:root{--bg: #0f1419;--surface: #1a2332;--border: #2d3a4f;--text: #e8edf4;--muted: #8b9cb3;--accent: #3d9cfd;--accent-dim: #2563a8;--success: #34d399;--error: #f87171;--radius: 12px;font-family:DM Sans,system-ui,sans-serif}*,*:before,*:after{box-sizing:border-box}.nav{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:.35rem .65rem;padding:1rem 1.25rem 0;font-size:.9rem}.nav a{color:var(--accent);text-decoration:none}.nav a:hover{text-decoration:underline}.nav__current{color:var(--text);font-weight:600}.nav__sep{color:var(--muted);-webkit-user-select:none;user-select:none}.split-plan{margin:1.5rem 0 0;padding-left:1.25rem;color:var(--muted);font-size:.92rem;line-height:1.65}.split-plan code{font-size:.85em;color:var(--text);background:var(--surface);padding:.12rem .35rem;border-radius:6px}.drop-zone--wide{max-width:none}body{margin:0;min-height:100vh;background:radial-gradient(ellipse 120% 80% at 50% -20%,#1e3a5f 0%,transparent 55%),var(--bg);color:var(--text);line-height:1.5}.app{max-width:880px;margin:0 auto;padding:2.5rem 1.25rem 3rem}.header{text-align:center;margin-bottom:2rem}.header h1{font-size:clamp(1.5rem,4vw,1.85rem);font-weight:700;letter-spacing:-.02em;margin:0 0 .75rem}.lead{margin:0 auto;max-width:42rem;color:var(--muted);font-size:.95rem}.grid{display:grid;gap:1.25rem}@media(min-width:640px){.grid{grid-template-columns:1fr 1fr}}.drop-zone{position:relative;border:2px dashed var(--border);border-radius:var(--radius);padding:1.75rem 1.25rem;background:var(--surface);cursor:pointer;transition:border-color .2s,background .2s,transform .15s;outline:none}.drop-zone:hover,.drop-zone:focus-visible{border-color:var(--accent-dim);background:#1f2a3d}.drop-zone:focus-visible{box-shadow:0 0 0 3px #3d9cfd59}.drop-zone--drag{border-color:var(--accent);background:#1f3048}.drop-zone--filled{border-style:solid;border-color:#34d39973}.drop-zone__icon{width:2.5rem;height:2.5rem;border-radius:10px;background:linear-gradient(135deg,var(--accent-dim),var(--accent));color:#fff;font-weight:700;font-size:1.1rem;display:flex;align-items:center;justify-content:center;margin-bottom:1rem}.drop-zone h2{font-size:1.05rem;font-weight:600;margin:0 0 .5rem}.drop-zone__hint{margin:0;font-size:.85rem;color:var(--muted)}.drop-zone__file{margin:.85rem 0 0;font-size:.9rem;color:var(--success);word-break:break-all}.actions{margin-top:2rem;text-align:center}.btn{font-family:inherit;font-size:1rem;font-weight:600;padding:.85rem 1.75rem;border-radius:10px;border:none;cursor:pointer;transition:opacity .2s,transform .1s}.btn:disabled{opacity:.45;cursor:not-allowed}.btn:not(:disabled):active{transform:scale(.98)}.btn--primary{background:linear-gradient(135deg,#2563eb,var(--accent));color:#fff;box-shadow:0 4px 20px #3d9cfd40}.btn--primary:not(:disabled):hover{filter:brightness(1.08)}.status{margin:1rem 0 0;min-height:1.5em;font-size:.9rem;color:var(--muted)}.status--error{color:var(--error)}