diff --git a/web/css/app.css b/web/css/app.css
index a091a28..ab9ddbd 100644
--- a/web/css/app.css
+++ b/web/css/app.css
@@ -91,7 +91,7 @@ code { font-family: var(--mono); font-size: 0.92em; }
   border-radius: 0;
 }
 .menu-btn:hover, .menu.open .menu-btn { background: var(--accent); color: #fff; }
-#btn-sidebar { width: 34px; border-radius: 3px; margin: 3px 0; }
+#btn-sidebar { width: 34px; border-radius: 0; margin: 3px 0; }
 #btn-sidebar:hover { background: #e0dcd8; }
 
 .menu-dropdown {
@@ -143,107 +143,34 @@ code { font-family: var(--mono); font-size: 0.92em; }
 .tb-label { font-size: 12px; margin-left: 4px; }
 
 /* ---------------------------------------------------------------------------
-   Sistema de botões "rich" (mesma linguagem visual do Rich Button do
-   spell.sh — gradientes, brilho interno, glow e micro-interações — porém 100%
-   CSS puro, sem React/Tailwind, derivado dos tokens de tema via color-mix +
-   light-dark, portanto compatível com os 21 temas e com CSP estrita).
+   Sistema de botões "light": flat e sóbrio — sem gradientes, brilhos, sombras
+   internas ou cantos arredondados. Fundo sólido derivado dos tokens de tema
+   (compatível com os 21 temas e CSP estrita); hover/active apenas tingem o
+   fundo com o tom de painel imediatamente mais escuro.
    --------------------------------------------------------------------------- */
 .btn {
-  position: relative;
-  isolation: isolate;
   font: inherit;
   font-size: 13px;
   color: var(--fg);
-  border: 1px solid color-mix(in oklab, var(--border) 70%, var(--fg) 30%);
-  border-radius: 8px;
+  border: 1px solid var(--border);
+  border-radius: 0;
   padding: 4px 12px;
   cursor: pointer;
-  background:
-    linear-gradient(180deg,
-      color-mix(in oklab, var(--panel-2), white 55%) 0%,
-      var(--panel-2) 48%,
-      color-mix(in oklab, var(--panel-2), var(--fg) 10%) 100%);
-  box-shadow:
-    inset 0 1px 0 light-dark(rgba(255, 255, 255, .85), rgba(255, 255, 255, .14)),
-    inset 0 -1px 0 color-mix(in oklab, var(--panel-2), var(--fg) 14%),
-    0 1px 2px rgba(0, 0, 0, .12),
-    0 2px 6px -2px rgba(0, 0, 0, .10);
-  text-shadow: 0 1px 0 light-dark(rgba(255, 255, 255, .7), rgba(0, 0, 0, .35));
-  transition: transform .12s ease, box-shadow .16s ease, filter .16s ease;
-}
-.btn::after { /* reflexo superior estilo "vidro" */
-  content: '';
-  position: absolute;
-  inset: 1px 1px 50% 1px;
-  z-index: -1;
-  border-radius: 7px 7px 10px 10px;
-  background: linear-gradient(180deg, light-dark(rgba(255, 255, 255, .5), rgba(255, 255, 255, .07)), transparent);
-  pointer-events: none;
-}
-.btn:hover {
-  transform: translateY(-1px);
-  filter: brightness(1.04) saturate(1.05);
-  box-shadow:
-    inset 0 1px 0 light-dark(rgba(255, 255, 255, .9), rgba(255, 255, 255, .18)),
-    inset 0 -1px 0 color-mix(in oklab, var(--panel-2), var(--fg) 16%),
-    0 3px 8px -1px rgba(0, 0, 0, .18),
-    0 6px 16px -6px rgba(0, 0, 0, .14);
-}
-.btn:active {
-  transform: translateY(1px) scale(.98);
-  filter: brightness(.97);
-  box-shadow:
-    inset 0 2px 5px rgba(0, 0, 0, .22),
-    inset 0 -1px 0 light-dark(rgba(255, 255, 255, .5), rgba(255, 255, 255, .08));
-}
-.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
