diff --git a/script.js b/script.js
index ea88e77..9756612 100644
--- a/script.js
+++ b/script.js
@@ -268,11 +268,11 @@ function renderCards() {
 // FILTER & SEARCH
 // ===========================
 let currentFilter    = 'all';
-let currentSubFilter = 'all';
+let activeSubFilters = new Set();
 
 function setFilter(category, btn) {
-  currentFilter    = category;
-  currentSubFilter = 'all';
+  currentFilter = category;
+  activeSubFilters.clear();
   visibleCount = POSTS_PER_PAGE;
   document.querySelectorAll('.filter-btn').forEach(b => b.classList.remove('active'));
   btn.classList.add('active');
@@ -281,10 +281,20 @@ function setFilter(category, btn) {
 }
 
 function setSubFilter(sub, btn) {
-  currentSubFilter = sub;
   visibleCount = POSTS_PER_PAGE;
-  document.querySelectorAll('.sub-filter-btn').forEach(b => b.classList.remove('active'));
-  btn.classList.add('active');
+  if (sub === 'all') {
+    activeSubFilters.clear();
+  } else {
+    if (activeSubFilters.has(sub)) {
+      activeSubFilters.delete(sub);
+    } else {
+      activeSubFilters.add(sub);
+    }
+  }
+  document.querySelectorAll('.sub-filter-btn').forEach(b => {
+    const id = b.dataset.sub;
+    b.classList.toggle('active', id === 'all' ? activeSubFilters.size === 0 : activeSubFilters.has(id));
+  });
   filterPosts();
 }
 
@@ -296,8 +306,8 @@ function renderSubFilters() {
   const subs = sortSubcategories((cat?.subcategories || []).filter(s => countPostsInSubcategory(currentFilter, s.id) > 0));
   if (!subs.length) { container.innerHTML = ''; return; }
   container.innerHTML =
-    `<button class="sub-filter-btn ${currentSubFilter === 'all' ? 'active' : ''}" onclick="setSubFilter('all',this)">Kaikki</button>` +
-    subs.map(s => `<button class="sub-filter-btn ${currentSubFilter === s.id ? 'active' : ''}" onclick="setSubFilter('${s.id}',this)">${s.fi}</button>`).join('');
+    `<button class="sub-filter-btn ${activeSubFilters.size === 0 ? 'active' : ''}" data-sub="all" onclick="setSubFilter('all',this)">Kaikki</button>` +
+    subs.map(s => `<button class="sub-filter-btn ${activeSubFilters.has(s.id) ? 'active' : ''}" data-sub="${s.id}" onclick="setSubFilter('${s.id}',this)">${s.fi}</button>`).join('');
 }
 
 function filterPosts() {
@@ -308,7 +318,7 @@ function filterPosts() {
   cards.forEach(card => {
     const matchesCat  = currentFilter === 'all' || card.dataset.category === currentFilter;
     const postSubs    = (card.dataset.subcategory || '').split(',').filter(Boolean);
-    const matchesSub  = currentSubFilter === 'all' || postSubs.includes(currentSubFilter);
+    const matchesSub  = activeSubFilters.size === 0 || postSubs.some(s => activeSubFilters.has(s));
     const title  = (card.querySelector('h3')?.textContent || '').toLowerCase();
     const desc   = (card.querySelector('p:not(.card-author)')?.textContent || '').toLowerCase();
     const subLbl = (card.dataset.subcategory || '').toLowerCase();