diff --git a/R/add_header_above.R b/R/add_header_above.R
index 5a3c31a..e50261e 100644
--- a/R/add_header_above.R
+++ b/R/add_header_above.R
@@ -32,11 +32,7 @@
   if (is.null(header)) return(kable_input)
   table_info <- magic_mirror(kable_input)
   kable_xml <- read_xml(as.character(kable_input), options = c("COMPACT"))
-  # somehow xml2 cannot directly search by name here (it will result in a crash)
-  kable_xml_thead <- xml_child(kable_xml, 1)
-  if (xml_name(kable_xml_thead) != "thead") {
-    kable_xml_thead <- xml_child(kable_xml, 2)
-  }
+  kable_xml_thead <- xml_tpart(kable_xml, "thead")
 
   header <- standardize_header_input(header)
 
diff --git a/R/add_indent.R b/R/add_indent.R
index c88b33d..18fdcd1 100644
--- a/R/add_indent.R
+++ b/R/add_indent.R
@@ -7,13 +7,14 @@
     return(kable_input)
   }
   if (kable_format == "html") {
-    return(kable_input)
+    return(add_indent_html(kable_input, positions))
   }
   if (kable_format == "latex") {
     return(add_indent_latex(kable_input, positions))
   }
 }
 
+# Add indentation for LaTeX
 add_indent_latex <- function(kable_input, positions) {
   table_info <- attr(kable_input, "original_kable_meta")
   if (is.null(table_info)) {
@@ -39,3 +40,38 @@
 latex_indent_unit <- function(rowtext) {
   paste0("\\\\hspace{1em}", rowtext)
 }
+
+# Add indentation for HTML
+add_indent_html <- function(kable_input, positions) {
+  kable_attrs <- attributes(kable_input)
+
+  kable_xml <- read_xml(as.character(kable_input), options = "COMPACT")
+  kable_tbody <- xml_tpart(kable_xml, "tbody")
+
+  group_header_rows <- attr(kable_input, "group_header_rows")
+  if (!is.null(group_header_rows)) {
+    positions <- positions_corrector(positions, group_header_rows,
+                                     length(xml_children(kable_tbody)))
+  }
+  for (i in positions) {
+    node_to_edit <- xml_child(xml_children(kable_tbody)[[i]], 1)
+    if (!xml_has_attr(node_to_edit, "indentLevel")) {
+      xml_attr(node_to_edit, "style") <- paste(
+        xml_attr(node_to_edit, "style"), "padding-left: 2em;"
+      )
+      xml_attr(node_to_edit, "indentLevel") <- 1
+    } else {
+      indentLevel <- as.numeric(xml_attr(node_to_edit, "indentLevel"))
+      xml_attr(node_to_edit, "style") <- sub(
+        paste0("padding-left: ", indentLevel * 2, "em;"),
+        paste0("padding-left: ", (indentLevel + 1) * 2, "em;"),
+        xml_attr(node_to_edit, "style")
+      )
+      xml_attr(node_to_edit, "indentLevel") <- indentLevel + 1
+    }
+  }
+  out <- structure(as.character(kable_xml), format = "html",
+                   class = "knitr_kable")
+  attributes(out) <- kable_attrs
+  return(out)
+}
diff --git a/R/group_rows.R b/R/group_rows.R
new file mode 100644
index 0000000..9827811
--- /dev/null
+++ b/R/group_rows.R
@@ -0,0 +1,51 @@
+#' Put a few rows of a table into one category
+#'
+#' @export
+group_rows <- function(kable_input, group_label, start_row, end_row) {
+  kable_format <- attr(kable_input, "format")
+  if (!kable_format %in% c("html", "latex")) {
+    message("Currently generic markdown table using pandoc is not supported.")
+    return(kable_input)
+  }
+  if (kable_format == "html") {
+    return(group_rows_html(kable_input, group_label, start_row, end_row))
+  }
+  if (kable_format == "latex") {
+    return(group_rows_latex(kable_input, group_label, start_row, end_row))
+  }
+}
+
+group_rows_html <- function(kable_input, group_label, start_row, end_row) {
+  if (!is.numeric(c(start_row, end_row))) {
+    stop("Start_row and end_row must be numeric position of rows (excluding",
+         "header rows and other group-title rows). ")
+  }
+  kable_attrs <- attributes(kable_input)
+  kable_xml <- read_xml(as.character(kable_input), options = "COMPACT")
+  kable_tbody <- xml_tpart(kable_xml, "tbody")
+
+  group_header_rows <- attr(kable_input, "group_header_rows")
+  group_seq <- seq(start_row, end_row)
+  if (!is.null(group_header_rows)) {
+    group_seq <- positions_corrector(group_seq, group_header_rows,
+                                     length(xml_children(kable_tbody)))
+  }
+
+  # Insert a group header row
+  starting_node <- xml_child(kable_tbody, group_seq[1])
+  kable_ncol <- length(xml_children(starting_node))
+  group_header_row_text <- paste0(
+    '<tr groupLength="', length(group_seq), '"><td colspan="',
+    kable_ncol, '"><strong>', group_label, "</strong></td></tr>"
+  )
+  group_header_row <- read_xml(group_header_row_text, options = "COMPACT")
+  xml_add_sibling(starting_node, group_header_row, .where = "before")
+
+  # add indentations to items
+  out <- structure(as.character(kable_xml), format = "html",
+                   class = "knitr_kable")
+  attributes(out) <- kable_attrs
+  attr(out, "group_header_rows") <- c(attr(out, "group_header_rows"), group_seq[1])
+  out <- add_indent(out, positions = seq(start_row, end_row))
+  return(out)
+}
diff --git a/R/kableExtra-package.R b/R/kableExtra-package.R
index 904c032..79f77e5 100644
--- a/R/kableExtra-package.R
+++ b/R/kableExtra-package.R
@@ -4,6 +4,7 @@
 #' str_extract str_replace_all str_trim str_extract_all
 #' @importFrom xml2 read_xml xml_attr xml_has_attr xml_attr<- read_html
 #' xml_child xml_children xml_name xml_add_sibling xml_add_child xml_text
+#' xml_text<-
 #' @importFrom rvest html_table
 #' @importFrom knitr knit_meta_add
 #' @importFrom rmarkdown latex_dependency
diff --git a/R/util.R b/R/util.R
index 9023f4b..50129a7 100644
--- a/R/util.R
+++ b/R/util.R
@@ -30,3 +30,21 @@
 usepackage_latex <- function(name, options = NULL) {
   invisible(knit_meta_add(list(latex_dependency(name, options))))
 }
+
+# Find the right xml section. Since xml_child + search name will result in a
+# crash (at least on my machine), here is a helper function.
+xml_tpart <- function(x, part) {
+  xchildren <- xml_children(x)
+  children_names <- xml_name(xchildren)
+  return(xchildren[[which(children_names == part)]])
+}
+
+positions_corrector <- function(positions, group_header_rows, n_row) {
+  pc_matrix <- data.frame(row_id = 1:n_row)
+  pc_matrix$group_header <- pc_matrix$row_id %in% group_header_rows
+  pc_matrix$adj <- cumsum(pc_matrix$group_header)
+  pc_matrix$old_id <- cumsum(!pc_matrix$group_header)
+  pc_matrix$old_id[duplicated(pc_matrix$old_id)] <- NA
+  adjust_numbers <- pc_matrix$adj[pc_matrix$old_id %in% positions]
+  return(adjust_numbers + positions)
+}