-.btn:disabled {
-  opacity: .45;
-  cursor: default;
-  transform: none;
-  filter: saturate(.4);
-  box-shadow: inset 0 1px 0 light-dark(rgba(255, 255, 255, .6), rgba(255, 255, 255, .1));
+  background: var(--panel);
+  transition: background .12s ease, border-color .12s ease, color .12s ease;
 }
+.btn:hover { background: var(--panel-2); border-color: color-mix(in oklab, var(--border), var(--fg) 20%); }
+.btn:active { background: color-mix(in oklab, var(--panel-2), var(--fg) 8%); }
+.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
+.btn:disabled { opacity: .5; cursor: default; background: var(--panel); border-color: var(--border); }
 .btn-icon { display: inline-flex; align-items: center; justify-content: center; padding: 4px 10px; }
-.btn-primary {
-  color: #fff;
-  text-shadow: 0 1px 1px rgba(0, 0, 0, .25);
-  border-color: color-mix(in oklab, var(--accent), black 28%);
-  background:
-    linear-gradient(180deg,
-      color-mix(in oklab, var(--accent), white 26%) 0%,
-      var(--accent) 48%,
-      color-mix(in oklab, var(--accent), black 14%) 100%);
-  box-shadow:
-    inset 0 1px 0 rgba(255, 255, 255, .38),
-    inset 0 -1px 0 color-mix(in oklab, var(--accent), black 24%),
-    0 2px 8px -1px color-mix(in oklab, var(--accent) 55%, transparent),
-    0 1px 2px rgba(0, 0, 0, .18);
-}
-.btn-primary::after { background: linear-gradient(180deg, rgba(255, 255, 255, .28), transparent); }
-.btn-primary:hover {
-  box-shadow:
-    inset 0 1px 0 rgba(255, 255, 255, .45),
-    inset 0 -1px 0 color-mix(in oklab, var(--accent), black 26%),
-    0 4px 14px -2px color-mix(in oklab, var(--accent) 65%, transparent),
-    0 2px 4px rgba(0, 0, 0, .2);
-}
-.btn-danger {
-  color: #fff;
-  text-shadow: 0 1px 1px rgba(0, 0, 0, .25);
-  border-color: color-mix(in oklab, var(--danger), black 26%);
-  background:
-    linear-gradient(180deg,
-      color-mix(in oklab, var(--danger), white 24%) 0%,
-      var(--danger) 48%,
-      color-mix(in oklab, var(--danger), black 12%) 100%);
-  box-shadow:
-    inset 0 1px 0 rgba(255, 255, 255, .35),
-    inset 0 -1px 0 color-mix(in oklab, var(--danger), black 22%),
-    0 2px 8px -1px color-mix(in oklab, var(--danger) 50%, transparent);
-}
-.btn-danger::after { background: linear-gradient(180deg, rgba(255, 255, 255, .25), transparent); }
-.btn-small { font-size: 12px; padding: 2px 9px; border-radius: 6px; }
+.btn-primary { background: var(--accent); border-color: var(--accent); color: #fff; }
+.btn-primary:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }
+.btn-primary:active { background: color-mix(in oklab, var(--accent-dark), black 12%); border-color: color-mix(in oklab, var(--accent-dark), black 12%); color: #fff; }
+.btn-danger { background: var(--danger); border-color: var(--danger); color: #fff; }
+.btn-danger:hover { background: color-mix(in oklab, var(--danger), black 12%); border-color: color-mix(in oklab, var(--danger), black 12%); color: #fff; }
+.btn-danger:active { background: color-mix(in oklab, var(--danger), black 20%); color: #fff; }
+.btn-small { font-size: 12px; padding: 2px 9px; }
 .fmt { min-width: 32px; justify-content: center; font-size: 13px; }
 #fmt-tools.disabled { opacity: .45; pointer-events: none; }
 
