add year 0 row and Nebenkosten mitfinanzieren toggle

style.css

@@ -201,6 +201,51 @@ label {
 
 .unit.prefix { color: var(--text-muted); }
 
+/* ===== Toggle switch ===== */
+.toggle-group {
+  flex-direction: row;
+  align-items: center;
+  justify-content: space-between;
+}
+
+.toggle-label {
+  display: flex;
+  flex-direction: column;
+  gap: 0.1rem;
+  color: var(--text-muted);
+  font-size: 0.82rem;
+  font-weight: 500;
+  cursor: pointer;
+}
+
+.toggle-switch { cursor: pointer; flex-shrink: 0; }
+.toggle-switch input { display: none; }
+
+.toggle-track {
+  display: block;
+  width: 40px;
+  height: 22px;
+  background: rgba(255,255,255,0.1);
+  border-radius: 99px;
+  position: relative;
+  transition: background 0.2s;
+}
+
+.toggle-thumb {
+  position: absolute;
+  top: 3px; left: 3px;
+  width: 16px; height: 16px;
+  background: var(--text-muted);
+  border-radius: 50%;
+  transition: transform 0.2s, background 0.2s;
+}
+
+.toggle-switch input:checked + .toggle-track { background: var(--buy-muted); }
+.toggle-switch input:checked + .toggle-track .toggle-thumb {
+  transform: translateX(18px);
+  background: var(--buy);
+}
+
 /* ===== Range slider styling ===== */
 input[type="range"] {
   -webkit-appearance: none;