:root{--primary:#4361ee;--primary-dark:#3a56d4;--secondary:#7209b7;--success:#06d6a0;--danger:#ef476f;--warning:#ffd166;--info:#118ab2;--light:#f8f9fa;--dark:#212529;--gray:#6c757d;--light-gray:#e9ecef;--border-radius:12px;--box-shadow:0 8px 25px rgba(0, 0, 0, 0.1);--transition:all 0.3s ease;--diff-add-bg:rgba(6, 214, 160, 0.2);--diff-del-bg:rgba(239, 71, 111, 0.2);--line-num-bg:#f8f9fa;--line-num-text:#adb5bd;--code-font:'Consolas','Monaco','Courier New',monospace}*{margin:0;padding:0;box-sizing:border-box}body{font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif;display:flex;flex-direction:column;align-items:center;min-height:100vh;background:linear-gradient(135deg,#f5f7fa 0,#e4edf5 100%);color:var(--dark);padding:20px}.container{background-color:#fff;padding:30px 40px;border-radius:var(--border-radius);box-shadow:var(--box-shadow);text-align:center;width:100%;max-width:1400px;position:relative;overflow:hidden;display:flex;flex-direction:column;height:90vh}.container::before{content:'';position:absolute;top:0;left:0;right:0;height:5px;background:linear-gradient(90deg,var(--primary),var(--secondary))}h1{color:var(--primary);margin-bottom:20px;font-size:1.8em;display:flex;align-items:center;justify-content:center;gap:12px;flex-shrink:0}.diff-wrapper{display:flex;gap:15px;flex:1;overflow:hidden;margin-bottom:20px;position:relative}.panel{flex:1;display:flex;flex-direction:column;border:1px solid var(--light-gray);border-radius:8px;overflow:hidden;background:#fff}.panel-header{background:var(--light);padding:10px 15px;font-weight:600;color:var(--gray);border-bottom:1px solid var(--light-gray);display:flex;justify-content:space-between;align-items:center}.panel-body{position:relative;flex:1;overflow:hidden}textarea{width:100%;height:100%;padding:15px;border:none;resize:none;font-family:var(--code-font);font-size:14px;line-height:1.5;outline:0;color:var(--dark);text-align:left}.diff-result{width:100%;height:100%;overflow:auto;font-family:var(--code-font);font-size:14px;line-height:1.5;background-color:#fff;display:none;text-align:left}.diff-line{display:flex;width:100%;min-height:1.5em}.line-num{width:45px;flex-shrink:0;background-color:var(--line-num-bg);color:var(--line-num-text);text-align:right;padding:0 8px;user-select:none;border-right:1px solid #eee}.line-content{flex:1;padding:0 10px;white-space:pre-wrap;word-break:break-all}.diff-line.deleted{background-color:var(--diff-del-bg)}.diff-line.added{background-color:var(--diff-add-bg)}.diff-line.empty{background-color:#fcfcfc}.diff-line.empty .line-num{color:transparent}.controls{display:flex;justify-content:space-between;align-items:center;padding-top:20px;border-top:1px solid var(--light-gray);flex-shrink:0}.stats{font-size:.95em;font-weight:600}.stats span{margin-right:15px}.text-success{color:var(--success)}.text-danger{color:var(--danger)}.action-btn{background:linear-gradient(to right,var(--primary),var(--secondary));color:#fff;border:none;padding:12px 30px;border-radius:8px;cursor:pointer;font-size:1em;font-weight:600;display:flex;align-items:center;gap:8px;transition:var(--transition);box-shadow:0 4px 15px rgba(67,97,238,.3)}.action-btn:hover{transform:translateY(-2px);box-shadow:0 6px 20px rgba(67,97,238,.4)}.action-btn.secondary{background:#fff;color:var(--gray);border:1px solid var(--light-gray);box-shadow:none}.action-btn.secondary:hover{background:var(--light);color:var(--dark)}.hidden{display:none!important}@media (max-width:768px){.container{height:auto;min-height:90vh}.diff-wrapper{flex-direction:column;height:600px}.diff-result,textarea{min-height:300px}}.diff-line.modify-old{background-color:rgba(239,71,111,.15)}.diff-line.modify-new{background-color:rgba(6,214,160,.15)}.diff-text-del{background-color:#ffb3c0;text-decoration:line-through;border-radius:2px}.diff-text-add{background-color:#acf2bd;border-radius:2px;font-weight:700}footer{margin-top:20px;color:var(--gray);font-size:.9em;text-align:center;padding:15px}