/* ============================================================
   cover.css - GuitarMasta 2.0 封面图系统
   路径：/css/cover.css
   包含：四层封面结构、光点闪烁动画（仅opacity，2-4秒随机）
         产品主体光晕、三级降级机制、移动端响应式
   ============================================================ */

/* ============ 1. 封面容器基础 ============ */
.cover-container {
    position: relative;
    width: 100%;
    aspect-ratio: 16 / 9;
    border-radius: var(--radius-card);
    overflow: hidden;
    background: var(--c-secondary-dark);
    isolation: isolate;
}

/* 文章详情页横幅比例 */
.cover-container.cover-banner {
    aspect-ratio: 2 / 1;
}

/* 聚合页卡片比例 */
.cover-container.cover-card {
    aspect-ratio: 16 / 9;
}

/* ============ 2. 四层封面结构 ============ */

/* 第一层：背景色（由 SVG 提供，容器保留作为降级背景） */
.cover-layer-bg {
    position: absolute;
    inset: 0;
    z-index: 1;
    background: linear-gradient(135deg, var(--c-secondary-dark), var(--c-secondary), var(--c-secondary-light));
}

/* 第二层：衬托背景物品（SVG 内绘制，此处为容器占位） */
.cover-layer-props {
    position: absolute;
    inset: 0;
    z-index: 2;
    pointer-events: none;
}

/* 第三层：产品主体 + 柔光边缘 */
.cover-layer-product {
    position: absolute;
    inset: 0;
    z-index: 3;
    display: flex;
    align-items: center;
    justify-content: center;
    pointer-events: none;
}

.cover-layer-product img,
.cover-layer-product svg {
    max-width: 60%;
    max-height: 60%;
    object-fit: contain;
    filter: drop-shadow(0 0 30px rgba(255, 255, 255, 0.25))
            drop-shadow(0 0 60px rgba(255, 255, 255, 0.12));
    animation: productGlow 3.5s ease-in-out infinite alternate;
}

@keyframes productGlow {
    0% {
        filter: drop-shadow(0 0 20px rgba(255, 255, 255, 0.2))
                drop-shadow(0 0 40px rgba(255, 255, 255, 0.1));
    }
    100% {
        filter: drop-shadow(0 0 35px rgba(255, 255, 255, 0.3))
                drop-shadow(0 0 70px rgba(255, 255, 255, 0.15));
    }
}

/* 第四层：动态闪烁光点 */
.cover-layer-dots {
    position: absolute;
    inset: 0;
    z-index: 4;
    pointer-events: none;
}

/* 光点基础样式 */
.cover-dot {
    position: absolute;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.8);
    box-shadow: 0 0 8px rgba(255, 255, 255, 0.4);
    animation: dotTwinkle 3s ease-in-out infinite;
}

/* 光点尺寸变体 */
.cover-dot.dot-sm {
    width: 4px;
    height: 4px;
    box-shadow: 0 0 5px rgba(255, 255, 255, 0.3);
}

.cover-dot.dot-lg {
    width: 8px;
    height: 8px;
    box-shadow: 0 0 12px rgba(255, 255, 255, 0.5);
}

/* 光点颜色变体 */
.cover-dot.dot-warm {
    background: rgba(224, 122, 95, 0.85);
    box-shadow: 0 0 10px rgba(224, 122, 95, 0.5);
}

.cover-dot.dot-gold {
    background: rgba(212, 162, 76, 0.85);
    box-shadow: 0 0 10px rgba(212, 162, 76, 0.5);
}

.cover-dot.dot-blue {
    background: rgba(45, 95, 124, 0.85);
    box-shadow: 0 0 10px rgba(45, 95, 124, 0.5);
}

/* 光点闪烁动画 - 使用独立CSS变量控制节奏 */
@keyframes dotTwinkle {
    0%, 100% {
        opacity: 0.3;
    }
    25% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
    75% {
        opacity: 0.9;
    }
}

/* 不同节奏的光点（通过内联 style 或 CSS 类控制动画时长） */
.cover-dot.dot-speed-1 { animation-duration: 2.0s; }
.cover-dot.dot-speed-2 { animation-duration: 2.4s; }
.cover-dot.dot-speed-3 { animation-duration: 2.8s; }
.cover-dot.dot-speed-4 { animation-duration: 3.2s; }
.cover-dot.dot-speed-5 { animation-duration: 3.6s; }
.cover-dot.dot-speed-6 { animation-duration: 4.0s; }

.cover-dot.dot-delay-1 { animation-delay: 0.2s; }
.cover-dot.dot-delay-2 { animation-delay: 0.5s; }
.cover-dot.dot-delay-3 { animation-delay: 0.8s; }
.cover-dot.dot-delay-4 { animation-delay: 1.2s; }
.cover-dot.dot-delay-5 { animation-delay: 1.6s; }
.cover-dot.dot-delay-6 { animation-delay: 2.0s; }

/* ============ 3. 标题文字覆盖层 ============ */
.cover-title-overlay {
    position: absolute;
    left: var(--sp-5);
    right: var(--sp-5);
    bottom: var(--sp-5);
    z-index: 5;
    pointer-events: none;
    text-align: left;
}

.cover-title-overlay .cover-title-text {
    font-family: var(--font-serif);
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    font-weight: 700;
    color: #fff;
    line-height: 1.3;
    margin: 0;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
}

.cover-title-overlay .cover-subtitle {
    font-size: var(--fs-small);
    color: rgba(255, 255, 255, 0.8);
    margin: var(--sp-2) 0 0;
}

