vdoc: minor css fix + add error message

cmd/tools/vdoc-resources/doc.css

@@ -260,6 +260,9 @@ body {
 	padding: 1rem;
 	overflow: hidden;
 }
+.doc-content p {
+	line-height: 1.4;
+}
 .doc-content a {
 	color: #2779bd;
 	color: var(--link-color);
@@ -267,6 +270,9 @@ body {
 .doc-content > .doc-node {
 	padding: 5rem 0 2rem 0;
 	margin-top: -4rem;
+	overflow: hidden;
+	word-break: break-all; /* IE11 */
+	word-break: break-word;
 }
 .doc-content > .doc-node.const:not(:first-child) {
 	padding-top: 0;
@@ -408,6 +414,11 @@ pre, code, pre code {
   font-size: 0.9rem;
   text-shadow: none;
   font-family: monospace;
+  background-color: #edf2f7;
+  background-color: var(--code-background-color);
+  border-radius: 0.25rem;
+}	
+pre code {
   direction: ltr;
   text-align: left;
   white-space: pre;
@@ -421,14 +432,13 @@ pre, code, pre code {
   -moz-hyphens: none;
   -ms-hyphens: none;
   hyphens: none;
-  background-color: #edf2f7;
-  background-color: var(--code-background-color);
   display: block;
-  border-radius: 0.25rem;
   overflow-x: auto;
+  padding: 1rem;
 }
-code, pre code {
-	padding: 1rem;
+code {
+  padding: 0.2rem;
+  vertical-align: middle;
 }
 pre {
   overflow: auto;

cmd/tools/vdoc-resources/normalize.css

@@ -39,7 +39,6 @@ strong {
 	font-weight: bolder;
 }
 
-code,
 kbd,
 samp {
 	font-family: monospace, monospace;

cmd/tools/vdoc.v

@@ -573,7 +573,12 @@ fn (mut cfg DocConfig) generate_docs_from_file() {
 	for dirpath in dirs {
 		cfg.vprintln('Generating docs for ${dirpath}...')
 		mut dcs := doc.generate(dirpath, cfg.pub_only, true) or {
-			panic(err)
+			mut err_msg := err
+			if errcode == 1 {
+				err_msg += ' Use the `-m` flag if you are generating docs of a directory with multiple modules inside.'
+			}
+			eprintln(err_msg)
+			exit(1)
 		}
 		if dcs.contents.len == 0 { continue }
 		if cfg.is_multi {