/*
Theme Name: BrightTech Learn
Description: A fast, Elementor-ready theme for online technology learning. Blueprint-paper look with light and dark modes, self-hosted fonts (no Google Fonts requests), copy buttons on code blocks, reading time and progress on articles, and slots for Polylang or WPML language switchers.
Version: 1.0.0
Requires at least: 6.3
Requires PHP: 7.4
License: GNU General Public License v2 or later
License URI: https://www.gnu.org/licenses/gpl-2.0.html
Text Domain: brighttech-learn
Tags: blog, education, custom-logo, custom-menu, featured-images, translation-ready, threaded-comments, wide-blocks
*/

/* ---------- Fonts (self-hosted, IBM Plex, SIL OFL) ---------- */
@font-face{font-family:"IBM Plex Sans";font-style:normal;font-weight:400;font-display:swap;src:url(assets/fonts/ibm-plex-sans-latin-400-normal.woff2) format("woff2")}
@font-face{font-family:"IBM Plex Sans";font-style:italic;font-weight:400;font-display:swap;src:url(assets/fonts/ibm-plex-sans-latin-400-italic.woff2) format("woff2")}
@font-face{font-family:"IBM Plex Sans";font-style:normal;font-weight:600;font-display:swap;src:url(assets/fonts/ibm-plex-sans-latin-600-normal.woff2) format("woff2")}
@font-face{font-family:"IBM Plex Sans Condensed";font-style:normal;font-weight:700;font-display:swap;src:url(assets/fonts/ibm-plex-sans-condensed-latin-700-normal.woff2) format("woff2")}
@font-face{font-family:"IBM Plex Mono";font-style:normal;font-weight:400;font-display:swap;src:url(assets/fonts/ibm-plex-mono-latin-400-normal.woff2) format("woff2")}
@font-face{font-family:"IBM Plex Mono";font-style:normal;font-weight:500;font-display:swap;src:url(assets/fonts/ibm-plex-mono-latin-500-normal.woff2) format("woff2")}

/* ---------- Tokens ---------- */
:root{
  color-scheme:light;
  --paper:#F2F5FA; --sheet:#FFFFFF; --sheet-2:#E8EDF6;
  --ink:#0F1E3A; --muted:#4B5B78; --rule:#B9C6DD;
  --cobalt:#2250F5; --on-cobalt:#FFFFFF; --link:#1B45D6;
  --redline:#E4431B; --redline-text:#B8310F;
  --grid:rgba(34,80,245,.08);
  --code-bg:#0B1B3C; --code-ink:#E6EEFF;
  --font-ui:"IBM Plex Sans",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --font-display:"IBM Plex Sans Condensed","IBM Plex Sans",system-ui,sans-serif;
  --font-mono:"IBM Plex Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --wide:1160px; --read:780px; --gutter:clamp(1rem,4vw,2rem);
  --r-sm:3px; --r-md:8px; --cell:1.5px solid var(--rule);
}
[data-theme="dark"]{
  color-scheme:dark;
  --paper:#0B1B3C; --sheet:#10264F; --sheet-2:#0D2147;
  --ink:#E6EEFF; --muted:#A5B6D8; --rule:#2E4577;
  --cobalt:#8FB0FF; --on-cobalt:#0B1B3C; --link:#9DBBFF;
  --redline:#FF7A55; --redline-text:#FF9272;
  --grid:rgba(143,176,255,.09);
  --code-bg:#07122B;
}

/* ---------- Base ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:5rem}
body{
  margin:0;color:var(--ink);background-color:var(--paper);
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);
  background-size:24px 24px;
  font:400 1.0625rem/1.65 var(--font-ui);
  -webkit-font-smoothing:antialiased;
}
img,video,iframe,svg{max-width:100%;height:auto}
a{color:var(--link);text-underline-offset:.18em;text-decoration-thickness:1.5px}
a:hover{color:var(--redline-text)}
:focus-visible{outline:3px solid var(--redline);outline-offset:2px;border-radius:2px}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:700;line-height:1.1;letter-spacing:-.01em;margin:2em 0 .5em;text-wrap:balance}
h1{font-size:clamp(2.4rem,5.5vw,3.75rem);margin-top:0}
h2{font-size:clamp(1.7rem,3.2vw,2.2rem)}
h3{font-size:1.5rem}
h4{font-size:1.2rem}
p,ul,ol,dl,pre,blockquote,table,figure{margin:0 0 1.25em}
hr{border:0;border-top:var(--cell);margin:2.5em 0}
.screen-reader-text{position:absolute!important;width:1px;height:1px;margin:-1px;padding:0;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.skip-link:focus{position:fixed!important;top:.75rem;left:.75rem;width:auto;height:auto;margin:0;padding:.6rem 1rem;clip:auto;background:var(--cobalt);color:var(--on-cobalt);z-index:1000;border-radius:var(--r-sm)}
.btl-wrap{max-width:var(--wide);margin:0 auto;padding:clamp(2rem,6vw,4rem) var(--gutter)}

