:root{color-scheme:light dark;--bg: #ffffff;--fg: #1a1a1a;--muted: #6b7280;--border: #d1d5db;--accent: #2563eb;--accent-fg: #ffffff;--panel: #f9fafb}@media (prefers-color-scheme: dark){:root{--bg: #0f1115;--fg: #e5e7eb;--muted: #9ca3af;--border: #2d323b;--accent: #3b82f6;--accent-fg: #0f1115;--panel: #171a21}}:root[data-theme=light]{--bg: #ffffff;--fg: #1a1a1a;--muted: #6b7280;--border: #d1d5db;--accent: #2563eb;--accent-fg: #ffffff;--panel: #f9fafb}:root[data-theme=dark]{--bg: #0f1115;--fg: #e5e7eb;--muted: #9ca3af;--border: #2d323b;--accent: #3b82f6;--accent-fg: #0f1115;--panel: #171a21}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--fg);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif}.app{max-width:640px;margin:0 auto;padding:2.5rem 1.25rem 4rem}.header-row{display:flex;align-items:flex-start;justify-content:space-between;gap:1rem}header h1{margin:0 0 .25rem;font-size:1.75rem}.subtitle{color:var(--muted);margin:0 0 2rem;line-height:1.5}#theme-toggle{flex-shrink:0;display:flex;align-items:center;justify-content:center;width:2.25rem;height:2.25rem;padding:0;border:1px solid var(--border);border-radius:999px;background:var(--panel);color:var(--fg);cursor:pointer}#theme-toggle:hover{border-color:var(--accent)}#theme-toggle .icon-sun{display:none}#theme-toggle .icon-moon{display:block}@media (prefers-color-scheme: dark){:root:not([data-theme]) #theme-toggle .icon-sun{display:block}:root:not([data-theme]) #theme-toggle .icon-moon{display:none}}:root[data-theme=dark] #theme-toggle .icon-sun{display:block}:root[data-theme=dark] #theme-toggle .icon-moon{display:none}:root[data-theme=light] #theme-toggle .icon-sun{display:none}:root[data-theme=light] #theme-toggle .icon-moon{display:block}.dropzone{position:relative;border:2px dashed var(--border);border-radius:12px;padding:2rem 1rem;text-align:center;cursor:pointer;transition:border-color .15s ease,background .15s ease}.dropzone.dragover{border-color:var(--accent);background:var(--panel)}.dropzone input[type=file]{position:absolute;inset:0;opacity:0;cursor:pointer;width:100%;height:100%}#dropzone-label{margin:0;color:var(--muted);pointer-events:none}#file-list{list-style:none;margin:1rem 0 0;padding:0;text-align:left;font-size:.9rem}#file-list li{padding:.15rem 0;color:var(--fg)}.options{display:flex;flex-direction:column;gap:.75rem;margin:1.5rem 0;padding:1rem;background:var(--panel);border-radius:12px}.options label{display:flex;align-items:center;gap:.5rem;font-size:.95rem}.output-name{margin-top:.5rem;padding-top:.75rem;border-top:1px solid var(--border)}.output-name input[type=text],.output-name input[type=number]{flex:1;padding:.4rem .6rem;border-radius:6px;border:1px solid var(--border);background:var(--bg);color:var(--fg);font-size:.9rem}.output-name input[type=number]{flex:none;width:5rem}.option-hint{margin:.35rem 0 0;font-size:.8rem;color:var(--muted)}.actions{display:flex;gap:.75rem}#combine-btn{flex:1;padding:.75rem 1rem;border:none;border-radius:8px;background:var(--accent);color:var(--accent-fg);font-size:1rem;font-weight:600;cursor:pointer}#combine-btn:disabled{opacity:.5;cursor:not-allowed}.actions .secondary{padding:.75rem 1.25rem;border:1px solid var(--border);border-radius:8px;background:transparent;color:var(--fg);font-size:1rem;font-weight:600;cursor:pointer}.actions .secondary:hover{border-color:var(--accent);color:var(--accent)}.progress{margin-top:1.5rem}.progress-bar{height:8px;border-radius:4px;background:var(--panel);overflow:hidden;margin-bottom:.75rem}.progress-bar-fill{height:100%;width:0%;background:var(--accent);transition:width .2s ease}#log{max-height:260px;overflow-y:auto;background:var(--panel);border-radius:8px;padding:.75rem;font-size:.8rem;white-space:pre-wrap;word-break:break-word}