/* ============ 4. 三级降级机制 ============ */

/* 降级一级：外部图片 → SVG */
.cover-container img.cover-external,
.cover-container svg.cover-svg {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 0;
    border-radius: 0;
}

/* 降级二级：SVG → 纯色背景 + 标题 */
.cover-container.cover-fallback-mode {
    background: linear-gradient(135deg, var(--c-secondary-dark), var(--c-secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--sp-5);
}

.cover-container.cover-fallback-mode .cover-fallback-content {
    color: #fff;
    z-index: 10;
}

.cover-container.cover-fallback-mode .cover-fallback-title {
    font-family: var(--font-serif);
    font-size: clamp(1.25rem, 2.5vw, 1.75rem);
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--sp-2);
}

.cover-container.cover-fallback-mode .cover-fallback-sub {
    font-size: var(--fs-small);
    color: rgba(255, 255, 255, 0.75);
}

/* 降级时隐藏光点和其他装饰层 */
.cover-container.cover-fallback-mode .cover-layer-dots,
.cover-container.cover-fallback-mode .cover-layer-product,
.cover-container.cover-fallback-mode .cover-layer-props {
    display: none;
}

/* ============ 5. 光点位置类（供JS动态生成使用） ============ */
/* 预设位置便于快速生成，实际使用时由JS随机计算 */
.dot-pos-1 { top: 12%; left: 8%; }
.dot-pos-2 { top: 18%; left: 22%; }
.dot-pos-3 { top: 8%; left: 35%; }
.dot-pos-4 { top: 25%; left: 50%; }
.dot-pos-5 { top: 10%; left: 65%; }
.dot-pos-6 { top: 22%; left: 78%; }
.dot-pos-7 { top: 8%; left: 90%; }
.dot-pos-8 { top: 35%; left: 12%; }
.dot-pos-9 { top: 40%; left: 30%; }
.dot-pos-10 { top: 32%; left: 55%; }
.dot-pos-11 { top: 38%; left: 72%; }
.dot-pos-12 { top: 35%; left: 88%; }
.dot-pos-13 { top: 55%; left: 6%; }
.dot-pos-14 { top: 60%; left: 20%; }
.dot-pos-15 { top: 52%; left: 40%; }
.dot-pos-16 { top: 58%; left: 62%; }
.dot-pos-17 { top: 55%; left: 80%; }
.dot-pos-18 { top: 60%; left: 94%; }
.dot-pos-19 { top: 75%; left: 10%; }
.dot-pos-20 { top: 80%; left: 28%; }
.dot-pos-21 { top: 72%; left: 48%; }
.dot-pos-22 { top: 78%; left: 68%; }
.dot-pos-23 { top: 75%; left: 85%; }
.dot-pos-24 { top: 88%; left: 15%; }
.dot-pos-25 { top: 90%; left: 38%; }
.dot-pos-26 { top: 85%; left: 58%; }
.dot-pos-27 { top: 90%; left: 75%; }

/* ============ 6. 移动端响应式 ============ */
@media screen and (max-width: 768px) {
    .cover-container.cover-banner {
        aspect-ratio: 16 / 9;
    }

    /* 移动端光点数量减半：隐藏奇数位置的光点 */
    .cover-dot.dot-pos-1,
    .cover-dot.dot-pos-3,
    .cover-dot.dot-pos-5,
    .cover-dot.dot-pos-7,
    .cover-dot.dot-pos-9,
    .cover-dot.dot-pos-11,
    .cover-dot.dot-pos-13,
    .cover-dot.dot-pos-15,
    .cover-dot.dot-pos-17,
    .cover-dot.dot-pos-19,
    .cover-dot.dot-pos-21,
    .cover-dot.dot-pos-23,
    .cover-dot.dot-pos-25,
    .cover-dot.dot-pos-27 {
        display: none;
    }

    /* 移动端光点尺寸略小 */
    .cover-dot {
        width: 4px;
        height: 4px;
    }

    .cover-dot.dot-lg {
        width: 6px;
        height: 6px;
    }

    /* 产品光晕稍弱，节省渲染 */
    .cover-layer-product img,
    .cover-layer-product svg {
        filter: drop-shadow(0 0 15px rgba(255, 255, 255, 0.2))
                drop-shadow(0 0 30px rgba(255, 255, 255, 0.1));
    }

    .cover-title-overlay {
        left: var(--sp-3);
        right: var(--sp-3);
        bottom: var(--sp-3);
    }

    .cover-title-overlay .cover-title-text {
        font-size: 1.0625rem;
    }
}

@media screen and (max-width: 480px) {
    .cover-container.cover-card {
        aspect-ratio: 16 / 10;
    }

    .cover-title-overlay .cover-subtitle {
        display: none;
    }

    /* 光点动画时长略加快，减少资源消耗 */
    .cover-dot.dot-speed-1 { animation-duration: 1.6s; }
    .cover-dot.dot-speed-2 { animation-duration: 1.8s; }
    .cover-dot.dot-speed-3 { animation-duration: 2.0s; }
    .cover-dot.dot-speed-4 { animation-duration: 2.2s; }
    .cover-dot.dot-speed-5 { animation-duration: 2.4s; }
    .cover-dot.dot-speed-6 { animation-duration: 2.6s; }
}

/* ============ 7. 减少动态偏好 ============ */
@media (prefers-reduced-motion: reduce) {
    .cover-dot {
        animation: none;
        opacity: 0.7;
    }

    .cover-layer-product img,
    .cover-layer-product svg {
        animation: none;
    }

    .cover-container {
        transition: none;
    }
}