"Finally, thanks to David Pogue whose unflagging enthusiasm and endurance is (sic) inspiring;"
Should be "are inspiring" – plural subject -> plural number of verb

Phone, not email

Point 18 third para reads:
"If you look at the document window now, you see that the email field has a red etc"

Point 18 third para should read:
"If you look at the document window now, you see that the phone field has a red etc"

"...whether HTML or XHTML is the best (sic) approach."
Use "better" when the choice is between two alternatives.

"Part 5, Appendixes...The last two appendices..."
Consistency required. Use either Anglicized form, "appendixes," or Latin form, "appendices."

"Even more importantly (sic), you'll learn about...."

"Importantly" is not an adverb modifying "learn." It is, in fact, an adjective; the beginning phrase of this sentence actually means, "And what is even more important...."

The correct version is therefore, "Even more important, you'll learn about...."

"...(like 2 and 3-column layouts)..."
Should be, "(like 2- and 3-column layouts)"

"quotes" should read "quotation marks." (A quote is the text between the quotation marks.)

..."words or phrases that appear inside of (sic) a larger paragraph or heading."
The "of" is superfluous.

"More importantly, you can't create..."
See previous post on this error (should be "more important" as it is a contraction of "What is more important...."

"Use the headline tags...like (sic) you would if..."
"Like" is a preposition, not a conjunction. The correct wording is, "Use the headline tags...as you would if...."

"...use the <div> and <span> tags (see page 18)."
Should be (...see page 20)."

"...make their software behave like (sic) browsers did circa 1999..."
Again, "like" is a preposition, not a conjunction.
Correct wording is, "...make their software behave the way browsers did circa 1999...."

"...an URL..."
"An" (as opposed to "a") works only if "URL" were pronounced "earl"; I know of no one who pronounces it this way.

See my previous comment about "an URL."
Also, in reference to first paragraph after "Linking a Style Sheet Using CSS": see my previous comment about "inside of."

"...(just like the ones on page 27)..."
Should be page 28.

"...enclose all of the CSS code inside quotes (sic)."
Should be: ""...enclose all of the CSS code inside quotation marks."
Quotes are what go inside quotation marks.

"Press Enter(Return) to create a new line, hit the Tab key, and type color :red;"
Should be "...and type color: red;"

"by selection the Reset option" should read "by selecting the Reset option."

"The remote, or live, site is a mirror image of the local site" should read "The remote, or live, site is a duplicate of the local site." If it were a mirror image, everything would be reversed.

"...you need a little help from the <span> tag (page 18)."
Should be: "(page 20)."

"See page 96 for more on this topic."
Should be: "See page 94-5 for more on this topic."

Another example of "inside of" ("of" is redundant).
More examples on pp. 71 (second paragraph and Note:) and 76 (line 23).

"...it covers the brief nanosecond..."
As opposed to the long nanosecond?

"...where child selectors can't be beat (sic)."
I know this is a colloquial form, but the correct grammar is "can't be beaten." Best to avoid this form altogether, and substitute "are unbeatable," or similar.

"stsyle" should read "style"

After closing the New CSS Rule window, the "CSS Rule definition" window appears.

Dangling participle: "closing" is dangling, because it does not refer to the doer. The "CSS Rule definition" is not what does the closing. The reader does the closing. The grammatically correct version is, After closing the New CSS Rule window, you will see the "CSS Rule definition" window....OR,
After you close the New CSS Rule window, you will see the "CSS Rule definition" window...

Driving Directions
"Chia Vet heaquarters (sic)"
should read:
"Chia Vet headquarters"

From the North
"3. Keep right at the fork and follow the signs to Morrisson (sic) St/City Center"
should read:
"3. Keep right at the fork and follow the signs to Morrison St/City Center"
and
"5. Keep right onto the rampt (sic) to Salem/I-T S (sic)"
should read:
"5. Keep right onto the ramp to Salem/I-5"

"...much like an outline has headings..."

"Like" is a preposition, not a conjunction. The grammatically correct version is:
"...much as an outline has headings..."

"These days, however, Dreamweaver's table feature is a much more superior method..."
This is one for the Department of Redundancy Department: "more superior"
is a double comparative. Correct version:
"These days, however, Dreamweaver's table feature is a much superior method..."

"A pop-up menu's overall look and placement is controlled by..."
should be:
"A pop-up menu's overall look and placement are controlled by..."

"oppositepage" should be "opposite page" (missing space)

second sentence reads... "The copyright notice item"... I believe that the example is using something that would better be referred to as "The recent Chia VEt announcements item"...