diff --git a/src/zotero_kb/templates/index.html b/src/zotero_kb/templates/index.html
index 8ce8f5a..e7ceef8 100644
--- a/src/zotero_kb/templates/index.html
+++ b/src/zotero_kb/templates/index.html
@@ -141,67 +141,6 @@
         border-radius: 16px;
         color: var(--muted);
       }
-      .tree-node {
-        display: grid;
-        gap: 0.35rem;
-      }
-      .tree-row {
-        display: flex;
-        align-items: center;
-        gap: 0.45rem;
-      }
-      .tree-toggle {
-        width: 1.6rem;
-        min-width: 1.6rem;
-        height: 1.6rem;
-        padding: 0;
-        border-radius: 10px;
-        background: rgba(44, 110, 73, 0.08);
-        color: var(--accent-strong);
-      }
-      .tree-label {
-        width: 100%;
-        text-align: left;
-        border: 1px solid transparent;
-        border-radius: 12px;
-        padding: 0.55rem 0.7rem;
-        background: rgba(255, 255, 255, 0.6);
-        color: var(--ink);
-      }
-      .tree-label.active {
-        border-color: rgba(44, 110, 73, 0.22);
-        background: rgba(44, 110, 73, 0.12);
-      }
-      .tree-children {
-        display: grid;
-        gap: 0.35rem;
-        margin-left: 1rem;
-        padding-left: 0.6rem;
-        border-left: 1px dashed var(--line);
-      }
-      .collection-item {
-        display: grid;
-        gap: 0.35rem;
-        padding: 0.75rem;
-        border: 1px solid var(--line);
-        border-radius: 14px;
-        background: rgba(255, 255, 255, 0.62);
-      }
-      .checkbox-row {
-        display: flex;
-        align-items: flex-start;
-        gap: 0.6rem;
-      }
-      .checkbox-row input[type="checkbox"] {
-        width: auto;
-        margin-top: 0.3rem;
-      }
-      .action-bar {
-        display: grid;
-        gap: 0.55rem;
-        padding-top: 0.4rem;
-        border-top: 1px solid var(--line);
-      }
       .modal-shell[hidden] {
         display: none;
       }
@@ -242,6 +181,10 @@
       .modal-action-bar {
         border-top: 1px solid var(--line);
         border-bottom: 0;
+        position: sticky;
+        bottom: 0;
+        z-index: 2;
+        background: var(--surface);
       }
       .modal-header-actions {
         display: flex;
@@ -439,25 +382,25 @@
         projects: [],
         currentProjectId: null,
         currentCards: [],
-        collectionTree: [],
         isImportModalOpen: false,
-        selectedCollectionKey: null,
-        expandedCollectionKeys: new Set(),
-        selectedItemKeys: new Set(),
-        visibleCollectionItems: [],
       };
 
       const elements = {
         projectForm: document.getElementById("create-project-form"),
         projectStatus: document.getElementById("project-status"),
         projectList: document.getElementById("project-list"),
-        collectionStatus: document.getElementById("collection-status"),
-        collectionTree: document.getElementById("collection-tree"),
-        collectionItems: document.getElementById("collection-items"),
-        selectedCount: document.getElementById("selected-count"),
-        selectDescendantsButton: document.getElementById("select-descendants-button"),
-        clearSelectionButton: document.getElementById("clear-selection-button"),
-        importSelectedItemsButton: document.getElementById("import-selected-items-button"),
+        importModal: document.getElementById("import-modal"),
+        importModalOverlay: document.getElementById("import-modal-overlay"),
+        openImportModalButton: document.getElementById("open-import-modal-button"),
+        closeImportModalButton: document.getElementById("close-import-modal-button"),
+        importModalProjectLabel: document.getElementById("import-modal-project-label"),
+        modalSelectedCount: document.getElementById("modal-selected-count"),
+        modalCollectionTree: document.getElementById("modal-collection-tree"),
+        modalCollectionItems: document.getElementById("modal-collection-items"),
+        modalSelectDescendantsButton: document.getElementById("modal-select-descendants-button"),
+        modalClearSelectionButton: document.getElementById("modal-clear-selection-button"),
+        modalImportSelectedItemsButton: document.getElementById("modal-import-selected-items-button"),
+        previewPopover: document.getElementById("item-preview-popover"),
         currentProjectLabel: document.getElementById("current-project-label"),
         cardList: document.getElementById("card-list"),
         cardDetail: document.getElementById("card-detail"),
@@ -589,112 +532,6 @@
         `).join("");
       }
 
