fix(single): restore Zibll float dual-column and article chrome

Align single-post layout/visuals with Zibll: fix sidebar-over-content
float geometry (position:unset, 311px token, kill Bootstrap/container
padding and the 280px sidebar override), demote theme-box to spacing-
only, unify breadcrumb/cover/graphic utilities, and split aksrt-single
render helpers under the file-size limit.

assets/css/frontend/zibll-utilities.css

@@ -49,6 +49,132 @@
   transform: translate(-50%, -50%);
 }
 
+/* Zibll abs-center position variants (main.css) */
+.abs-center.left-bottom,
+.abs-center.right-bottom,
+.abs-center.conter-bottom {
+  top: auto;
+  transform: unset;
+  bottom: 0;
+}
+
+.abs-center.left-bottom {
+  left: 0;
+  right: auto;
+  text-align: left;
+}
+
+.abs-center.right-bottom,
+.abs-center.right-conter {
+  left: auto;
+  right: 0;
+  text-align: right;
+}
+
+/* Graphic ratio box (cover / related thumbs) — Zibll .graphic */
+.graphic,
+.page-cover {
+  text-shadow: 0 0 5px rgba(0, 0, 0, 0.2);
+  --main-color: #fff;
+  color: #fff;
+  position: relative;
+  overflow: hidden;
+  box-shadow: 0 0 10px var(--main-shadow, rgba(116, 116, 116, 0.08));
+  padding: 0;
+  padding-bottom: 70%;
+  border-radius: var(--main-radius, var(--radius, 8px));
+}
+
+.graphic > .fit-cover,
+.graphic > img.fit-cover {
+  position: absolute;
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  inset: 0;
+}
+
+.fit-cover {
+  object-fit: cover;
+  max-width: 100%;
+}
+
+/* title-h-left underline bar (Zibll) */
+.title-h-left {
+  position: relative;
+  padding-bottom: 8px;
+}
+
+.title-h-left:before {
+  transition: 0.4s;
+  transform-origin: left;
+  position: absolute;
+  content: "";
+  width: 40px;
+  height: 3px;
+  background: var(--theme-color, var(--focus-color, #f04494));
+  left: 0;
+  bottom: 3px;
+  border-radius: 5px;
+  box-shadow: 1px 1px 3px -1px var(--theme-color, var(--focus-color, #f04494));
+}
+
+/* line-form-line — Zibll absolute bottom rule (author meta separator) */
+.line-form-line,
+.line-form-line:before {
+  position: absolute;
+  bottom: 0;
+  left: 0;
+  height: 1px;
+  width: 100%;
+  transition: 0.8s;
+  background: var(--main-border-color, rgba(50, 50, 50, 0.06));
+}
+
+.line-form-line:before {
+  content: "";
+  width: 0;
+  background: var(--focus-color, #f04494);
+}
+
+/* Avatar size primitive */
+.avatar-img {
+  position: relative;
+  display: inline-block;
+  flex-shrink: 0;
+  --this-size: 38px;
+  width: var(--this-size);
+  height: var(--this-size);
+}
+
+.avatar-img .avatar,
+.avatar-img img {
+  width: 100%;
+  height: 100%;
+  border-radius: 50%;
+  object-fit: cover;
+}
+
+.avatar-lg {
+  --this-size: 80px;
+}
+
+.avatar-md {
+  --this-size: 55px;
+}
+
+.avatar-mini {
+  --this-size: 20px;
+}
+
+.shrink0 {
+  flex-shrink: 0;
+}
+
+.opacity8 {
+  opacity: 0.8;
+}
+
 /* Typography / color helpers */
 .muted-color { color: var(--muted-color, var(--color-ink-3)); }
 .muted-2-color { color: var(--muted-2-color, var(--color-ink-4)); }