I got this working in D7 and I can set up a custom node template for a content type using node--my-content-type.tpl.php but I can't get it to work for say page--my-content-type.tpl.php or page--my-path.tpl.php in Backdrop
I created a sub theme for basis (haven't tried with out a sub theme but I guess I should) and this is what I got in my template.php file which I just copied from my D7 site and adjusted.
<?php
/**
* @file
* Foss Basis preprocess functions and theme function overrides.
*/
function foss_basis_preprocess_page(&$variables, $hook) {
if(isset($variables['page']['content']['system_main']['no_content'])) {
unset($variables['page']['content']['system_main']['no_content']);
}
// Page template suggestions based off of content types
if (isset($variables['node'])) {
$variables['theme_hook_suggestions'][] = 'page__type__'. $variables['node']->type;
$variables['theme_hook_suggestions'][] = "page__node__" . $variables['node']->nid;
}
// Page template suggestions based off URL alias
if (module_exists('path')) {
$alias = backdrop_get_path_alias(str_replace('/edit','',$_GET['q']));
if ($alias != $_GET['q']) {
$template_filename = 'page';
foreach (explode('/', $alias) as $path_part) {
$template_filename = $template_filename . '__' . $path_part;
$variables['theme_hook_suggestions'][] = $template_filename;
}
}
}
}
https://api.backdropcms.org/layouts says:
There is also an example:
So I think you can "tailor a content type via HTML/PHP code" in a Backdrop way.
I've been working with Backdrop over a year and a half. At the beginning I was also annoyed that some techniques with which I was accustomed to Drupal 7 did not work as before, but gradually got used to the new way and now I find that it is more comfortable and filled with many new possibilities.