diff --git a/_javascript/utils/smooth-scroll.js b/_javascript/utils/smooth-scroll.js
index 8869da6..6ddf96d 100644
--- a/_javascript/utils/smooth-scroll.js
+++ b/_javascript/utils/smooth-scroll.js
@@ -8,7 +8,6 @@
 */
 
 $(function() {
-  const REM = 16; /* 16px */
   const $topbarTitle = $("#topbar-title");
   const topbarHeight = $("#topbar-wrapper").outerHeight();
   const SCROLL_MARK = "scroll-focus";
@@ -40,27 +39,15 @@ $(function() {
             let destOffset = $target.offset().top;
 
             if (destOffset < curOffset) { // scroll up
-              if (toFootnoteRef) {
-                // Avoid the top-bar covering `fnref` when scrolling up
-                // because `fnref` has no `%anchor`(see: module.scss) style.
-                destOffset -= (topbarHeight + REM / 2);
-              }
-
-              if (isAnchor && $topbarTitle.is(":hidden")) {
-                destOffset += topbarHeight;
-              }
-
-            } else { // scroll down
-              if (!isAnchor && !toFootnote) { // the ToC item
-                destOffset += topbarHeight;
+              if (!isAnchor && !toFootnote && $topbarTitle.is(":hidden")) { // the ToC item
+                destOffset -= topbarHeight;
               }
             }
 
             $("html,body").animate({
               scrollTop: destOffset
-            }, 800, () => {
 
-              // const $target = $($target);
+            }, 800, () => {
               $target.focus();
 
               /* clean up old scroll mark */
diff --git a/_sass/addon/module.scss b/_sass/addon/module.scss
index 7e25531..da4bf1e 100644
--- a/_sass/addon/module.scss
+++ b/_sass/addon/module.scss
@@ -11,12 +11,9 @@
 }
 
 %section {
-  padding-top: 3.5rem;
-  margin-top: -2.5rem;
-
   #core-wrapper & {
-    line-height: 1.2;
-    margin-bottom: 1rem;
+    margin-top: 2.5rem;
+    margin-bottom: 2rem;
   }
 }
 
@@ -24,7 +21,7 @@
   > a {
     font-size: 70%;
     visibility: hidden;
-    margin-left: 0.25rem;
+    margin-left: 0.5rem;
     border-bottom: none !important;
     opacity: 0;
     transition: opacity 0.25s ease-in, visibility 0s ease-in 0.25s;
diff --git a/assets/js/dist/post.min.js b/assets/js/dist/post.min.js
index fd572de..f4a3e81 100644
--- a/assets/js/dist/post.min.js
+++ b/assets/js/dist/post.min.js
@@ -3,4 +3,4 @@
  * © 2019 Cotes Chung
  * MIT Licensed
  */
-$(function(){$(window).scroll(()=>{50<$(this).scrollTop()&&"none"===$("#sidebar-trigger").css("display")?$("#back-to-top").fadeIn():$("#back-to-top").fadeOut()}),$("#back-to-top").click(()=>($("body,html").animate({scrollTop:0},800),!1))}),$(function(){$(".mode-toggle").click(t=>{const e=$(t.target);let o=e.prop("tagName")==="button".toUpperCase()?e:e.parent();o.blur(),flipMode()})}),$(function(){const t=$("#sidebar-trigger"),e=$("#search-trigger"),o=$("#search-cancel"),a=$("#search-cleaner"),n=$("#main"),l=$("#topbar-title"),r=$("#search-wrapper"),s=$("#search-result-wrapper"),i=$("#search-results"),c=$("#search-input"),d=$("#search-hints"),u=function(){let t=0;return{block(){t=window.scrollY,$("html,body").scrollTop(0)},release(){$("html,body").scrollTop(t)},getOffset(){return