doc: move HTML CSS to a dedicated file default.css

doc/default.css

+.container {
+  margin-right: auto;
+  margin-left: auto;
+  width: 1070px;
+}
+body {
+  font-size: 14px;
+  line-height: 20px;
+  color: #666666;
+  background-color: #ffffff;
+}
+a {
+  color: #0088cc;
+  text-decoration: none;
+}
+a:hover {
+  color: #005580;
+  text-decoration: underline;
+}
+p {
+  margin: 0 0 10px;
+}
+h2,
+h3,
+h4 {
+  margin: 10px 0;
+  font-family: inherit;
+  font-weight: bold;
+  line-height: 1;
+  border-color: #D6E9C6;
+  color: #468847;
+  border-style: solid;
+  border-width: 0 0 1px;
+  padding-left: 0.5em;
+}
+
+h1 a,
+h2 a,
+h3 a,
+h4 a {
+  color: inherit;
+}
+h1 {
+  font-size: 30px;
+  line-height: 40px;
+}
+h2 {
+  font-size: 20px;
+  line-height: 40px;
+}
+h3 {
+  font-size: 18px;
+  line-height: 40px;
+}
+code,
+pre {
+  padding: 0 3px 2px;
+  font-family: monospace;
+  font-size: 12px;
+  color: #333333;
+  border-radius: 3px;
+}
+pre {
+  display: block;
+  padding: 9.5px;
+  margin: 0 0 10px;
+  font-size: 13px;
+  line-height: 20px;
+  word-break: break-all;
+  word-wrap: break-word;
+  white-space: pre;
+  white-space: pre-wrap;
+  background-color: #f5f5f5;
+  border: 1px solid #ccc;
+  border-radius: 4px;
+}
+
+code {
+  padding: 2px 4px;
+  color: #d14;
+  background-color: #f7f7f9;
+  border: 1px solid #e1e1e8;
+}
+pre code {
+  padding: 0;
+  color: inherit;
+  background-color: transparent;
+  border: 0;
+}
+.alert {
+  padding: 8px 35px 8px 14px;
+  margin-bottom: 20px;
+  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
+  background-color: #fcf8e3;
+  border: 1px solid #fbeed5;
+  border-radius: 4px;
+  color: #c09853;
+}
+
+.alert-danger,
+.alert-error {
+  background-color: #f2dede;
+  border-color: #eed3d7;
+  color: #b94a48;
+}
+.alert-info {
+  background-color: #d9edf7;
+  border-color: #bce8f1;
+  color: #3a87ad;
+}
+
+ul.toc {
+  list-style-type: none;
+}

doc/t2h.init

@@ -9,124 +9,7 @@ $EXTRA_HEAD =
 ';
 
 $CSS_LINES = $ENV{"FFMPEG_CSS"} || <<EOT;
-<style type="text/css">
-<!--
-.container {
-  margin-right: auto;
-  margin-left: auto;
-  width: 1070px;
-}
-body {
-  font-size: 14px;
-  line-height: 20px;
-  color: #333333;
-  background-color: #ffffff;
-}
-a {
-  color: #0088cc;
-  text-decoration: none;
-}
-a:hover {
-  color: #005580;
-  text-decoration: underline;
-}
-p {
-  margin: 0 0 10px;
-}
-h2,
-h3,
-h4 {
-  margin: 10px 0;
-  font-family: inherit;
-  font-weight: bold;
-  line-height: 1;
-  border-color: #D6E9C6;
-  color: #468847;
-  border-style: solid;
-  border-width: 0 0 1px;
-  padding-left: 0.5em;
-}
-
-h1 a,
-h2 a,
-h3 a,
-h4 a {
-  color: inherit;
-}
-h1 {
-  font-size: 30px;
-  line-height: 40px;
-}
-h2 {
-  font-size: 20px;
-  line-height: 40px;
-}
-h3 {
-  font-size: 18px;
-  line-height: 40px;
-}
-code,
-pre {
-  padding: 0 3px 2px;
-  font-family: monospace;
-  font-size: 12px;
-  color: #333333;
-  border-radius: 3px;
-}
-pre {
-  display: block;
-  padding: 9.5px;
-  margin: 0 0 10px;
-  font-size: 13px;
-  line-height: 20px;
-  word-break: break-all;
-  word-wrap: break-word;
-  white-space: pre;
-  white-space: pre-wrap;
-  background-color: #f5f5f5;
-  border: 1px solid #ccc;
-  border-radius: 4px;
-}
-
-code {
-  padding: 2px 4px;
-  color: #d14;
-  background-color: #f7f7f9;
-  border: 1px solid #e1e1e8;
-}
-pre code {
-  padding: 0;
-  color: inherit;
-  background-color: transparent;
-  border: 0;
-}
-.alert {
-  padding: 8px 35px 8px 14px;
-  margin-bottom: 20px;
-  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
-  background-color: #fcf8e3;
-  border: 1px solid #fbeed5;
-  border-radius: 4px;
-  color: #c09853;
-}
-
-.alert-danger,
-.alert-error {
-  background-color: #f2dede;
-  border-color: #eed3d7;
-  color: #b94a48;
-}
-.alert-info {
-  background-color: #d9edf7;
-  border-color: #bce8f1;
-  color: #3a87ad;
-}
-
-ul.toc {
-  list-style-type: none;
-}
--->
-</style>
+<link rel="stylesheet" type="text/css" href="default.css" />
 EOT
 
 my $TEMPLATE_HEADER = $ENV{"FFMPEG_HEADER"} || <<EOT;