@@ -251,49 +178,32 @@ code { font-family: var(--mono); font-size: 0.92em; }
   font: inherit;
   font-size: 13px;
   color: var(--fg);
-  background:
-    linear-gradient(180deg,
-      color-mix(in oklab, var(--panel), white 40%) 0%,
-      var(--panel) 50%,
-      color-mix(in oklab, var(--panel), var(--fg) 6%) 100%);
-  border: 1px solid color-mix(in oklab, var(--border) 70%, var(--fg) 30%);
-  border-radius: 8px;
+  background: var(--panel);
+  border: 1px solid var(--border);
+  border-radius: 0;
   padding: 4px 8px;
-  box-shadow: inset 0 1px 0 light-dark(rgba(255, 255, 255, .8), rgba(255, 255, 255, .12)), 0 1px 2px rgba(0, 0, 0, .1);
 }
 
 .segmented {
   display: inline-flex;
-  border: 1px solid color-mix(in oklab, var(--border) 70%, var(--fg) 30%);
-  border-radius: 9px;
+  border: 1px solid var(--border);
   overflow: hidden;
-  background: color-mix(in oklab, var(--panel-2), var(--fg) 6%);
-  box-shadow: inset 0 1px 3px rgba(0, 0, 0, .12);
-  padding: 2px;
-  gap: 2px;
+  background: var(--panel);
 }
 .segmented .seg {
   border: 0;
+  border-right: 1px solid var(--border-soft);
   background: transparent;
   font: inherit;
   font-size: 12px;
   padding: 4px 14px;
   cursor: pointer;
   color: var(--muted);
-  border-radius: 7px;
-  transition: background .15s ease, color .15s ease, box-shadow .15s ease;
-}
-.segmented .seg:hover { color: var(--fg); background: color-mix(in oklab, var(--panel), transparent 35%); }
-.segmented .seg.active {
-  background:
-    linear-gradient(180deg,
-      color-mix(in oklab, var(--accent), white 22%) 0%,
-      var(--accent) 55%,
-      color-mix(in oklab, var(--accent), black 10%) 100%);
-  color: #fff;
-  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .35), 0 1px 4px color-mix(in oklab, var(--accent) 50%, transparent);
-  text-shadow: 0 1px 1px rgba(0, 0, 0, .25);
+  transition: background .15s ease, color .15s ease;
 }
+.segmented .seg:last-child { border-right: 0; }
+.segmented .seg:hover { color: var(--fg); background: var(--panel-2); }
+.segmented .seg.active { background: var(--accent); color: #fff; }
 
 /* ---------------------------------------------------------------- layout */
 #layout { display: flex; flex: 1 1 auto; min-height: 0; }
@@ -336,7 +246,7 @@ body.sidebar-off #sidebar { display: none; }
   border: 1px solid var(--border);
   background: var(--panel);
   color: var(--accent-dark);
-  border-radius: 10px;
+  border-radius: 0;
   padding: 1px 8px;
   cursor: pointer;
 }
@@ -686,7 +596,7 @@ body.no-gutter #gutter { display: none; }
   height: 16px;
   line-height: 15px;
   text-align: center;
-  border-radius: 3px;
+  border-radius: 0;
   font-size: 10px;
 }
 .tab-close:hover { background: var(--danger); color: #fff; }
@@ -731,7 +641,7 @@ body.no-gutter #gutter { display: none; }
   color: var(--muted);
   cursor: pointer;
   padding: 0 4px;
-  border-radius: 3px;
+  border-radius: 0;
   visibility: hidden;
 }
 .tree-row:hover .tree-menu, .tree-row.active .tree-menu { visibility: visible; }
@@ -1861,7 +1771,7 @@ html[data-theme="carbon-paper"] #revisions-list li:hover { background: #e6e5dd;
   font-size: 11px;
   color: var(--muted);
   padding: 1px 4px;
-  border-radius: 4px;
+  border-radius: 0;
 }
 .ftree-act:hover { background: var(--accent); color: #fff; }
 .files-list {
diff --git a/web/sw.js b/web/sw.js
index 32d1046..a069def 100644
--- a/web/sw.js
+++ b/web/sw.js
@@ -1,7 +1,7 @@
 /* Service Worker do Notas — caches versionados.
  * BUMP de CACHE em todo deploy que mude shell/assets (o activate limpa os antigos).
  */
-const CACHE = 'notas-shell-v11';
+const CACHE = 'notas-shell-v12';
 const SHELL = [
   '/',
   '/css/app.css',