diff --git a/src/inc/visual.php b/src/inc/visual.php
new file mode 100644
index 0000000..02a3457
--- /dev/null
+++ b/src/inc/visual.php
@@ -0,0 +1,192 @@
+<?php
+class visual {
+  const VIEW_ADMIN = 0;
+  const VIEW_WORKER = 1;
+
+  // Old:
+  /*const YES = "✓";
+  const NO = "✗";*/
+
+  // New:
+  const YES = "✓";
+  const NO = "X";
+
+  public static function snackbar($msg, $timeout = 10000, $printHTML = true) {
+    if ($printHTML) echo '<div class="mdl-snackbar mdl-js-snackbar">
+      <div class="mdl-snackbar__text"></div>
+      <button type="button" class="mdl-snackbar__action"></button>
+    </div>';
+    echo '<script>
+    window.addEventListener("load", function() {
+      var notification = document.querySelector(".mdl-js-snackbar");
+      notification.MaterialSnackbar.showSnackbar(
+        {
+          message: "'.security::htmlsafe($msg).'",
+          timeout: '.(int)$timeout.'
+        }
+      );
+    });
+    </script>';
+  }
+
+  public static function smartSnackbar($msgs, $timeout = 10000, $printHTML = true) {
+    global $_GET;
+
+    if (!isset($_GET["msg"])) return;
+
+    foreach ($msgs as $msg) {
+      if ($_GET["msg"] == $msg[0]) {
+        self::snackbar($msg[1], $timeout, $printHTML);
+        return;
+      }
+    }
+  }
+
+  public static function debugJson($array) {
+    return security::htmlsafe(json_encode($array, JSON_PRETTY_PRINT));
+  }
+
+  public static function includeHead() {
+    include("includes/head.php");
+  }
+
+  public static function includeNav() {
+    global $conf, $mdHeaderRowMore, $mdHeaderMore, $mdHeaderRowBefore;
+
+    $activeView = security::getActiveView();
+    switch ($activeView) {
+      case self::VIEW_ADMIN:
+      include("includes/adminnav.php");
+      break;
+
+      case self::VIEW_WORKER:
+      include("includes/workernav.php");
+      break;
+
+      default:
+      exit();
+    }
+  }
+
+  public static function backBtn($url) {
+    return '<a class="backbtn mdl-button mdl-js-button mdl-button--icon mdl-js-ripple-effect" href="'.$url.'"><i id="auto_backbtn" class="material-icons">arrow_back</i></a><div class="mdl-tooltip" for="auto_backbtn">Atrás</div><div style="width: 16px;"></div>';
+  }
+
+  public static function printDebug($function, $return, $always=false, $notjson=false) {
+    global $conf;
+
+    if ($always || $conf["debug"])
+      echo '<details class="debug margintop">
+        <summary>Debug:</summary>
+        <p><b>'.security::htmlsafe($function).'</b></p>
+        <div class="overflow-wrapper"><pre>'.($notjson ? security::htmlsafe(print_r($return, true)) : self::debugJson($return)).'</pre></div>
+      </details>';
+  }
+
+  public static function renderPagination($rows, $page, $limit = 10, $showLimitLink = false, $alreadyHasParameters = false, $limitChange = false, $highlightedPage = false) {
+    global $_GET;
+
+    $numPages = ($limit == 0 ? 1 : ceil($rows/$limit));
+    if ($numPages > 1) {
+      $currentPage = ((isset($_GET["page"]) && $_GET["page"] <= $numPages && $_GET["page"] >= 1) ? $_GET["page"] : 1);
+
+      echo '<div class="pagination">';
+      for ($i = 1; $i <= $numPages; $i++) {
+        echo ($i != $currentPage ? '<a class="page'.($i == $highlightedPage ? " mdl-color-text--green" : "").'" href="'.security::htmlsafe($page).($alreadyHasParameters ? "&" : "?").'page='.(int)$i.($showLimitLink ? '&limit='.(int)$limit : '').'">'.(int)$i.'</a> ' : '<b class="page">'.(int)$i.'</b> ');
+      }
+      echo '</div>';
+    }
+
+    if ($limitChange !== false) {
+      ?>
+      <div class="limit-change-container">Ver <select id="limit-change">
+        <?php
+        if (isset($limitChange["options"])) {
+          if (!in_array($limit, $limitChange["options"])) {
+            echo "<option value=\"".(int)$limit."\" selected>".(int)$limit."</option>";
+          }
+          foreach ($limitChange["options"] as $option) {
+            echo "<option value=\"".(int)$option."\"".($option == $limit ? " selected" : "").">".(int)$option."</option>";
+          }
+        }
+        ?>
+      </select> <?=security::htmlsafe($limitChange["elementName"])?> por página.</div>
+      <?php
+    }
+  }
+
+  public static function padNum($num, $length) {
+    return str_pad($num, $length, "0", STR_PAD_LEFT);
+  }
+
+  public static function isMDColor() {
+    global $conf;
+
+    return (($conf["backgroundColor"][0] ?? "") != "#");
+  }
+
+  public static function printBodyTag() {
+    global $conf;
+
+    $conf["backgroundColorIsDark"];
+    echo "<body ".(!visual::isMDColor() ? "style=\"background-color: ".security::htmlsafe($conf["backgroundColor"]).";\"" : "")."class=\"".(visual::isMDColor() ? "mdl-color--".security::htmlsafe($conf["backgroundColor"]) : "").($conf["backgroundColorIsDark"] ? " dark-background" : "")."\">";
+  }
+
+  // WARNING: We will not sanitize $msg, so sanitize it before calling this function!
+  public static function addTooltip($id, $msg) {
+    global $_tooltips;
+
+    if (!isset($_tooltips)) $_tooltips = "";
+    $_tooltips .= '<div class="mdl-tooltip" for="'.security::htmlsafe($id).'">'.$msg.'</div>';
+  }
+
+  public static function renderTooltips() {
+    global $_tooltips;
+
+    echo ($_tooltips ?? "");
+  }
+
+  private static function addMsgToUrl($url, $msg = false) {
+    if ($msg === false) return $url;
+    return $url.(preg_match("/\?/", $url) == 1 ? "&" : "?")."msg=".urlencode($msg);
+  }
+
+  public static function getContinueUrl($defaultUrl, $msg = false, $method = "GET") {
+    global $_GET, $_POST;
+
+    $url = "";
+
+    switch ($method) {
+      case "GET":
+      if (!isset($_GET["continue"])) return self::addMsgToUrl($defaultUrl, $msg);
+      $url = (string)$_GET["continue"];
+      break;
+
+      case "POST":
+      if (!isset($_POST["continue"])) return self::addMsgToUrl($defaultUrl, $msg);
+      $url = (string)$_POST["continue"];
+      break;
+
+      default:
+      return self::addMsgToUrl($defaultUrl, $msg);
+    }
+
+    if (!preg_match("/^[^\/\\\\]*$/", $url)) return self::addMsgToUrl($defaultUrl, $msg);
+
+    if ($msg !== false) $url = self::addMsgToUrl($url, $msg);
+
+    return $url;
+  }
+
+  public static function addContinueInput($url = false) {
+    global $_GET, $_POST;
+
+    if ($url === false) {
+      if (isset($_GET["continue"])) $url = $_GET["continue"];
+      elseif (isset($_POST["continue"])) $url = $_POST["continue"];
+      else return;
+    }
+
+    echo '<input type="hidden" name="continue" value="'.security::htmlsafe($url).'">';
+  }
+}