t}}}(),p={on(){t.addClass("unloaded"),l.addClass("unloaded"),e.addClass("unloaded"),r.addClass("d-flex"),o.addClass("loaded")},off(){o.removeClass("loaded"),r.removeClass("d-flex"),t.removeClass("unloaded"),l.removeClass("unloaded"),e.removeClass("unloaded")}},h=function(){let t=!1;return{on(){t||(u.block(),s.removeClass("unloaded"),n.addClass("unloaded"),t=!0)},off(){t&&(i.empty(),d.hasClass("unloaded")&&d.removeClass("unloaded"),s.addClass("unloaded"),a.removeClass("visible"),n.removeClass("unloaded"),u.release(),c.val(""),t=!1)},isVisible(){return t}}}();function f(){return o.hasClass("loaded")}e.click(function(){p.on(),h.on(),c.focus()}),o.click(function(){p.off(),h.off()}),c.focus(function(){r.addClass("input-focus")}),c.focusout(function(){r.removeClass("input-focus")}),c.on("keyup",function(t){8===t.keyCode&&""===c.val()?f()?d.removeClass("unloaded"):h.off():""!==c.val()&&(h.on(),a.hasClass("visible")||a.addClass("visible"),f()&&d.addClass("unloaded"))}),a.on("click",function(){c.val(""),f()?(d.removeClass("unloaded"),i.empty()):h.off(),c.focus(),a.removeClass("visible")})}),$(function(){var t=function(){const t="sidebar-display";let e=!1;const o=$("body");return{toggle(){!1===e?o.attr(t,""):o.removeAttr(t),e=!e}}}();$("#sidebar-trigger").click(t.toggle),$("#mask").click(t.toggle)}),$(function(){$('[data-toggle="tooltip"]').tooltip()}),$(function(){const e=$("#topbar-wrapper"),o=$("#toc-wrapper"),a=$(".access"),n=$("#search-input");let l,r=0;const s=e.outerHeight();$(window).scroll(function(t){$("#topbar-title").is(":hidden")&&(l=!0)}),setInterval(function(){l&&(function(){var t=$(this).scrollTop();Math.abs(r-t)<=5||(t>r&&t>s?(e.removeClass("topbar-down").addClass("topbar-up"),0<o.length&&o.removeClass("topbar-down"),0<a.length&&a.removeClass("topbar-down"),n.is(":focus")&&n.blur()):t+$(window).height()<$(document).height()&&(e.removeClass("topbar-up").addClass("topbar-down"),0<o.length&&o.addClass("topbar-down"),0<a.length&&a.addClass("topbar-down")),r=t)}(),l=!1)},250)}),$(function(){const t=$("#topbar-title"),e=$("div.post>h1"),o=t.text().trim();let a=(0<e.length?e:$("h1")).text().trim();($("#page-category").length||$("#page-tag").length)&&/\s/.test(a)&&(a=a.replace(/[0-9]/g,"").trim()),$(window).scroll(function(){return!($("#post-list").length||e.is(":hidden")||t.is(":hidden")||$("#sidebar.sidebar-expand").length)&&void(95<=$(this).scrollTop()?t.text()!==a&&t.text(a):t.text()!==o&&t.text(o))}),t.click(function(){$("body,html").animate({scrollTop:0},800)})}),$(function(){var t="#main > div.row:first-child > div:first-child";if(!($(t+" img").length<=0)){var e=document.querySelectorAll(t+" img[data-src]");const o=lozad(e);o.observe(),$(t+` p > img[data-src],${t} img[data-src].preview-img`).each(function(){let t=$(this).next();var e="EM"===t.prop("tagName")?t.text():"",o=$(this).attr("data-src");$(this).wrap(`<a href="${o}" title="${e}" class="popup"></a>`)}),$(".popup").magnificPopup({type:"image",closeOnContentClick:!0,showCloseBtn:!1,zoom:{enabled:!0,duration:300,easing:"ease-in-out"}}),$(t+" a").has("img").addClass("img-link")}}),$(function(){let o=$(".timeago").length,t=void 0;const n=$("meta[name=day-prompt]").attr("content"),l=$("meta[name=hour-prompt]").attr("content"),r=$("meta[name=minute-prompt]").attr("content"),s=$("meta[name=justnow-prompt]").attr("content");function e(){return $(".timeago").each(function(){var t,e;!1!==$(this)[0].hasAttribute("date")?