:root{--bg:#f7f9fc;--surface:#fff;--text:#172033;--muted:#64748b;--line:#e5e7eb;--primary:#2563eb;--primary-dark:#1d4ed8;--soft:#eef4ff;--danger:#dc2626;--radius:18px;--shadow:0 16px 40px rgba(15,23,42,.08);--max:1160px}*{box-sizing:border-box}body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;background:var(--bg);color:var(--text);line-height:1.65}a{color:var(--primary);text-decoration:none}a:hover{text-decoration:underline}.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.94);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:14px max(20px,calc((100vw - var(--max))/2));gap:20px}.logo{display:flex;align-items:center;gap:10px;color:var(--text);font-weight:850;font-size:1.08rem}.logo:hover{text-decoration:none}.logo-mark{display:inline-flex;align-items:center;justify-content:center;background:var(--primary);color:#fff;border-radius:10px;width:42px;height:34px;font-size:.82rem;letter-spacing:.04em}.site-nav{display:flex;align-items:center;gap:18px;font-weight:650}.site-nav a{color:#253047}.menu-toggle{display:none;border:1px solid var(--line);background:#fff;border-radius:10px;padding:8px 12px;font-size:1.2rem}.nav-dropdown{position:relative}.dropdown-menu{display:none;position:absolute;top:100%;left:0;background:#fff;border:1px solid var(--line);box-shadow:var(--shadow);border-radius:14px;min-width:210px;padding:8px}.dropdown-menu.wide{min-width:260px}.dropdown-menu a{display:block;padding:8px 10px}.nav-dropdown:hover .dropdown-menu{display:block}.hero{max-width:var(--max);margin:0 auto;padding:64px 20px 34px;display:grid;grid-template-columns:1.12fr .88fr;gap:32px;align-items:center}.hero-card{background:linear-gradient(135deg,#eef4ff,#fff);border:1px solid #dbeafe;border-radius:28px;padding:34px;box-shadow:var(--shadow)}.kicker{font-weight:850;color:var(--primary);text-transform:uppercase;font-size:.82rem;letter-spacing:.08em}.hero h1,.page-hero h1{font-size:clamp(2.15rem,5vw,4rem);line-height:1.05;margin:.2em 0}.hero p,.page-hero p{font-size:1.1rem;color:var(--muted)}.cta-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:22px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;background:var(--primary);color:#fff;border:none;border-radius:999px;padding:12px 20px;font-weight:800;cursor:pointer;box-shadow:0 10px 22px rgba(37,99,235,.18)}.btn:hover{background:var(--primary-dark);text-decoration:none}.btn.secondary{background:#fff;color:var(--primary);border:1px solid #bfdbfe;box-shadow:none}.btn.danger{background:var(--danger)}.btn.small{padding:8px 14px;font-size:.9rem}.btn:disabled{opacity:.55;cursor:not-allowed}.section{max-width:var(--max);margin:0 auto;padding:34px 20px}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.grid.two{grid-template-columns:repeat(2,1fr)}.grid.four{grid-template-columns:repeat(4,1fr)}.card,.tool-panel,.article-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:24px;box-shadow:0 8px 24px rgba(15,23,42,.05)}.card h3,.article-card h3{margin-top:0}.tool-card{display:flex;flex-direction:column;gap:12px;color:var(--text)}.tool-card:hover{text-decoration:none;border-color:#bfdbfe}.tool-icon{width:46px;height:46px;display:flex;align-items:center;justify-content:center;border-radius:14px;background:var(--soft);font-size:1.5rem}.page-hero{max-width:var(--max);margin:0 auto;padding:50px 20px 20px}.trust-row{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-top:22px}.trust-item{background:#fff;border:1px solid var(--line);border-radius:16px;padding:14px;font-weight:700}.tool-layout{max-width:var(--max);margin:0 auto;padding:28px 20px;display:grid;grid-template-columns:1fr 320px;gap:24px;align-items:start}.tool-panel h2{margin-top:0}.drop-zone{border:2px dashed #bcd3ff;background:#f8fbff;border-radius:20px;padding:28px;text-align:center;transition:.2s;cursor:pointer}.drop-zone.dragover{background:#eef6ff;border-color:var(--primary)}.drop-zone input{display:none}.file-list{margin-top:16px;display:flex;flex-direction:column;gap:8px}.file-item{display:flex;align-items:center;justify-content:space-between;background:#f8fafc;border:1px solid var(--line);border-radius:12px;padding:10px 12px;gap:10px;word-break:break-word}.form-row{display:grid;gap:8px;margin:16px 0}.form-row label{font-weight:800}.form-row input,.form-row select,.form-row textarea{width:100%;border:1px solid var(--line);border-radius:12px;padding:12px;font:inherit;background:#fff}.form-inline{display:grid;grid-template-columns:1fr 1fr;gap:14px}.hint{color:var(--muted);font-size:.95rem}.status{margin-top:14px;padding:12px;border-radius:12px;background:#f8fafc;border:1px solid var(--line);display:none}.status.show{display:block}.status.error{background:#fff1f2;border-color:#fecdd3;color:#9f1239}.status.success{background:#f0fdf4;border-color:#bbf7d0;color:#166534}.ad-box{border:1px dashed #cbd5e1;border-radius:16px;min-height:160px;display:none;align-items:center;justify-content:center;color:#94a3b8;background:#fafafa;font-size:.9rem;text-align:center;padding:16px;margin:18px 0}.sidebar{display:grid;gap:16px}.sidebar .ad-box{margin:0}.mini-list{padding-left:18px}.article{max-width:860px;margin:0 auto;padding:34px 20px}.article h1{font-size:clamp(2rem,5vw,3.25rem);line-height:1.1}.article p,.article li{color:#334155}.article-meta{color:var(--muted);font-weight:700}.article-content h2{margin-top:36px}.related-tools{display:flex;flex-wrap:wrap;gap:10px;margin:18px 0}.preview-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(120px,1fr));gap:12px;margin-top:16px}.preview-page{background:#fff;border:1px solid var(--line);border-radius:14px;padding:8px;text-align:center}.preview-page canvas,.preview-page img{width:100%;height:auto;border-radius:8px;background:#f8fafc}.preview-page span{display:block;font-size:.85rem;color:var(--muted);margin-top:4px}.site-footer{max-width:var(--max);margin:40px auto 0;padding:30px 20px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:20px;color:var(--muted)}.site-footer nav{display:flex;flex-wrap:wrap;gap:14px}.site-footer a{color:#475569}.notice{background:#fffbeb;border:1px solid #fde68a;color:#92400e;padding:14px;border-radius:14px}.success-box{background:#ecfdf5;border:1px solid #a7f3d0;color:#065f46;padding:16px;border-radius:16px}.table{width:100%;border-collapse:collapse;background:#fff;border-radius:14px;overflow:hidden;border:1px solid var(--line)}.table th,.table td{padding:12px;border-bottom:1px solid var(--line);text-align:left}.table tr:last-child td{border-bottom:0}.skip{position:absolute;left:-9999px}.skip:focus{left:20px;top:20px;background:#fff;padding:10px;z-index:1000}@media(max-width:900px){.hero{grid-template-columns:1fr;padding-top:34px}.grid,.grid.two,.grid.four,.trust-row,.tool-layout,.form-inline{grid-template-columns:1fr}.site-nav{display:none;position:absolute;left:12px;right:12px;top:66px;background:#fff;border:1px solid var(--line);box-shadow:var(--shadow);border-radius:18px;padding:14px;flex-direction:column;align-items:flex-start}.site-nav.open{display:flex}.menu-toggle{display:block}.dropdown-menu{position:static;display:block;border:none;box-shadow:none;padding:0}.site-footer{flex-direction:column}.hero-card{padding:24px}}

