:root {
    --bg-card: rgba(42, 45, 67, 0.85);
    --bg-header: linear-gradient(90deg, #7f5af0, #5f3dc4);
    --bg-header-hover: linear-gradient(90deg, #5f3dc4, #7f5af0);
    --bg-list: rgba(31, 33, 54, 0.9);
    --bg-item: #393c5a;
    --bg-item-hover: #585da6;
    --bg-item-active: #6e70d3;

    --accent: #7f5af0;
    --accent-alt: #5f3dc4;
    --accent-shadow: rgba(127, 90, 240, 0.8);

    --text-main: #e0e0ff;
    --text-muted: #c8caff;

    --border: #3c3f5a;
    --radius: 16px;
    --shadow: 0 6px 22px rgba(0, 0, 0, 0.5);
    --transition: all 0.3s ease;
    --font-main: system-ui, -apple-system, 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.container {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
    font-family: var(--font-main);
}

.categories-container {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.category {
    border-radius: var(--radius);
    background: var(--bg-card);
    box-shadow: 0 4px 18px rgba(127, 90, 240, 0.25);
    overflow: hidden;
    user-select: none;
    transition: var(--transition);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.06);
}

.category:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 26px rgba(127, 90, 240, 0.35);
}

.category-header {
    background: var(--bg-header);
    color: #fff;
    padding: 20px 36px;
    font-weight: 700;
    font-size: 1.25rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-radius: var(--radius) var(--radius) 0 0;
    transition: var(--transition);
    user-select: none;
    letter-spacing: 0.02em;
    box-shadow: inset 0 -1px 0 rgba(255, 255, 255, 0.05);
}

.category-header:hover,
.category-header:focus {
    background: var(--bg-header-hover);
    outline: none;
    box-shadow: 0 0 20px var(--accent-shadow);
}

.category-header .count {
    background: #524fd9;
    padding: 6px 16px;
    border-radius: 30px;
    font-weight: 700;
    font-size: 1.05rem;
    color: #d1d1ff;
    min-width: 38px;
    text-align: center;
    box-shadow: 0 0 10px rgba(82, 79, 217, 0.6);
    transition: var(--transition);
}

.category-header:hover .count {
    background: #6e6aff;
    box-shadow: 0 0 14px rgba(127, 90, 240, 0.8);
}

.category-list {
    max-height: 0;
    overflow: hidden;
    background: var(--bg-list);
    border-top: 1px solid var(--border);
    font-size: 1rem;
    user-select: none;
    transition: max-height 0.4s ease;
}

.category.open .category-list {
    max-height: 1200px;
    transition: max-height 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.category-list ul {
    list-style: none;
    margin: 0;
    padding: 18px 26px;
    max-height: 400px;
    overflow-y: auto;
}

.category-list li {
    padding: 14px 20px;
    margin-bottom: 12px;
    border-radius: 12px;
    background: var(--bg-item);
    cursor: pointer;
    font-weight: 600;
    color: var(--text-muted);
    box-shadow: 0 2px 10px rgba(83, 89, 139, 0.4);
    transition: var(--transition);
    user-select: none;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    position: relative;
}

.category-list li:hover,
.category-list li:focus {
    background: var(--bg-item-hover);
    outline: none;
    box-shadow: 0 0 14px var(--accent-shadow);
    color: var(--text-main);
    transform: translateY(-1px);
}

.category-list li[aria-expanded="true"] {
    background: var(--bg-item-active);
    font-weight: 700;
    white-space: normal;
    cursor: default;
    color: #fff;
    box-shadow: 0 0 22px var(--accent-shadow);
}

.category-list li[aria-expanded="true"] .info-box {
    display: block;
}

.category-list {
    scrollbar-width: thin;
    scrollbar-color: var(--accent) var(--bg-list);
}

.category-list::-webkit-scrollbar {
    width: 10px;
}

.category-list::-webkit-scrollbar-track {
    background: var(--bg-list);
    border-radius: 10px;
}

.category-list::-webkit-scrollbar-thumb {
    background-color: var(--accent);
    border-radius: 10px;
    border: 2px solid var(--bg-list);
}

@keyframes fadeInCategory {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.category {
    animation: fadeInCategory 0.4s ease both;
}

@media (max-width: 600px) {
    .category-header {
        font-size: 1.1rem;
        padding: 16px 22px;
    }

    .category-list li {
        font-size: 0.95rem;
        padding: 12px 16px;
    }
}