(e=function(t,e){let o=new Date,a=new Date(t);return a.getFullYear()!==o.getFullYear()||a.getMonth()!==o.getMonth()?e:(t=Math.floor((o-a)/1e3),1<=(e=Math.floor(t/86400))?` ${e} `+n:1<=(e=Math.floor(t/3600))?` ${e} `+l:1<=(t=Math.floor(t/60))?` ${t} `+r:s)}($(this).attr("date"),t=$(this).text()))===t?$(this).removeAttr("date"):$(this).text(e):--o}),0===o&&void 0!==t&&clearInterval(t),o}0!==o&&0<e()&&(t=setInterval(e,6e4))}),$(function(){$("input[type=checkbox]").addClass("unloaded"),$("input[type=checkbox][checked]").before('<i class="fas fa-check-circle checked"></i>'),$("input[type=checkbox]:not([checked])").before('<i class="far fa-circle"></i>')}),$(function(){var t=".code-header>button";const e="timeout";function n(t){if($(t)[0].hasAttribute(e)){t=$(t).attr(e);if(Number(t)>Date.now())return 1}}function l(t){$(t).attr(e,Date.now()+2e3)}function r(t){$(t).removeAttr(e)}const o=new ClipboardJS(t,{target(t){let e=t.parentNode.nextElementSibling;return e.querySelector("code .rouge-code")}});$(t).tooltip({trigger:"hover",placement:"left"});const a=function(t){let e=$(t).children();return e.attr("class")}(t);o.on("success",t=>{t.clearSelection();const e=t.trigger;var o;n(e)||(function(t){let e=$(t),o=e.children();o.attr("class","fas fa-check")}(e),o=e,t=$(o).attr("title-succeed"),$(o).attr("data-original-title",t).tooltip("show"),l(e),setTimeout(()=>{var t;t=e,$(t).tooltip("hide").removeAttr("data-original-title"),function(t){let e=$(t),o=e.children();o.attr("class",a)}(e),r(e)},2e3))}),$("#copy-link").click(t=>{let e=$(t.target);if(!n(e)){t=window.location.href;const o=$("<input>");$("body").append(o),o.val(t).select(),document.execCommand("copy"),o.remove();const a=e.attr("data-original-title");t=e.attr("title-succeed");e.attr("data-original-title",t).tooltip("show"),l(e),setTimeout(()=>{e.attr("data-original-title",a),r(e)},2e3)}})}),$(function(){const s=$("#topbar-title"),i=$("#topbar-wrapper").outerHeight(),c="scroll-focus";$("a[href*='#']").not("[href='#']").not("[href='#0']").click(function(n){if(this.pathname.replace(/^\//,"")===location.pathname.replace(/^\//,"")&&location.hostname===this.hostname){const r=decodeURI(this.hash);let e=RegExp(/^#fnref:/).test(r),o=!e&&RegExp(/^#fn:/).test(r);var l=r.includes(":")?r.replace(/\:/g,"\\:"):r;let a=$(l);l=$(this).parent().prop("tagName"),l=RegExp(/^H\d/).test(l);if(void 0!==a){n.preventDefault(),history.pushState&&history.pushState(null,null,r);n=l?$(this).offset().top:$(window).scrollTop();let t=a.offset().top;t<n?(e&&(t-=i+8),l&&s.is(":hidden")&&(t+=i)):l||o||(t+=i),$("html,body").animate({scrollTop:t},800,()=>(a.focus(),$(`[${c}=true]`).length&&$(`[${c}=true]`).attr(c,!1),$(":target").length&&$(":target").attr(c,!1),(o||e)&&a.attr(c,!0),a.is(":focus")?!1:(a.attr("tabindex","-1"),void a.focus())))}}})});
\ No newline at end of file