/* ---------- Buttons and forms ---------- */
.btl-btn,.wp-block-button__link,input[type=submit],button[type=submit]{
  display:inline-block;padding:.7rem 1.2rem;border:1.5px solid var(--cobalt);border-radius:var(--r-md);
  background:var(--cobalt);color:var(--on-cobalt);font:600 1rem/1.2 var(--font-ui);text-decoration:none;cursor:pointer}
.btl-btn:hover,.wp-block-button__link:hover,input[type=submit]:hover,button[type=submit]:hover{background:transparent;color:var(--link)}
input[type=text],input[type=email],input[type=url],input[type=search],input[type=password],textarea,select{
  width:100%;padding:.7rem .85rem;border:1.5px solid var(--rule);border-radius:var(--r-md);background:var(--sheet);color:var(--ink);font:inherit}
input:focus,textarea:focus,select:focus{border-color:var(--cobalt);outline:3px solid color-mix(in srgb,var(--cobalt) 35%,transparent);outline-offset:0}
.btl-search{display:flex;gap:.5rem;max-width:34rem}
.btl-search input[type=search]{flex:1}

/* ---------- Header ---------- */
.btl-header{position:sticky;top:0;z-index:50;background:var(--paper);border-bottom:2px solid var(--ink)}
.btl-header__inner{max-width:var(--wide);margin:0 auto;padding:.6rem var(--gutter);display:flex;align-items:center;gap:1.25rem;flex-wrap:wrap}
.btl-brand{margin-right:auto}
.btl-brand a{color:var(--ink);text-decoration:none;font:700 1.6rem/1 var(--font-display);letter-spacing:-.01em}
.btl-brand img{display:block;max-height:44px;width:auto}
.btl-menu,.btl-menu ul{list-style:none;margin:0;padding:0}
.btl-menu{display:flex;gap:.25rem;flex-wrap:wrap}
.btl-menu a{display:block;padding:.5rem .75rem;color:var(--ink);text-decoration:none;font-weight:600;font-size:.97rem;border-bottom:2px solid transparent}
.btl-menu a:hover,.btl-menu .current-menu-item>a,.btl-menu .current-menu-ancestor>a{border-bottom-color:var(--redline);color:var(--ink)}
.btl-menu li{position:relative}
.btl-menu .sub-menu{display:none;position:absolute;left:0;top:100%;min-width:14rem;background:var(--sheet);border:var(--cell);border-radius:var(--r-md);padding:.35rem;z-index:5}
.btl-menu li:hover>.sub-menu,.btl-menu li:focus-within>.sub-menu{display:block}
.btl-tools{display:flex;align-items:center;gap:.75rem}
.btl-lang{display:flex;gap:.25rem;list-style:none;margin:0;padding:0}
.btl-lang a{display:block;padding:.3rem .55rem;border:var(--cell);border-radius:var(--r-sm);color:var(--ink);text-decoration:none;font:500 .85rem var(--font-mono)}
.btl-lang .current-lang a{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.btl-themetoggle,.btl-navtoggle{display:inline-flex;align-items:center;gap:.4rem;padding:.45rem .6rem;border:var(--cell);border-radius:var(--r-md);background:var(--sheet);color:var(--ink);font:600 .95rem var(--font-ui);cursor:pointer}
.btl-themetoggle:hover,.btl-navtoggle:hover{border-color:var(--cobalt)}
.btl-navtoggle{display:none}
@media (max-width:820px){
  .btl-navtoggle{display:inline-flex}
  .btl-nav{display:none;order:5;flex-basis:100%}
  .btl-nav.is-open{display:block}
  .btl-menu{flex-direction:column}
  .btl-menu .sub-menu{display:block;position:static;border:0;padding:0 0 0 1rem;background:transparent}
}

/* ---------- Page head and card grid ---------- */
.btl-pagehead{margin-bottom:2.5rem}
.btl-pagehead__title{max-width:18ch}
.btl-pagehead__desc{max-width:60ch;color:var(--muted);font-size:1.15rem}
.btl-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,19rem),1fr));gap:1.5rem}
.btl-card{display:flex;flex-direction:column;background:var(--sheet);border:1.5px solid var(--ink);border-radius:var(--r-md);overflow:hidden}
.btl-card:hover{border-color:var(--cobalt)}
.btl-card__media{display:block;border-bottom:1.5px solid var(--ink);aspect-ratio:16/10;overflow:hidden;background:var(--sheet-2)}
.btl-card__media img{width:100%;height:100%;object-fit:cover;display:block}
.btl-card__body{padding:1.1rem 1.2rem .6rem;flex:1}
.btl-card__title{font-size:1.5rem;margin:0 0 .5rem}
.btl-card__title a{color:var(--ink);text-decoration:none}
.btl-card__title a:hover{color:var(--link);text-decoration:underline}
.btl-card__excerpt{margin:0;color:var(--muted);font-size:.98rem}

