diff --git a/src/components/NavBar.vue b/src/components/NavBar.vue
index 905d7cb..8f03836 100644
--- a/src/components/NavBar.vue
+++ b/src/components/NavBar.vue
@@ -1,13 +1,16 @@
 <script setup>
-import { Sun, Moon } from 'lucide-vue-next';
+import { Sun, Moon, Layers } from 'lucide-vue-next';
 import { ref, onMounted } from 'vue';
+import { useSettings } from '../composables/useSettings';
 
+const { showProjections, toggleProjections } = useSettings();
 const isDark = ref(true);
 
 const setTheme = (dark) => {
   isDark.value = dark;
   const theme = dark ? 'dark' : 'light';
   document.documentElement.dataset.theme = theme;
+  localStorage.setItem('theme', theme);
 };
 
 const toggleTheme = () => {
@@ -15,7 +18,12 @@ const toggleTheme = () => {
 };
 
 onMounted(() => {
-  setTheme(true);
+  const savedTheme = localStorage.getItem('theme');
+  if (savedTheme) {
+    setTheme(savedTheme === 'dark');
+  } else {
+    setTheme(true);
+  }
 });
 </script>
 
@@ -26,6 +34,11 @@ onMounted(() => {
     </div>
 
     <div class="nav-container">
+      <!-- Projections Toggle -->
+      <button class="btn-neon nav-btn icon-only" @click="toggleProjections" :title="showProjections ? 'Ukryj rzuty' : 'Pokaż rzuty'" :class="{ active: showProjections }">
+        <Layers :size="20" />
+      </button>
+
       <!-- Theme Toggle -->
       <button class="btn-neon nav-btn icon-only" @click="toggleTheme" :title="isDark ? 'Przełącz na jasny' : 'Przełącz na ciemny'">
         <Sun v-if="isDark" :size="20" />
@@ -86,7 +99,13 @@ onMounted(() => {
   transition: all 0.3s ease;
 }
 
-.nav-btn:hover {
+.nav-btn:hover,
+.nav-btn.active {
   background: rgba(255, 255, 255, 0.2);
 }
+
+.nav-btn.active {
+  color: var(--color-primary);
+  box-shadow: 0 0 10px rgba(255, 255, 255, 0.1);
+}
 </style>
diff --git a/src/components/common/Line3D.vue b/src/components/common/Line3D.vue
new file mode 100644
index 0000000..6b9810a
--- /dev/null
+++ b/src/components/common/Line3D.vue
@@ -0,0 +1,59 @@
+<script setup>
+import { computed } from 'vue';
+
+const props = defineProps({
+  start: {
+    type: Object,
+    required: true // {x, y, z}
+  },
+  end: {
+    type: Object,
+    required: true // {x, y, z}
+  },
+  color: {
+    type: String,
+    default: 'var(--text-color, #fff)'
+  },
+  thickness: {
+    type: Number,
+    default: 1
+  }
+});
+
+const style = computed(() => {
+  const dx = props.end.x - props.start.x;
+  const dy = props.end.y - props.start.y;
+  const dz = props.end.z - props.start.z;
+  
+  const length = Math.sqrt(dx * dx + dy * dy + dz * dz);
+  
+  if (length === 0) return {};
+
+  const midX = (props.start.x + props.end.x) / 2;
+  const midY = (props.start.y + props.end.y) / 2;
+  const midZ = (props.start.z + props.end.z) / 2;
+  
+  // Rotation
+  // Yaw (around Y axis)
+  const yaw = Math.atan2(dz, dx);
+  // Pitch (around Z axis)
+  const pitch = Math.atan2(dy, Math.sqrt(dx * dx + dz * dz));
+  
+  return {
+    width: `${length}px`,
+    height: `${props.thickness}px`,
+    backgroundColor: props.color,
+    position: 'absolute',
+    top: '0',
+    left: '0',
+    transformOrigin: 'center center',
+    transform: `translate3d(${midX}px, ${midY}px, ${midZ}px) rotateY(${-yaw}rad) rotateZ(${pitch}rad) translate(-50%, -50%)`,
+    opacity: 0.3, // Delicate
+    pointerEvents: 'none'
+  };
+});
+</script>
+
+<template>
+  <div class="line-3d" :style="style"></div>
+</template>
diff --git a/src/composables/useSettings.js b/src/composables/useSettings.js
new file mode 100644
index 0000000..f68cbf9
--- /dev/null
+++ b/src/composables/useSettings.js
@@ -0,0 +1,25 @@
+import { ref } from 'vue';
+
+let initialShowProjections = false;
+try {
+  const stored = localStorage.getItem('showProjections');
+  if (stored !== null) {
+    initialShowProjections = stored === 'true';
+  }
+} catch (e) {}
+
+const showProjections = ref(initialShowProjections);
+
+export function useSettings() {
+  const toggleProjections = () => {
+    showProjections.value = !showProjections.value;
+    try {
+      localStorage.setItem('showProjections', String(showProjections.value));
+    } catch (e) {}
+  };
+
+  return {
+    showProjections,
+    toggleProjections
+  };
+}