:root{--bg: #fafbfe;--surface: #ffffff;--surface-alt: #f0f2f8;--border: #e2e5f0;--border-focus: #7364d2;--text: #1c1b33;--text-muted: #6e6d82;--primary: #7364d2;--primary-hover: #5f4fc4;--primary-soft: rgba(115, 100, 210, .08);--primary-glow: rgba(115, 100, 210, .18);--danger: #dc4a57;--danger-soft: rgba(220, 74, 87, .08);--success: #2daf6a;--success-soft: rgba(45, 175, 106, .1);--radius: 14px;--radius-sm: 10px;--shadow-sm: 0 1px 3px rgba(28, 27, 51, .04);--shadow-md: 0 4px 20px rgba(28, 27, 51, .06);--shadow-lg: 0 8px 40px rgba(28, 27, 51, .08)}*{box-sizing:border-box;margin:0;padding:0}body{min-width:0;background:var(--bg)}button,input{font:inherit}.app{font-family:DM Sans,system-ui,-apple-system,sans-serif;min-height:100vh;display:flex;flex-direction:column;align-items:center;color:var(--text)}.topbar{width:100%;display:flex;align-items:center;justify-content:space-between;padding:0 clamp(16px,4vw,48px);height:60px;background:var(--surface);border-bottom:1px solid var(--border)}.logo{font-size:1.15rem;font-weight:700;text-decoration:none;color:var(--text);letter-spacing:-.3px}.logo-k{background:linear-gradient(135deg,var(--primary),#9f8cf7);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.nav-links{display:flex;gap:20px}.nav-links a{color:var(--text-muted);text-decoration:none;font-size:.85rem;font-weight:500;transition:color .2s}.nav-links a:hover{color:var(--text)}.hero{text-align:center;padding:52px 24px 8px}.hero h1{font-size:clamp(1.7rem,4vw,2.5rem);font-weight:800;letter-spacing:-.8px;background:linear-gradient(135deg,var(--text) 40%,var(--primary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.hero p{margin-top:10px;color:var(--text-muted);font-size:1rem;font-weight:400}.drop-zone{margin:36px auto 0;width:min(540px,calc(100% - 32px));display:flex;flex-direction:column;align-items:center;gap:20px;padding:64px 40px;border:2px dashed var(--border);border-radius:20px;background:var(--surface);box-shadow:var(--shadow-md);transition:border-color .3s,box-shadow .3s}.drop-zone:hover{border-color:var(--primary);box-shadow:var(--shadow-md),0 0 0 4px var(--primary-soft)}.drop-zone input{display:none}.drop-icon{width:64px;height:64px;border-radius:16px;background:linear-gradient(135deg,var(--primary-soft),rgba(159,140,247,.12));display:flex;align-items:center;justify-content:center}.select-btn{display:inline-flex;align-items:center;gap:10px;padding:16px 44px;font-size:1rem;font-weight:700;color:#fff;background:linear-gradient(135deg,var(--primary),#8b7de8);border:none;border-radius:var(--radius);cursor:pointer;transition:all .25s;box-shadow:0 4px 16px var(--primary-glow);letter-spacing:-.2px}.select-btn:hover{background:linear-gradient(135deg,var(--primary-hover),var(--primary));box-shadow:0 6px 24px #7364d24d;transform:translateY(-2px)}.select-btn:active{transform:translateY(0)}.select-btn:disabled{opacity:.5;cursor:not-allowed;transform:none}.drop-hint{color:var(--text-muted);font-size:.85rem;font-weight:500}.workspace{margin:28px auto 0;width:min(600px,calc(100% - 32px));display:flex;flex-direction:column;gap:12px}.file-list{display:flex;flex-direction:column;gap:8px}.file-card{display:flex;align-items:center;gap:12px;padding:14px 16px;background:var(--surface);border:1.5px solid var(--border);border-radius:var(--radius);cursor:grab;transition:all .2s;-webkit-user-select:none;user-select:none;box-shadow:var(--shadow-sm)}.file-card:hover{border-color:#cccbe0;box-shadow:var(--shadow-md)}.file-card:active{cursor:grabbing}.file-card.drag-over{border-color:var(--primary);background:var(--primary-soft);box-shadow:0 