diff --git a/viewport/viewport.go b/viewport/viewport.go
index 57638f1..00a3250 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -104,9 +104,12 @@ type Model struct {
 	// and [HihglightPrevious] to navigate.
 	SelectedHighlightStyle lipgloss.Style
 
-	highlights           []highlightInfo
-	hiIdx                int
-	memoizedMatchedLines []string
+	// StyleLineFunc allows to return a [lipgloss.Style] for each line.
+	// The argument is the line index.
+	StyleLineFunc func(int) lipgloss.Style
+
+	highlights []highlightInfo
+	hiIdx      int
 }
 
 // GutterFunc can be implemented and set into [Model.LeftGutterFunc].
@@ -216,9 +219,16 @@ func (m Model) HorizontalScrollPercent() float64 {
 // Line endings will be normalized to '\n'.
 func (m *Model) SetContent(s string) {
 	s = strings.ReplaceAll(s, "\r\n", "\n") // normalize line endings
-	m.lines = strings.Split(s, "\n")
+	m.SetContentLines(strings.Split(s, "\n"))
+}
+
+// SetContentLines allows to set the lines to be shown instead of the content.
+// If a given line has a \n in it, it'll be considered a [Model.SoftWrap].
+// See also [Model.SetContent].
+func (m *Model) SetContentLines(lines []string) {
 	// if there's no content, set content to actual nil instead of one empty
 	// line.
+	m.lines = lines
 	if len(m.lines) == 1 && ansi.StringWidth(m.lines[0]) == 0 {
 		m.lines = nil
 	}
@@ -236,25 +246,38 @@ func (m Model) GetContent() string {
 	return strings.Join(m.lines, "\n")
 }
 
-// calculateLine taking soft wrapiing into account, returns the total viewable
+// calculateLine taking soft wraping into account, returns the total viewable
 // lines and the real-line index for the given yoffset.
 func (m Model) calculateLine(yoffset int) (total, idx int) {
 	if !m.SoftWrap {
-		return len(m.lines), yoffset
+		for i, line := range m.lines {
+			adjust := max(1, lipgloss.Height(line))
+			if yoffset >= total && yoffset < total+adjust {
+				idx = i
+			}
+			total += adjust
+		}
+		if yoffset >= total {
+			idx = len(m.lines)
+		}
+		return total, idx
 	}
-	maxWidth := m.maxWidth()
 
+	maxWidth := m.maxWidth()
 	var gutterSize int
 	if m.LeftGutterFunc != nil {
 		gutterSize = lipgloss.Width(m.LeftGutterFunc(GutterContext{}))
 	}
 	for i, line := range m.lines {
-		adjust := max(1, ansi.StringWidth(line)/(maxWidth-gutterSize))
+		adjust := max(1, lipgloss.Width(line)/(maxWidth-gutterSize))
 		if yoffset >= total && yoffset < total+adjust {
 			idx = i
 		}
 		total += adjust
 	}
+	if yoffset >= total {
+		idx = len(m.lines)
+	}
 	return total, idx
 }
 
@@ -310,6 +333,7 @@ func (m Model) visibleLines() (lines []string) {
 		bottom := clamp(pos+maxHeight, top, len(m.lines))
 		lines = make([]string, bottom-top)
 		copy(lines, m.lines[top:bottom])
+		lines = m.styleLines(lines, top)
 		lines = m.highlightLines(lines, top)
 	}
 
@@ -319,35 +343,47 @@ func (m Model) visibleLines() (lines []string) {
 
 	// if longest line fit within width, no need to do anything else.
 	if (m.xOffset == 0 && m.longestLineWidth <= maxWidth) || maxWidth == 0 {
-		return m.prependColumn(lines)
+		return m.setupGutter(lines)
 	}
 
 	if m.SoftWrap {
 		return m.softWrap(lines, maxWidth)
 	}
 
-	for i := range lines {
-		lines[i] = ansi.Cut(lines[i], m.xOffset, m.xOffset+maxWidth)
+	for i, line := range lines {
+		sublines := strings.Split(line, "\n") // will only have more than 1 if caller used [Model.SetContentLines].
+		for j := range sublines {
+			sublines[j] = ansi.Cut(sublines[j], m.xOffset, m.xOffset+maxWidth)
+		}
+		lines[i] = strings.Join(sublines, "\n")
 	}
-	return m.prependColumn(lines)
+	return m.setupGutter(lines)
 }
 