/* PDF page preview selection and modal */
.preview-help{grid-column:1/-1;margin:0 0 4px}.preview-limit-note{grid-column:1/-1;margin:4px 0 0}.preview-page.interactive{position:relative;cursor:pointer;transition:border-color .16s ease,box-shadow .16s ease,transform .16s ease}.preview-page.interactive:hover{border-color:#93c5fd;box-shadow:0 10px 24px rgba(37,99,235,.10);transform:translateY(-1px)}.preview-page.selected{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.16),0 10px 24px rgba(37,99,235,.12)}.preview-page.selected::after{content:'✓';position:absolute;top:8px;right:8px;width:24px;height:24px;border-radius:999px;background:var(--primary);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:900;font-size:.86rem}.preview-actions{display:flex;align-items:center;justify-content:space-between;gap:8px;margin-top:8px}.preview-actions .btn.small{padding:6px 10px;font-size:.78rem}.select-label{color:var(--muted);font-weight:800}.preview-modal{position:fixed;inset:0;z-index:1000;display:none}.preview-modal.open{display:block}.preview-modal-backdrop{position:absolute;inset:0;background:rgba(15,23,42,.72);backdrop-filter:blur(4px)}.preview-modal-dialog{position:relative;z-index:1;max-width:min(1040px,92vw);max-height:92vh;margin:4vh auto;background:#fff;border-radius:20px;box-shadow:0 28px 80px rgba(2,6,23,.32);display:flex;flex-direction:column;overflow:hidden}.preview-modal-header{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:14px 16px;border-bottom:1px solid var(--line)}.preview-modal-body{padding:16px;overflow:auto;background:#f8fafc;text-align:center}.preview-modal-body canvas{max-width:100%;height:auto;background:#fff;border:1px solid var(--line);border-radius:10px;box-shadow:0 12px 36px rgba(15,23,42,.12)}@media(max-width:700px){.preview-actions{flex-direction:column;align-items:stretch}.preview-actions .btn.small{width:100%}.preview-modal-dialog{margin:2vh auto;max-height:96vh}}


/* Central ad loader styles */
.ad-box.ad-loaded{border-style:solid;background:#fff;color:var(--muted);display:block;min-height:180px;padding:12px}.ad-label{font-size:.78rem;text-transform:uppercase;letter-spacing:.08em;color:#94a3b8;text-align:center;margin-bottom:8px}.ad-box.ad-disabled{border-style:dashed;background:#fafafa;color:#94a3b8}

.lang-link{font-weight:700;border:1px solid var(--border);border-radius:999px;padding:.45rem .75rem;background:#fff}
html[lang="zh-CN"] body{font-family:Inter,-apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',Arial,sans-serif;}