0 0 3px var(--primary-glow)}.file-card.file-error{border-color:#dc4a5740;background:var(--danger-soft)}.file-grip{color:#ccc;flex-shrink:0;cursor:grab;transition:color .2s}.file-card:hover .file-grip{color:#999}.file-icon{position:relative;flex-shrink:0;width:38px;height:42px;display:flex;align-items:center;justify-content:center}.file-ext{position:absolute;bottom:1px;font-size:.5rem;font-weight:800;color:var(--primary);letter-spacing:.5px;text-transform:uppercase}.file-info{flex:1;min-width:0}.file-info strong{display:block;font-size:.88rem;font-weight:600;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--text)}.file-info small{color:var(--text-muted);font-size:.78rem;font-weight:500}.error-text{color:var(--danger)}.file-actions{display:flex;gap:2px;flex-shrink:0}.icon-btn{width:30px;height:30px;display:flex;align-items:center;justify-content:center;background:none;border:1.5px solid transparent;border-radius:8px;color:#bbb;cursor:pointer;transition:all .15s;padding:0}.icon-btn:hover:not(:disabled){background:var(--surface-alt);color:var(--text-muted);border-color:var(--border)}.icon-btn:disabled{opacity:.2;cursor:not-allowed}.remove-btn:hover:not(:disabled){background:var(--danger-soft);color:var(--danger);border-color:#dc4a5733}.add-more{display:flex;align-items:center;gap:10px;padding-top:4px}.add-more input{display:none}.add-more-btn{display:inline-flex;align-items:center;gap:7px;padding:9px 18px;font-size:.82rem;font-weight:600;color:var(--primary);background:var(--primary-soft);border:1.5px solid transparent;border-radius:var(--radius-sm);cursor:pointer;transition:all .2s;letter-spacing:-.1px}.add-more-btn:hover{background:var(--primary-glow);border-color:#7364d226}.add-more-btn:disabled{opacity:.4;cursor:not-allowed}.clear-btn{padding:9px 14px;font-size:.82rem;font-weight:500;color:var(--text-muted);background:none;border:1.5px solid var(--border);border-radius:var(--radius-sm);cursor:pointer;transition:all .15s}.clear-btn:hover{color:var(--text);border-color:#c0c3d0;background:var(--surface-alt)}.merge-section{display:flex;flex-direction:column;align-items:center;gap:12px;padding:12px 0 0}.summary{color:var(--text-muted);font-size:.82rem;font-weight:500}.merge-btn{width:100%;display:flex;align-items:center;justify-content:center;gap:10px;padding:18px 48px;font-size:1.1rem;font-weight:700;color:#fff;background:linear-gradient(135deg,var(--primary),#8b7de8);border:none;border-radius:var(--radius);cursor:pointer;transition:all .25s;box-shadow:0 4px 20px var(--primary-glow);letter-spacing:-.2px}.merge-btn:hover:not(:disabled){background:linear-gradient(135deg,var(--primary-hover),var(--primary));box-shadow:0 6px 28px #7364d259;transform:translateY(-2px)}.merge-btn:active:not(:disabled){transform:translateY(0)}.merge-btn:disabled{opacity:.4;cursor:not-allowed;transform:none;box-shadow:none}.spinner{width:18px;height:18px;border:2.5px solid rgba(255,255,255,.3);border-top-color:#fff;border-radius:50%;animation:spin .7s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.privacy-bar{display:inline-flex;align-items:center;justify-content:center;gap:8px;margin-top:36px;padding:10px 20px;color:var(--text-muted);font-size:.78rem;font-weight:500;background:var(--surface);border:1px solid var(--border);border-radius:100px;box-shadow:var(--shadow-sm)}@media(max-width:640px){.hero{padding:36px 16px 4px}.drop-zone{padding:44px 20px;border-radius:16px}.select-btn{padding:14px 32px;font-size:.95rem}.file-card{padding:12px;gap:8px}.file-grip{display:none}.merge-btn{padding:16px 32px;font-size:1rem}.add-more{flex-wrap:wrap}}