/* ============================================================
   环境层：多层背景系统
   ============================================================ */

/* ---- 基础页面背景 ---- */
body {
    background-color: var(--bg-base);
    color: var(--foreground);
    font-family: var(--font-sans);
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ---- 背景层容器（固定定位，不干扰内容流） ---- */
.ambient-layer {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    overflow: hidden;
}

/* Layer 1: 基础径向渐变 — 从顶部中心向外发散 + 极光 */
.ambient-layer .layer-gradient {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 50% at 50% -20%, rgba(94,106,210,0.35), transparent),
        radial-gradient(ellipse 60% 40% at 20% 100%, rgba(124,58,237,0.25), transparent),
        radial-gradient(ellipse 60% 40% at 80% 100%, rgba(59,130,246,0.20), transparent),
        radial-gradient(ellipse 80% 60% at 50% 0%, #0a0a0f 0%, var(--bg-base) 50%, var(--bg-deep) 100%);
    animation: aurora-shift 15s ease-in-out infinite alternate;
}

/* Layer 2: 噪点纹理 — 防止色带 */
.ambient-layer .layer-noise {
    position: absolute;
    inset: 0;
    opacity: 0.015;
    background-image: url('/static/img/noise.svg');
    background-repeat: repeat;
    background-size: 200px 200px;
}

/* Layer 4: 技术网格 */
.ambient-layer .layer-grid {
    position: absolute;
    inset: 0;
    opacity: 0.02;
    background-image:
        linear-gradient(rgba(255,255,255,0.3) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.3) 1px, transparent 1px);
    background-size: 64px 64px;
    mask-image: radial-gradient(ellipse 70% 50% at 50% 30%, black 0%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse 70% 50% at 50% 30%, black 0%, transparent 70%);
}

/* ---- 动态效果画布层 ---- */
.effects-canvas-layer {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    overflow: hidden;
}

/* ============================================================
   内容层级隔离
   ============================================================ */

.content-layer {
    position: relative;
    z-index: 1;
}