:root{--icon-blue:#2563eb;--icon-violet:#7c3aed;--icon-green:#059669;--icon-orange:#ea580c}
.app-icon{width:48px;height:48px;border-radius:14px;display:inline-grid;place-items:center;color:#fff;font-size:24px;line-height:1;background:linear-gradient(135deg,var(--icon-blue),#38bdf8);box-shadow:0 10px 24px rgba(37,99,235,.2)}
.app-icon::before{font-family:"Segoe UI Emoji","Apple Color Emoji",sans-serif}
/* 智能工具箱：每个工具一个独立图标字形（此前 6 个 PDF 工具共用一个蓝色 PDF 方块，辨识度低） */
.icon-merge::before{content:"📑"}
.icon-split::before{content:"✂️"}
.icon-organize::before{content:"🔀"}
.icon-remove::before{content:"🗑️"}
.icon-rotate::before{content:"🔄"}
.icon-pagenumber::before{content:"🔢"}
.icon-imagepdf::before{content:"🖼️"}
.icon-compress::before{content:"🗜️"}
.icon-ai::before{content:"✨"}
.icon-video::before{content:"🎬"}
.icon-watermark::before{content:"💧"}
.icon-palette::before{content:"🎨"}
.icon-lock::before{content:"🔐"}
/* 兼容旧类名 */
.icon-pdf::before{content:"📄"}
.icon-image::before{content:"🖼️"}
/* 每个图标的品牌渐变（补齐早前只有 3 组配色的缺口） */
.icon-pdf,.icon-merge,.icon-split{background:linear-gradient(135deg,#ef4444,#f97316)}
.icon-organize,.icon-remove,.icon-rotate,.icon-pagenumber{background:linear-gradient(135deg,#4f46e5,#818cf8)}
.icon-image,.icon-imagepdf{background:linear-gradient(135deg,#0891b2,#22d3ee)}
.icon-compress{background:linear-gradient(135deg,#059669,#2dd4bf)}
.icon-ai{background:linear-gradient(135deg,#7c3aed,#ec4899)}
.icon-video{background:linear-gradient(135deg,#db2777,#fb7185)}
.icon-watermark{background:linear-gradient(135deg,#0284c7,#38bdf8)}
.icon-palette{background:linear-gradient(135deg,#f59e0b,#fbbf24)}
.icon-lock{background:linear-gradient(135deg,#334155,#64748b)}