:root {
    /* 圆盘：随视口与较小边缩放，避免超出左侧窄栏 */
    --disk-size: clamp(6.75rem, min(20vmin, 15vw), 14rem);
    --bg-speed: 0.8s;
    /* 本页作为独立版块时，高度为视口高度的 70% */
    --ai-hub-section-height: 100vh;
    --ai-hub-left-gap: 15%;
}
/* 版块容器：高度 = 窗口高度的 70%，后续可在其上/下接其他 section */
.hub-section {
    position: relative;
    width: 100%;
    height: var(--ai-hub-section-height);
    min-height: var(--ai-hub-section-height);
    overflow: hidden;
    background-image: url('../img/yellow.svg');
    background-size:30rem;
}

/* 背景层：仅占右侧 70%，左侧 30% 留白 */
.bg-layer {
    position: absolute;
    top: 10%;
    bottom: 0;
    left: var(--ai-hub-left-gap);
    right: 0;
    width: auto;
    height: auto;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    filter: brightness(1.0); 
    transition: background-image var(--bg-speed) cubic-bezier(0.4, 0, 0.2, 1), 
                transform 1.2s cubic-bezier(0.1, 0, 0.2, 1);
    z-index: 0;
    will-change: background-image, transform;
}

/* 内容区（落在左侧留白区内） */
.content-area {
    position: absolute;
    top: clamp(20%, 12vh, 18%);
    left: clamp(0.75rem, 3.5vw, 3rem);
    max-width: calc(var(--ai-hub-left-gap) - clamp(1.5rem, 5vw, 4rem));
    z-index: 10;
    pointer-events: none;
}

.content-title {
    font-size: clamp(1.85rem, 3.5vw + 1.1rem, 4.25rem);
    font-weight: 900;
    line-height: 1.05;
    transition: color 0.5s ease;
    text-transform: uppercase;
    text-shadow: 0 clamp(2px, 0.4vw, 5px) clamp(10px, 2vw, 20px) rgba(0, 0, 0, 0.45);
}

.content-desc {
    margin-top: clamp(0.35rem, 1.2vh, 0.85rem);
    font-size: clamp(1.8rem, 1.1vw + 0.55rem, 1.125rem);
    line-height: 1.55;
    color: rgba(255, 255, 255, 0.9);
    opacity: 0;
    transform: translateY(clamp(8px, 1.2vh, 15px));
    transition: all 0.6s cubic-bezier(0.2, 0.8, 0.2, 1);
    text-shadow: 0 2px clamp(6px, 1vw, 10px) rgba(0, 0, 0, 0.75);
}

.active-text .content-desc {
    opacity: 1;
    transform: translateY(0);
}

/* 圆盘锚点（相对于版块左下角；不大于左侧留白宽度） */
.disk-anchor {
    position: absolute;
    bottom: clamp(0.6rem, 2.5vmin, 3rem);
    left: clamp(0.6rem, 2.5vmin, 3rem);
    width: min(var(--disk-size), calc(var(--ai-hub-left-gap) - clamp(0.75rem, 3vw, 2rem)));
    aspect-ratio: 1;
    height: auto;
    perspective: 1000px;
    z-index: 100;
}

/* 恢复旋转轨道特效 */
.disk-orbit {
    position: absolute;
    top: -8.33%;
    left: -8.33%;
    right: -8.33%;
    bottom: -8.33%;
    border: 1px solid rgba(252, 5, 5, 0.1);
    border-top: 1px solid rgba(240, 8, 8, 0.945);
    border-radius: 50%;
    animation: orbit-rotate 10s linear infinite;
    pointer-events: none;
}

@keyframes orbit-rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.disk {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.sector {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    cursor: pointer;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255,255,255,0.1);
    /* 极致平滑过渡 */
    transition: all 0.4s cubic-bezier(0.2, 0.8, 0.2, 1);
    will-change: transform, background-color;
}

/* 四等分路径 */
.s1 { clip-path: polygon(50% 50%, 50% 0%, 100% 0%, 100% 50%); }
.s2 { clip-path: polygon(50% 50%, 100% 50%, 100% 100%, 50% 100%); }
.s3 { clip-path: polygon(50% 50%, 50% 100%, 0% 100%, 0% 50%); }
.s4 { clip-path: polygon(50% 50%, 0% 50%, 0% 0%, 50% 0%); }

/* 选中效果：小幅度凸起 (20px) & 更加流畅的高亮 */
.sector.is-active, .sector:hover {
    z-index: 10;
    transform: scale(1.05) translateZ(clamp(10px, 2.5vmin, 22px));
    background-color: var(--active-color) !important;
    filter: brightness(1.1);
    border-color: rgba(255,255,255,0.4);
    box-shadow: 0 0 clamp(14px, 3.5vmin, 32px) var(--active-color);
}

.disk-center {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    width: 28%; height: 28%;
    background: #000;
    border-radius: 50%;
    z-index: 20;
    border: 1px solid rgba(255,255,255,0.2);
    pointer-events: none;
}