/* Title-block strip: cells of labelled facts, like a drawing's title block */
.btl-strip,.btl-titleblock{display:grid;grid-auto-flow:column;grid-auto-columns:1fr;margin:0}
.btl-strip>div,.btl-titleblock>div{padding:.55rem 1.2rem;border-left:var(--cell);min-width:0}
.btl-strip>div:first-child,.btl-titleblock>div:first-child{border-left:0}
.btl-strip{border-top:1.5px solid var(--ink);margin-top:1rem}
.btl-strip dd,.btl-titleblock dd{margin:0;font:500 .86rem/1.35 var(--font-mono);overflow-wrap:anywhere}
.btl-titleblock dt{font:600 .78rem/1.2 var(--font-ui);color:var(--muted);margin-bottom:.15rem}
.btl-titleblock dd a{color:var(--ink)}
.btl-pagination,.navigation.pagination{margin-top:2.5rem}
.nav-links{display:flex;gap:.5rem;flex-wrap:wrap}
.page-numbers{padding:.45rem .8rem;border:var(--cell);border-radius:var(--r-sm);background:var(--sheet);color:var(--ink);text-decoration:none;font:500 .95rem var(--font-mono)}
.page-numbers.current{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.btl-empty{font-size:1.15rem;max-width:44ch}

/* ---------- Article ---------- */
.btl-progress{position:fixed;top:0;left:0;right:0;height:4px;z-index:60;pointer-events:none}
.btl-progress span{display:block;height:100%;background:var(--redline);transform-origin:0 50%;transform:scaleX(0)}
.btl-article{max-width:var(--read);margin:clamp(1.5rem,5vw,3.5rem) auto;background:var(--sheet);border:1.5px solid var(--ink);border-radius:var(--r-md);overflow:hidden}
.btl-article__head{padding:clamp(1.5rem,5vw,3rem) clamp(1.25rem,5vw,3rem) 0}
.btl-article__title{font-size:clamp(2.2rem,5vw,3.4rem)}
.btl-article .btl-titleblock{border:var(--cell);border-radius:var(--r-sm);background:var(--sheet-2);grid-auto-flow:row;grid-template-columns:repeat(auto-fit,minmax(9rem,1fr))}
.btl-article .btl-titleblock>div{border-left:0;border-top:var(--cell)}
.btl-article .btl-titleblock>div:nth-child(-n+2){border-top:0}
.btl-article__image{margin:1.75rem 0 0;border-block:1.5px solid var(--ink)}
.btl-article__image img{display:block;width:100%}
.btl-prose{padding:clamp(1.5rem,5vw,3rem)}
.btl-prose>*:last-child{margin-bottom:0}
.btl-prose a{font-weight:600}
.btl-prose h2{padding-top:.4em;border-top:var(--cell)}
.btl-prose blockquote{margin-inline:0;padding:.25rem 0 .25rem 1.25rem;border-left:4px solid var(--redline);color:var(--muted);font-style:italic}
.btl-prose img{border-radius:var(--r-sm)}
.btl-prose figcaption{color:var(--muted);font-size:.88rem;margin-top:.4rem}
.btl-prose table{width:100%;border-collapse:collapse;display:block;overflow-x:auto}
.btl-prose th,.btl-prose td{padding:.55rem .8rem;border:var(--cell);text-align:left}
.btl-prose th{background:var(--sheet-2);font-weight:600}
.btl-prose li+li{margin-top:.3em}
.btl-prose .alignwide{margin-inline:calc(-1 * clamp(0rem,3vw,2rem))}
.btl-article__foot{padding:0 clamp(1.5rem,5vw,3rem) clamp(1.5rem,5vw,3rem)}
.btl-tags a{display:inline-block;margin:0 .35rem .35rem 0;padding:.2rem .6rem;border:var(--cell);border-radius:var(--r-sm);color:var(--ink);text-decoration:none;font:500 .85rem var(--font-mono)}
.btl-tags a:hover{border-color:var(--cobalt)}
.post-navigation .nav-links{display:grid;grid-template-columns:1fr 1fr;gap:1rem}
.post-navigation a{display:block;padding:.9rem 1rem;border:var(--cell);border-radius:var(--r-md);color:var(--ink);text-decoration:none;font-weight:600}
.post-navigation a:hover{border-color:var(--cobalt)}
.post-navigation .nav-next{text-align:right}
.post-navigation small{display:block;color:var(--muted);font-weight:400}