+$(function(){$(window).scroll(()=>{50<$(this).scrollTop()&&"none"===$("#sidebar-trigger").css("display")?$("#back-to-top").fadeIn():$("#back-to-top").fadeOut()}),$("#back-to-top").click(()=>($("body,html").animate({scrollTop:0},800),!1))}),$(function(){$(".mode-toggle").click(t=>{const e=$(t.target);let o=e.prop("tagName")==="button".toUpperCase()?e:e.parent();o.blur(),flipMode()})}),$(function(){const t=$("#sidebar-trigger"),e=$("#search-trigger"),o=$("#search-cancel"),a=$("#search-cleaner"),n=$("#main"),l=$("#topbar-title"),r=$("#search-wrapper"),s=$("#search-result-wrapper"),i=$("#search-results"),c=$("#search-input"),d=$("#search-hints"),u=function(){let t=0;return{block(){t=window.scrollY,$("html,body").scrollTop(0)},release(){$("html,body").scrollTop(t)},getOffset(){return t}}}(),p={on(){t.addClass("unloaded"),l.addClass("unloaded"),e.addClass("unloaded"),r.addClass("d-flex"),o.addClass("loaded")},off(){o.removeClass("loaded"),r.removeClass("d-flex"),t.removeClass("unloaded"),l.removeClass("unloaded"),e.removeClass("unloaded")}},h=function(){let t=!1;return{on(){t||(u.block(),s.removeClass("unloaded"),n.addClass("unloaded"),t=!0)},off(){t&&(i.empty(),d.hasClass("unloaded")&&d.removeClass("unloaded"),s.addClass("unloaded"),a.removeClass("visible"),n.removeClass("unloaded"),u.release(),c.val(""),t=!1)},isVisible(){return t}}}();function f(){return o.hasClass("loaded")}e.click(function(){p.on(),h.on(),c.focus()}),o.click(function(){p.off(),h.off()}),c.focus(function(){r.addClass("input-focus")}),c.focusout(function(){r.removeClass("input-focus")}),c.on("keyup",function(t){8===t.keyCode&&""===c.val()?f()?d.removeClass("unloaded"):h.off():""!==c.val()&&(h.on(),a.hasClass("visible")||a.addClass("visible"),f()&&d.addClass("unloaded"))}),a.on("click",function(){c.val(""),f()?(d.removeClass("unloaded"),i.empty()):h.off(),c.focus(),a.removeClass("visible")})}),$(function(){var t=function(){const t="sidebar-display";let e=!1;const o=$("body");return{toggle(){!1===e?o.attr(t,""):o.removeAttr(t),e=!e}}}();$("#sidebar-trigger").click(t.toggle),$("#mask").click(t.toggle)}),$(function(){$('[data-toggle="tooltip"]').tooltip()}),$(function(){const e=$("#topbar-wrapper"),o=$("#toc-wrapper"),a=$(".access"),n=$("#search-input");let l,r=0;const s=e.outerHeight();$(window).scroll(function(t){$("#topbar-title").is(":hidden")&&(l=!0)}),setInterval(function(){l&&(function(){var t=$(this).scrollTop();Math.abs(r-t)<=5||(t>r&&t>s?(e.removeClass("topbar-down").addClass("topbar-up"),0<o.length&&o.removeClass("topbar-down"),0<a.length&&a.removeClass("topbar-down"),n.is(":focus")&&n.blur()):t+$(window).height()<$(document).height()&&(e.removeClass("topbar-up").addClass("topbar-down"),0<o.length&&o.addClass("topbar-down"),0<a.length&&a.addClass("topbar-down")),r=t)}(),l=!1)},250)}),$(function(){const t=$("#topbar-title"),e=$("div.post>h1"),o=t.text().trim();let a=(0<e.length?e:$("h1")).text().trim();($("#page-category").length||$("#page-tag").length)&&/\s/.test(a)&&(a=a.replace(/[0-9]/g,"").trim()),$(window).scroll(function(){return!($("#post-list").length||e.is(":hidden")||t.is(":hidden")||$("#sidebar.sidebar-expand").length)&&void(95<=$(this).scrollTop()?t.text()!==a&&t.text(a):t.text()!==o&&t.text(o))}),t.click(function(){$("body,html").animate({scrollTop:0},800)})}),$(function(){var t="#main > div.row:first-child > div:first-child";if(!