-weight: 700;
    color: white;
    letter-spacing: 0.05em;
    margin-right: clamp(0.5rem, 1vw, 0.75rem);
    border: 2px solid #000;
}

/* クラスごとのラベル色（vivid） */
.group-item.class-mizuno .group-class-label {
    background: #0066FF;
}

.group-item.class-iguchi .group-class-label {
    background: #00C840;
    color: #000;
}

.group-item.class-takawo .group-class-label {
    background: #9B45F5;
}

.group-item.class-yao .group-class-label {
    background: #FF1C3A;
}

.group-item.class-yamashita .group-class-label {
    background: #FF7A00;
    color: #000;
}

.group-theme {
    font-size: clamp(1.1rem, 2.8vh, 1.5rem);
    font-weight: 700;
    color: #000;
    line-height: 1.5;
    margin-bottom: auto;
    flex-grow: 1;
    margin-top: 0;
}

.group-materials-button {
    padding: clamp(0.75rem, 1.5vh, 1rem) clamp(1.5rem, 3vw, 2rem);
    font-size: clamp(0.9rem, 2.2vw, 1.1rem);
    font-weight: 700;
    font-family: 'Noto Sans JP', sans-serif;
    color: white;
    background: #000;
    border: 3px solid #000;
    border-radius: 0;
    cursor: pointer;
    transition: all 0.2s ease;
    letter-spacing: 0.05em;
    box-shadow: 3px 3px 0 #000;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    width: 100%;
    margin-top: clamp(1rem, 2vh, 1.5rem);
    position: relative;
}

.group-materials-button i {
    margin-left: 0.4em;
    font-size: 0.9em;
    opacity: 0.9;
}

.group-materials-button:hover {
    transform: translateY(-3px);
    box-shadow: 6px 6px 0 #000;
}

.group-materials-button:active {
    transform: translateY(0);
    box-shadow: 1px 1px 0 #000;
}

/* クラスごとのカードシャドウ（neo-brutalist vivid） */
.group-item.class-mizuno {
    box-shadow: 8px 8px 0 #0066FF;
}

.group-item.class-mizuno:hover {
    box-shadow: 8px 8px 0 #0066FF;
}

.group-item.class-iguchi {
    box-shadow: 8px 8px 0 #00C840;
}

.group-item.class-iguchi:hover {
    box-shadow: 8px 8px 0 #00C840;
}

.group-item.class-takawo {
    box-shadow: 8px 8px 0 #9B45F5;
}

.group-item.class-takawo:hover {
    box-shadow: 8px 8px 0 #9B45F5;
}

.group-item.class-yao {
    box-shadow: 8px 8px 0 #FF1C3A;
}

.group-item.class-yao:hover {
    box-shadow: 8px 8px 0 #FF1C3A;
}

.group-item.class-yamashita {
    box-shadow: 8px 8px 0 #FF7A00;
}

.group-item.class-yamashita:hover {
    box-shadow: 8px 8px 0 #FF7A00;
}

/* クラスごとのボタンシャドウ */
.group-item.class-mizuno .group-materials-button {
    box-shadow: 3px 3px 0 #0066FF;
}

.group-item.class-mizuno .group-materials-button:hover {
    box-shadow: 6px 6px 0 #0066FF;
}

.group-item.class-iguchi .group-materials-button {
    box-shadow: 3px 3px 0 #00C840;
}

.group-item.class-iguchi .group-materials-button:hover {
    box-shadow: 6px 6px 0 #00C840;
}

.group-item.class-takawo .group-materials-button {
    box-shadow: 3px 3px 0 #9B45F5;
}

.group-item.class-takawo .group-materials-button:hover {
    box-shadow: 6px 6px 0 #9B45F5;
}

.group-item.class-yao .group-materials-button {
    box-shadow: 3px 3px 0 #FF1C3A;
}

.group-item.class-yao .group-materials-button:hover {
    box-shadow: 6px 6px 0 #FF1C3A;
}

.group-item.class-yamashita .group-materials-button {
    box-shadow: 3px 3px 0 #FF7A00;
}

.group-item.class-yamashita .group-materials-button:hover {
    box-shadow: 6px 6px 0 #FF7A00;
}

.group-youtube-container {
    width: 100%;
    margin-top: clamp(1rem, 2vh, 1.5rem);
    margin-bottom: clamp(1rem, 2vh, 1.5rem);
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    border: 3px solid #000;
    box-shadow: 8px 8px 0 #000;
}

.group-youtube-iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.group-image-container {
    width: 100%;
    margin-top: clamp(1rem, 2vh, 1.5rem);
    margin-bottom: clamp(1rem, 2vh, 1.5rem);
    border: 3px solid #000;
    box-shadow: 8px 8px 0 #000;
    overflow: hidden;
}

.group-image {
    width: 100%;
    height: auto;
    display: block;
    object-fit: cover;
    transition: opacity 0.1s ease;
    cursor: pointer;
}

.group-image-container {
    position: relative;
}

.group-image-container:hover .group-image {
    opacity: 0.9;
}

.list-container {
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0 clamp(1rem, 2vw, 2rem);
    padding-bottom: 2rem;
}

/* スクロール出現アニメーション */
.reveal-hidden {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.reveal-visible {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .groups-container {
        grid-template-columns: 1fr;
    }

    .group-item {
        padding: clamp(1rem, 2vh, 1.5rem);
    }

    .group-theme {
        font-size: clamp(0.95rem, 2.2vw, 1.2rem);
    }
}