-      function renderCollectionTree() {
-        if (!state.collectionTree.length) {
-          elements.collectionTree.innerHTML = '<div class="empty">没有读取到 Zotero collections。</div>';
-          return;
-        }
-        elements.collectionTree.innerHTML = "";
-        for (const node of state.collectionTree) {
-          elements.collectionTree.appendChild(renderCollectionNode(node));
-        }
-      }
-
-      function renderCollectionNode(node) {
-        const wrapper = document.createElement("div");
-        wrapper.className = "tree-node";
-
-        const row = document.createElement("div");
-        row.className = "tree-row";
-
-        const toggle = document.createElement("button");
-        toggle.type = "button";
-        toggle.className = "tree-toggle";
-        toggle.textContent = node.children && node.children.length
-          ? (state.expandedCollectionKeys.has(node.collection_key) ? "−" : "+")
-          : "·";
-        toggle.disabled = !(node.children && node.children.length);
-        toggle.addEventListener("click", () => toggleCollectionExpanded(node.collection_key));
-
-        const label = document.createElement("button");
-        label.type = "button";
-        label.className = "tree-label" + (state.selectedCollectionKey === node.collection_key ? " active" : "");
-        label.innerHTML = `
-          <strong>${node.name}</strong>
-          <div class="meta">${node.descendant_item_count} 篇</div>
-        `;
-        label.addEventListener("click", () => selectCollection(node.collection_key));
-
-        row.appendChild(toggle);
-        row.appendChild(label);
-        wrapper.appendChild(row);
-
-        if (node.children && node.children.length && state.expandedCollectionKeys.has(node.collection_key)) {
-          const children = document.createElement("div");
-          children.className = "tree-children";
-          for (const child of node.children) {
-            children.appendChild(renderCollectionNode(child));
-          }
-          wrapper.appendChild(children);
-        }
-        return wrapper;
-      }
-
-      function renderCollectionItems() {
-        renderSelectedCount();
-        if (!state.selectedCollectionKey) {
-          elements.collectionItems.innerHTML = '<div class="empty">先点击一个 collection。</div>';
-          return;
-        }
-        if (!state.visibleCollectionItems.length) {
-          elements.collectionItems.innerHTML = '<div class="empty">当前目录及子目录下没有可导入文献。</div>';
-          return;
-        }
-
-        elements.collectionItems.innerHTML = "";
-        for (const item of state.visibleCollectionItems) {
-          const row = document.createElement("label");
-          row.className = "collection-item";
-          row.innerHTML = `
-            <div class="checkbox-row">
-              <input type="checkbox" ${state.selectedItemKeys.has(item.item_key) ? "checked" : ""} />
-              <div>
-                <strong>${item.title}</strong>
-                <div class="meta">${item.item_key} · ${item.year || "-"} · ${item.item_type || "-"}</div>
-                <p>${item.abstract || "暂无摘要"}</p>
-              </div>
-            </div>
-          `;
-          const checkbox = row.querySelector('input[type="checkbox"]');
-          checkbox.addEventListener("change", (event) => {
-            toggleItemSelection(item.item_key, event.target.checked);
-          });
-          elements.collectionItems.appendChild(row);
-        }
-      }
-
-      function renderSelectedCount() {
-        elements.selectedCount.textContent = `已选 ${state.selectedItemKeys.size} 篇`;
-      }
-
-      function toggleItemSelection(itemKey, checked) {
-        if (checked) {
-          state.selectedItemKeys.add(itemKey);
-        } else {
-          state.selectedItemKeys.delete(itemKey);
-        }
-        renderSelectedCount();
-      }
-
-      function toggleCollectionExpanded(collectionKey) {
-        if (state.expandedCollectionKeys.has(collectionKey)) {
-          state.expandedCollectionKeys.delete(collectionKey);
-        } else {
-          state.expandedCollectionKeys.add(collectionKey);
-        }
-        renderCollectionTree();
-      }
-
       async function loadProjects() {
         const projects = await api("/api/projects");
         state.projects = projects;
@@ -725,29 +562,6 @@
         await selectProject(state.currentProjectId);
       }
 