/* Code: the one place the page goes full ink */
code,kbd,samp{font-family:var(--font-mono);font-size:.9em}
:not(pre)>code{padding:.12em .38em;border-radius:var(--r-sm);background:var(--sheet-2);border:1px solid var(--rule)}
pre{position:relative;margin-inline:0;padding:1.1rem 1.25rem;overflow:auto;background:var(--code-bg);color:var(--code-ink);border-left:4px solid var(--redline);border-radius:var(--r-sm);font:400 .9rem/1.6 var(--font-mono);tab-size:2}
pre code{font:inherit;background:none;border:0;padding:0;color:inherit}
.btl-codewrap{position:relative;margin-bottom:1.25em}
.btl-codewrap pre{margin:0;padding-top:2.6rem}
.btl-copy{position:absolute;top:.5rem;right:.5rem;z-index:2;padding:.25rem .65rem;border:1px solid rgba(230,238,255,.35);border-radius:var(--r-sm);background:transparent;color:#E6EEFF;font:500 .8rem var(--font-mono);cursor:pointer}
.btl-copy:hover{background:rgba(230,238,255,.12)}
.btl-copy.is-copied{background:#E6EEFF;color:#0B1B3C}

/* ---------- Comments ---------- */
.btl-comments{margin-top:2.5rem}
.btl-comment-list,.btl-comment-list .children{list-style:none;margin:0;padding:0}
.btl-comment-list .children{margin-left:1.5rem;border-left:var(--cell);padding-left:1rem}
.btl-comment-list .comment-body{padding:1rem 0;border-top:var(--cell)}
.comment-form label{display:block;font-weight:600;margin-bottom:.25rem}

/* ---------- Footer: a drawing title block ---------- */
.btl-footer{margin-top:3rem;border-top:2px solid var(--ink);background:var(--paper)}
.btl-footer__widgets{max-width:var(--wide);margin:0 auto;padding:2rem var(--gutter) 0;display:grid;grid-template-columns:repeat(auto-fit,minmax(14rem,1fr));gap:1.5rem}
.widget-title{font:700 1.2rem var(--font-display);margin:0 0 .5rem}
.btl-footer .btl-titleblock{max-width:var(--wide);margin:2rem auto;border:1.5px solid var(--ink);background:var(--sheet);width:calc(100% - 2 * var(--gutter));grid-auto-flow:row;grid-template-columns:2fr 1.5fr 1fr}
.btl-footer .btl-titleblock>div{padding:1rem 1.25rem}
.btl-footer .btl-titleblock strong{display:block;font:700 1.4rem/1.1 var(--font-display)}
.btl-footer .btl-titleblock p{margin:.35rem 0 0;color:var(--muted);font-size:.95rem}
.btl-footer__menu{list-style:none;margin:0;padding:0}
.btl-footer__menu a{color:var(--ink);text-decoration:none;font-weight:600;display:inline-block;padding:.15rem 0}
.btl-footer__menu a:hover{color:var(--redline-text);text-decoration:underline}
.btl-footer__legal{font:500 .85rem var(--font-mono);color:var(--muted)}
@media (max-width:820px){
  .btl-footer .btl-titleblock{grid-template-columns:1fr}
  .btl-footer .btl-titleblock>div{border-left:0;border-top:var(--cell)}
  .btl-footer .btl-titleblock>div:first-child{border-top:0}
  .btl-strip{grid-auto-flow:row}
  .btl-strip>div{border-left:0;border-top:var(--cell)}
  .btl-strip>div:first-child{border-top:0}
  .post-navigation .nav-links{grid-template-columns:1fr}
}

/* ---------- Helpers for Elementor sections ---------- */
.bt-sheet{background:var(--sheet);border:1.5px solid var(--ink);border-radius:var(--r-md)}
.bt-sheet-2{background:var(--sheet-2)}
.bt-on-grid{background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:24px 24px}
.bt-code{font-family:var(--font-mono)}
.bt-redline{border-left:4px solid var(--redline);padding-left:1rem}

@media (prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
.wp-caption,.wp-block-image{max-width:100%}
.alignleft{float:left;margin:0 1.25rem 1rem 0}.alignright{float:right;margin:0 0 1rem 1.25rem}.aligncenter{display:block;margin-inline:auto}
.sticky .btl-card__title::before{content:"\2605\00a0"}
.bypostauthor{}.gallery-caption{}