diff --git a/nvim/init.lua b/nvim/init.lua
index 4f6b595..919ec39 100644
--- a/nvim/init.lua
+++ b/nvim/init.lua
@@ -159,7 +159,7 @@ vim.keymap.set("i", "<CR>", function()
     return vim.fn["coc#pum#visible"]() == 1 and vim.fn["coc#pum#confirm"]() or "<CR>"
 end, { expr = true, silent = true })
 
--- ── PIM floating windows (calendar / alot / abook) ───────────────────────────
+-- ── PIM floating windows (sideward T: left column overlay) ───────────────────
 local function _pim_scratch(label, err)
     vim.cmd("enew")
     vim.bo.buftype   = "nofile"
@@ -180,11 +180,13 @@ local function _pim_float(row, col, height, width, border)
     local buf = vim.api.nvim_create_buf(false, true)
     vim.api.nvim_open_win(buf, true, {
         relative = "editor",
-        row = row, col = col,
-        height = height, width = width,
-        style = "minimal",
-        border = border or "none",
-        zindex = 50,
+        row      = row,
+        col      = col,
+        height   = math.max(1, height),
+        width    = math.max(1, width),
+        style    = "minimal",
+        border   = border or "none",
+        zindex   = 50,
     })
     return vim.api.nvim_get_current_win()
 end
@@ -199,21 +201,25 @@ local function toggle_solo(key, cmd, label)
         _solo[key] = nil
         return
     end
-    local h = math.floor(vim.o.lines   * 0.85)
-    local w = math.floor(vim.o.columns * 0.85)
-    local r = math.floor((vim.o.lines   - h - 2) / 2)
-    local c = math.floor((vim.o.columns - w - 2) / 2)
+    local H = vim.o.lines - 2
+    local W = vim.o.columns
+    local h = math.max(1, math.floor(H * 0.85))
+    local w = math.max(1, math.floor(W * 0.85))
+    -- centre accounting for the 1-cell rounded border on each side
+    local r = math.max(0, math.floor((H - h - 2) / 2))
+    local c = math.max(0, math.floor((W - w - 2) / 2))
     local win_id = _pim_float(r, c, h, w, "rounded")
     local ok, err = pcall(vim.cmd, cmd)
     if not ok then _pim_scratch(label, err) end
     _solo[key] = win_id
 end
 
-vim.keymap.set("n", "n", function() toggle_solo("n", "terminal alot",  "alot")        end, { silent = true })
+vim.keymap.set("n", "n", function() toggle_solo("n", "terminal alot",  "alot")         end, { silent = true })
 vim.keymap.set("n", "g", function() toggle_solo("g", "Calendar",       "calendar.vim") end, { silent = true })
 vim.keymap.set("n", "f", function() toggle_solo("f", "terminal abook", "abook")        end, { silent = true })
 
--- r: full-screen tiled overlay (mail top, calendar bottom-left, abook bottom-right)
+-- r: sideward-T overlay — left column (bar of the T) with three stacked panes,
+--    document remains visible to the right (the stem of the T)
 local _pim_wins = {}
 
 local function toggle_pim()
@@ -223,21 +229,23 @@ local function toggle_pim()
         return
     end
 
-    local H      = vim.o.lines - 2
-    local W      = vim.o.columns
-    local mail_h = math.floor(H * 0.6)
-    local bot_h  = H - mail_h
-    local cal_w  = math.floor(W * 0.5)
+    local H     = vim.o.lines - 2
+    local col_w = math.min(vim.o.columns, math.max(90, math.floor(vim.o.columns * 0.45)))
 
-    local w1 = _pim_float(0, 0, mail_h, W)
+    -- divide column height: mail 40%, calendar 30%, abook remainder (≥ 10)
+    local mail_h = math.max(1, math.floor(H * 0.40))
+    local cal_h  = math.max(1, math.floor(H * 0.30))
+    local ab_h   = math.max(1, H - mail_h - cal_h)
+
+    local w1 = _pim_float(0,               0, mail_h, col_w)
     local ok, err = pcall(vim.cmd, "terminal alot")
     if not ok then _pim_scratch("alot", err) end
 
-    local w2 = _pim_float(mail_h, 0, bot_h, cal_w)
+    local w2 = _pim_float(mail_h,           0, cal_h,  col_w)
     ok, err = pcall(vim.cmd, "Calendar")
     if not ok then _pim_scratch("calendar.vim", err) end
 
-    local w3 = _pim_float(mail_h, cal_w, bot_h, W - cal_w)
+    local w3 = _pim_float(mail_h + cal_h,   0, ab_h,   col_w)
     ok, err = pcall(vim.cmd, "terminal abook")
     if not ok then _pim_scratch("abook", err) end