($(t+" img").length<=0)){var e=document.querySelectorAll(t+" img[data-src]");const o=lozad(e);o.observe(),$(t+` p > img[data-src],${t} img[data-src].preview-img`).each(function(){let t=$(this).next();var e="EM"===t.prop("tagName")?t.text():"",o=$(this).attr("data-src");$(this).wrap(`<a href="${o}" title="${e}" class="popup"></a>`)}),$(".popup").magnificPopup({type:"image",closeOnContentClick:!0,showCloseBtn:!1,zoom:{enabled:!0,duration:300,easing:"ease-in-out"}}),$(t+" a").has("img").addClass("img-link")}}),$(function(){let o=$(".timeago").length,t=void 0;const n=$("meta[name=day-prompt]").attr("content"),l=$("meta[name=hour-prompt]").attr("content"),r=$("meta[name=minute-prompt]").attr("content"),s=$("meta[name=justnow-prompt]").attr("content");function e(){return $(".timeago").each(function(){var t,e;!1!==$(this)[0].hasAttribute("date")?(e=function(t,e){let o=new Date,a=new Date(t);return a.getFullYear()!==o.getFullYear()||a.getMonth()!==o.getMonth()?e:(t=Math.floor((o-a)/1e3),1<=(e=Math.floor(t/86400))?` ${e} `+n:1<=(e=Math.floor(t/3600))?` ${e} `+l:1<=(t=Math.floor(t/60))?` ${t} `+r:s)}($(this).attr("date"),t=$(this).text()))===t?$(this).removeAttr("date"):$(this).text(e):--o}),0===o&&void 0!==t&&clearInterval(t),o}0!==o&&0<e()&&(t=setInterval(e,6e4))}),$(function(){$("input[type=checkbox]").addClass("unloaded"),$("input[type=checkbox][checked]").before('<i class="fas fa-check-circle checked"></i>'),$("input[type=checkbox]:not([checked])").before('<i class="far fa-circle"></i>')}),$(function(){var t=".code-header>button";const e="timeout";function n(t){if($(t)[0].hasAttribute(e)){t=$(t).attr(e);if(Number(t)>Date.now())return 1}}function l(t){$(t).attr(e,Date.now()+2e3)}function r(t){$(t).removeAttr(e)}const o=new ClipboardJS(t,{target(t){let e=t.parentNode.nextElementSibling;return e.querySelector("code .rouge-code")}});$(t).tooltip({trigger:"hover",placement:"left"});const a=function(t){let e=$(t).children();return e.attr("class")}(t);o.on("success",t=>{t.clearSelection();const e=t.trigger;var o;n(e)||(function(t){let e=$(t),o=e.children();o.attr("class","fas fa-check")}(e),o=e,t=$(o).attr("title-succeed"),$(o).attr("data-original-title",t).tooltip("show"),l(e),setTimeout(()=>{var t;t=e,$(t).tooltip("hide").removeAttr("data-original-title"),function(t){let e=$(t),o=e.children();o.attr("class",a)}(e),r(e)},2e3))}),$("#copy-link").click(t=>{let e=$(t.target);if(!n(e)){t=window.location.href;const o=$("<input>");$("body").append(o),o.val(t).select(),document.execCommand("copy"),o.remove();const a=e.attr("data-original-title");t=e.attr("title-succeed");e.attr("data-original-title",t).tooltip("show"),l(e),setTimeout(()=>{e.attr("data-original-title",a),r(e)},2e3)}})}),$(function(){const s=$("#topbar-title"),i=$("#topbar-wrapper").outerHeight(),c="scroll-focus";$("a[href*='#']").not("[href='#']").not("[href='#0']").click(function(n){if(this.pathname.replace(/^\//,"")===location.pathname.replace(/^\//,"")&&location.hostname===this.hostname){const r=decodeURI(this.hash);let e=RegExp(/^#fnref:/).test(r),o=!e&&RegExp(/^#fn:/).test(r);var l=r.includes(":")?r.replace(/\:/g,"\\:"):r;let a=$(l);l=$(this).parent().prop("tagName"),l=RegExp(/^H\d/).test(l);if(void 0!==a){n.preventDefault(),history.pushState&&history.pushState(null,null,r);n=l?$(this).offset().top:$(window).scrollTop();let t=a.offset().top;t<n&&(l||o||!s.is(":hidden")||(t-=i)),$("html,body").animate({scrollTop:t},800,()=>(a.focus(),$(`[${c}=true]`).length&&$(`[${c}=true]`).attr(c,!1),$(":target").length&&$(":target").attr(c,!1),(o||e)&&a.attr(c,!0),a.is(":focus")?!1:(a.attr("tabindex","-1"),void a.focus())))}}})});
\ No newline at end of file