*{margin:0;padding:0;box-sizing:border-box}
:root{--primary:#4f46e5;--primary-light:#818cf8;--bg:#f8fafc;--card:#fff;--text:#1e293b;--text-light:#64748b;--border:#e2e8f0;--radius:12px;--shadow:0 1px 3px rgba(0,0,0,.08),0 1px 2px rgba(0,0,0,.06)}
body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Noto Sans SC',sans-serif;background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh;display:flex;flex-direction:column}
a{color:inherit;text-decoration:none}
.container{max-width:1100px;margin:0 auto;padding:0 20px;width:100%}

/* Header */
header{background:linear-gradient(135deg,var(--primary),#7c3aed);color:#fff;padding:48px 0 40px;text-align:center}
header h1{font-size:2rem;font-weight:700;margin-bottom:8px}
.subtitle{opacity:.85;font-size:1.05rem}

/* Tools Grid */
.tools-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:24px;padding:40px 0 60px}
.tool-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:32px 24px;text-align:center;transition:all .2s;position:relative;box-shadow:var(--shadow)}
.tool-card:hover{transform:translateY(-4px);box-shadow:0 12px 24px rgba(0,0,0,.1);border-color:var(--primary-light)}
.tool-icon{font-size:2.5rem;margin-bottom:16px;font-weight:700;color:var(--primary)}
.tool-card h3{font-size:1.15rem;margin-bottom:8px}
.tool-card p{color:var(--text-light);font-size:.92rem}
.tag{display:inline-block;background:var(--primary);color:#fff;font-size:.72rem;padding:3px 10px;border-radius:20px;margin-top:12px;font-weight:500}

/* Footer */
footer{background:#1e293b;color:#94a3b8;padding:24px 0;text-align:center;font-size:.85rem;margin-top:auto}

/* Tool Page Layout */
.tool-page{padding:40px 0 60px}
.tool-page .back{display:inline-flex;align-items:center;gap:6px;color:var(--primary);font-size:.92rem;margin-bottom:24px}
.tool-page .back:hover{text-decoration:underline}
.tool-page h2{font-size:1.6rem;margin-bottom:8px}
.tool-page .desc{color:var(--text-light);margin-bottom:28px}
.tool-page textarea,.tool-page input[type=text],.tool-page input[type=number],.tool-page select{width:100%;padding:12px 16px;border:1px solid var(--border);border-radius:8px;font-size:.95rem;font-family:inherit;resize:vertical;transition:border .2s}
.tool-page textarea:focus,.tool-page input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(79,70,229,.1)}
.tool-page textarea{min-height:160px;font-family:'Fira Code',Consolas,monospace}
.tool-page .btn{display:inline-flex;align-items:center;gap:6px;background:var(--primary);color:#fff;border:none;padding:10px 24px;border-radius:8px;font-size:.95rem;cursor:pointer;transition:background .2s;font-weight:500}
.tool-page .btn:hover{background:#4338ca}
.tool-page .btn-outline{background:transparent;color:var(--primary);border:1.5px solid var(--primary)}
.tool-page .btn-outline:hover{background:rgba(79,70,229,.06)}
.btn-group{display:flex;gap:10px;flex-wrap:wrap;margin:16px 0}
.result-box{background:#f1f5f9;border:1px solid var(--border);border-radius:8px;padding:16px;margin-top:16px;white-space:pre-wrap;word-break:break-all;font-family:'Fira Code',Consolas,monospace;font-size:.9rem;min-height:60px;position:relative}
.result-box .copy-btn{position:absolute;top:8px;right:8px;background:var(--primary);color:#fff;border:none;padding:4px 12px;border-radius:6px;font-size:.78rem;cursor:pointer}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.two-col>div{display:flex;flex-direction:column}
.two-col label{font-weight:600;margin-bottom:6px;font-size:.9rem}
.row{display:flex;gap:12px;align-items:center;margin-bottom:12px;flex-wrap:wrap}
.row label{font-weight:600;white-space:nowrap;font-size:.9rem;min-width:70px}
.stats{display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:12px;margin-top:16px}
.stat-card{background:var(--card);border:1px solid var(--border);border-radius:8px;padding:16px;text-align:center}
.stat-card .num{font-size:1.8rem;font-weight:700;color:var(--primary)}
.stat-card .label{font-size:.82rem;color:var(--text-light);margin-top:4px}

/* QR code */
#qr-output{display:flex;justify-content:center;margin:20px 0}
#qr-output canvas,#qr-output img{border-radius:8px}

/* Markdown preview */
.preview-area{background:var(--card);border:1px solid var(--border);border-radius:8px;padding:20px;min-height:200px;font-size:.95rem;line-height:1.8}
.preview-area h1,.preview-area h2,.preview-area h3{margin:16px 0 8px;font-weight:700}
.preview-area h1{font-size:1.6rem;border-bottom:1px solid var(--border);padding-bottom:6px}
.preview-area h2{font-size:1.3rem}
.preview-area h3{font-size:1.1rem}
.preview-area p{margin:8px 0}
.preview-area code{background:#f1f5f9;padding:2px 6px;border-radius:4px;font-size:.88em}
.preview-area pre{background:#1e293b;color:#e2e8f0;padding:16px;border-radius:8px;overflow-x:auto;margin:12px 0}
.preview-area pre code{background:transparent;color:inherit;padding:0}
.preview-area blockquote{border-left:4px solid var(--primary);padding:8px 16px;margin:12px 0;color:var(--text-light);background:#f8fafc;border-radius:0 8px 8px 0}
.preview-area ul,.preview-area ol{padding-left:24px;margin:8px 0}
.preview-area li{margin:4px 0}
.preview-area a{color:var(--primary);text-decoration:underline}
.preview-area img{max-width:100%;border-radius:8px}
.preview-area hr{border:none;border-top:1px solid var(--border);margin:16px 0}
.preview-area table{border-collapse:collapse;width:100%;margin:12px 0}
.preview-area th,.preview-area td{border:1px solid var(--border);padding:8px 12px;text-align:left}
.preview-area th{background:#f1f5f9;font-weight:600}

/* Responsive */
@media(max-width:640px){
  header{padding:32px 0 28px}
  header h1{font-size:1.5rem}
  .tools-grid{grid-template-columns:1fr;gap:16px;padding:24px 0 40px}
  .two-col{grid-template-columns:1fr}
  .tool-card{padding:24px 20px}
}