+// styleLines styles the lines using [Model.StyleLineFunc].
+func (m Model) styleLines(lines []string, offset int) []string {
+	if m.StyleLineFunc == nil {
+		return lines
+	}
+	for i := range lines {
+		lines[i] = m.StyleLineFunc(i + offset).Render(lines[i])
+	}
+	return lines
+}
+
+// highlightLines highlights the lines with [Model.HighlightStyle] and
+// [Model.SelectedHighlightStyle].
 func (m Model) highlightLines(lines []string, offset int) []string {
 	if len(m.highlights) == 0 {
 		return lines
 	}
 	for i := range lines {
-		if memoized := m.memoizedMatchedLines[i+offset]; memoized != "" {
-			lines[i] = memoized
-		} else {
-			ranges := makeHighlightRanges(
-				m.highlights,
-				i+offset,
-				m.HighlightStyle,
-			)
-			lines[i] = lipgloss.StyleRanges(lines[i], ranges...)
-			m.memoizedMatchedLines[i+offset] = lines[i]
-		}
+		ranges := makeHighlightRanges(
+			m.highlights,
+			i+offset,
+			m.HighlightStyle,
+		)
+		lines[i] = lipgloss.StyleRanges(lines[i], ranges...)
 		if m.hiIdx < 0 {
 			continue
 		}
@@ -365,6 +401,7 @@ func (m Model) highlightLines(lines []string, offset int) []string {
 
 func (m Model) softWrap(lines []string, maxWidth int) []string {
 	var wrappedLines []string
+	total := m.TotalLineCount()
 	for i, line := range lines {
 		idx := 0
 		for ansi.StringWidth(line) >= idx {
@@ -372,7 +409,7 @@ func (m Model) softWrap(lines []string, maxWidth int) []string {
 			if m.LeftGutterFunc != nil {
 				truncatedLine = m.LeftGutterFunc(GutterContext{
 					Index:      i + m.YOffset,
-					TotalLines: m.TotalLineCount(),
+					TotalLines: total,
 					Soft:       idx > 0,
 				}) + truncatedLine
 			}
@@ -383,16 +420,25 @@ func (m Model) softWrap(lines []string, maxWidth int) []string {
 	return wrappedLines
 }
 
-func (m Model) prependColumn(lines []string) []string {
+// setupGutter sets up the left gutter using [Moddel.LeftGutterFunc].
+func (m Model) setupGutter(lines []string) []string {
+	if m.LeftGutterFunc == nil {
+		return lines
+	}
+
+	offset := max(0, m.lineToIndex(m.YOffset))
+	total := m.TotalLineCount()
 	result := make([]string, len(lines))
-	for i, line := range lines {
-		if m.LeftGutterFunc != nil {
-			line = m.LeftGutterFunc(GutterContext{
-				Index:      i + m.YOffset,
-				TotalLines: m.TotalLineCount(),
-			}) + line
+	for i := range lines {
+		var line []string
+		for j, realLine := range strings.Split(lines[i], "\n") {
+			line = append(line, m.LeftGutterFunc(GutterContext{
+				Index:      i + offset,
+				TotalLines: total,
+				Soft:       j > 0,
+			})+realLine)
 		}
-		result[i] = line
+		result[i] = strings.Join(line, "\n")
 	}
 	return result
 }
@@ -564,7 +610,6 @@ func (m *Model) SetHighlights(matches [][]int) {
 	if len(matches) == 0 || len(m.lines) == 0 {
 		return
 	}
-	m.memoizedMatchedLines = make([]string, len(m.lines))
 	m.highlights = parseMatches(m.GetContent(), matches)
 	m.hiIdx = m.findNearedtMatch()
 	m.showHighlight()
@@ -572,7 +617,6 @@ func (m *Model) SetHighlights(matches [][]int) {
 
 // ClearHighlights clears previously set highlights.
 func (m *Model) ClearHighlights() {
-	m.memoizedMatchedLines = nil
 	m.highlights = nil
 	m.hiIdx = -1
 }
@@ -704,7 +748,7 @@ func clamp(v, low, high int) int {
 func maxLineWidth(lines []string) int {
 	result := 0
 	for _, line := range lines {
-		result = max(result, ansi.StringWidth(line))
+		result = max(result, lipgloss.Width(line))
 	}
 	return result
 }
diff --git a/viewport/viewport_test.go b/viewport/viewport_test.go
index 860d0d0..1e10838 100644
--- a/viewport/viewport_test.go
+++ b/viewport/viewport_test.go
@@ -562,3 +562,33 @@ func testHighlights(tb testing.TB, content string, re *regexp.Regexp, expect []h
 		}
 	}
 }
+
+func TestCalculateLine(t *testing.T) {
+	t.Run("simple", func(t *testing.T) {
+		vp := New(WithWidth(40), WithHeight(20))
+		vp.SetContent("foo\nbar")
+		total, idx := vp.calculateLine(0)
+		if total != 2 || idx != 0 {
+			t.Errorf("total: %d, idx: %d", total, idx)
+		}
+	})
+
+	t.Run("line breaks", func(t *testing.T) {
+		vp := New(WithWidth(40), WithHeight(20))
+		vp.SetContentLines([]string{"new\nbar", "foo", "another line", "multiple\nlines"})
+		total, idx := vp.calculateLine(6)
+		if total != 6 || idx != 4 {
+			t.Errorf("total: %d, idx: %d", total, idx)
+		}
+	})
+
+	t.Run("soft breaks", func(t *testing.T) {
+		vp := New(WithWidth(40), WithHeight(20))
+		vp.SoftWrap = true
+		vp.SetContent("super long line super long line super long line super long line super long line super long line super long line super long line super long line super long line super long line super long line super long line super\nlong line super long line super long line super long line")
+		total, idx := vp.calculateLine(10)
+		if total != 6 || idx != 2 {
+			t.Errorf("total: %d, idx: %d", total, idx)
+		}
+	})
+}