-      async function loadCollectionTree() {
-        const payload = await api("/api/zotero/collections/tree");
-        state.collectionTree = payload.collections || [];
-        if (!state.selectedCollectionKey && state.collectionTree.length) {
-          state.selectedCollectionKey = state.collectionTree[0].collection_key;
-          state.expandedCollectionKeys.add(state.selectedCollectionKey);
-        }
-        renderCollectionTree();
-        if (state.selectedCollectionKey) {
-          await selectCollection(state.selectedCollectionKey, false);
-        }
-      }
-
-      async function selectCollection(collectionKey, rerenderTree = true) {
-        state.selectedCollectionKey = collectionKey;
-        const payload = await api(`/api/zotero/collections/${collectionKey}/items?include_descendants=true`);
-        state.visibleCollectionItems = payload.items || [];
-        if (rerenderTree) {
-          renderCollectionTree();
-        }
-        renderCollectionItems();
-      }
-
       elements.projectForm.addEventListener("submit", async (event) => {
         event.preventDefault();
         const formData = new FormData(elements.projectForm);
@@ -766,25 +580,6 @@
         }
       });
 
-      async function importItemKeys(itemKeys) {
-        if (!state.currentProjectId) {
-          setStatus(elements.collectionStatus, "请先选择项目。", true);
-          return;
-        }
-        try {
-          const payload = await api(`/api/projects/${state.currentProjectId}/imports/item-keys`, {
-            method: "POST",
-            body: JSON.stringify({ item_keys: itemKeys }),
-          });
-          setStatus(elements.collectionStatus, `已导入 ${payload.imported_item_keys.length} 篇文献。`);
-          renderCards(payload.project_view.cards || []);
-          state.selectedItemKeys.clear();
-          renderCollectionItems();
-        } catch (error) {
-          setStatus(elements.collectionStatus, error.message, true);
-        }
-      }
-
       elements.reloadCardsButton.addEventListener("click", async () => {
         if (!state.currentProjectId) {
           return;
@@ -794,22 +589,6 @@
 
       elements.refreshProjectsButton.addEventListener("click", loadProjects);
 
-      elements.selectDescendantsButton.addEventListener("click", () => {
-        for (const item of state.visibleCollectionItems) {
-          state.selectedItemKeys.add(item.item_key);
-        }
-        renderCollectionItems();
-      });
-
-      elements.clearSelectionButton.addEventListener("click", () => {
-        state.selectedItemKeys.clear();
-        renderCollectionItems();
-      });
-
-      elements.importSelectedItemsButton.addEventListener("click", async () => {
-        await importItemKeys(Array.from(state.selectedItemKeys));
-      });
-
       elements.recommendForm.addEventListener("submit", async (event) => {
         event.preventDefault();
         if (!state.currentProjectId) {
@@ -859,9 +638,8 @@
       elements.recommendTab.addEventListener("click", () => activateTab("recommend"));
       elements.planTab.addEventListener("click", () => activateTab("plan"));
 
-      Promise.all([loadProjects(), loadCollectionTree()]).catch((error) => {
+      loadProjects().catch((error) => {
         setStatus(elements.projectStatus, error.message, true);
-        setStatus(elements.collectionStatus, error.message, true);
       });
     </script>
   </body>