@charset "UTF-8";
/* Source callouts and wide figures retain readable space on a phone. */
.prose img{max-width:100%;height:auto}
.prose blockquote{margin:20px 0;padding:15px 16px;background:var(--light);border-left:3px solid var(--accent);border-radius:0 10px 10px 0}
.prose figure{margin:20px 0;max-width:100%;overflow-x:auto}
.prose figure img{display:block;max-width:none;height:auto}
.prose figcaption{font:12px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;color:var(--muted);margin-top:10px}
.katex-display>.katex{width:max-content;min-width:100%}
.skip{transform:translateY(-150%)}.skip:focus{transform:translateY(0)}
:root{--paper:#f4f6f9;--card:#ffffff;--ink:#142033;--muted:#536274;--line:#dde3ec;--accent:#0a5aa6;--accent-mid:#2f7fcf;--light:#e7f0fb;--soft:#eaf1fa;--soft-line:#c9d9ee;--hover-line:#98b4d6;--gold:#f0b23a;--navy:#11263f;--book:#11263f;--danger:#b3382f;--nav-ink:#3d4f66;--deco:#7d90a8;--control-line:#7f90a6;--track:#e3e9f1;--shelf:#d5dce7;--line-strong:#b8c4d4;--focus:#0a5aa6;--body-size:17px;color-scheme:light;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none;line-height:1.5}
*{box-sizing:border-box}body{margin:0}button,input,select,textarea{font:inherit}button,a,input,textarea,select{-webkit-tap-highlight-color:transparent}a{color:var(--accent);text-decoration:none}button{cursor:pointer}button:disabled{cursor:wait;opacity:.58}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--focus);outline-offset:3px}button,input,textarea,select{border-radius:11px}input,select,textarea{background:var(--card);color:var(--ink);border:1px solid var(--control-line);padding:11px 13px;min-height:46px;max-width:100%}textarea{width:100%;resize:vertical;min-height:190px;line-height:1.7}input[type=checkbox]{accent-color:var(--accent);min-height:20px;width:19px;height:19px;flex-shrink:0}label{display:block}h1,h2,h3,p{margin-top:0}h1,h2,h3{font-weight:680;letter-spacing:-.035em;line-height:1.2}h1{font-size:clamp(29px,3.1vw,43px);max-width:900px;margin-bottom:14px}h2{font-size:25px}h3{font-size:19px}p{margin-bottom:16px}small{font-size:12px}.tiny,.eyebrow,.nav-caption{font-size:12px;font-weight:750;letter-spacing:.09em}.eyebrow{color:var(--accent);display:block;margin-bottom:13px}.muted{color:var(--muted)}.small{font-size:13px}.serif{font-family:Georgia,"Times New Roman",serif}.skip{position:fixed;left:12px;top:-60px;background:var(--navy);color:white;padding:15px;z-index:99}.skip:focus{top:10px}.sidebar{position:fixed;inset:0 auto 0 0;width:250px;padding:31px 23px;background:var(--card);border-right:1px solid var(--line);display:flex;flex-direction:column;z-index:20}.brand{display:flex;gap:10px;align-items:center;color:var(--ink);font-size:23px;font-weight:800;letter-spacing:-.05em;white-space:nowrap}.brand-mark{background:var(--navy);color:var(--gold);width:39px;height:44px;display:grid;place-items:center;border-radius:11px;font:33px Georgia,serif}.brand small{font-size:12px;color:var(--muted);display:block;letter-spacing:0;font-weight:500;margin-top:2px}.nav-caption{color:var(--muted);font-size:12px;margin-top:51px;margin-bottom:16px}.desktop-nav{display:grid;gap:7px}.desktop-nav a{display:flex;gap:14px;align-items:center;min-height:48px;padding:12px 13px;color:var(--nav-ink);font-size:14px;font-weight:550;border-radius:11px}.desktop-nav a span{font-size:23px;width:22px;text-align:center;font-weight:400;line-height:1}.desktop-nav a.active{background:var(--light);color:var(--accent)}.desktop-nav a:hover{background:var(--paper)}.side-note{margin-top:auto;padding:24px 14px 17px;border-top:1px solid var(--line);color:var(--muted)}.side-note .tiny{font-size:12px;letter-spacing:.08em;color:var(--accent)}.side-note p{font-family:Georgia,serif;font-size:19px;color:var(--ink);line-height:1.5;margin:15px 0}.side-equation{display:block;font:21px Georgia,serif;color:var(--muted);letter-spacing:.08em}.side-footer{font-size:12px;color:var(--muted);line-height:1.8;padding:14px}.workspace{margin-left:250px}.topbar{background:var(--paper);height:82px;padding:0 44px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:12px}.breadcrumb{font-size:13px;color:var(--muted)}.offline-badge{display:flex;gap:7px;align-items:center;font-size:12px;color:var(--accent);border:1px solid var(--soft-line);border-radius:99px;padding:7px 11px;white-space:nowrap}.offline-badge i{display:block;width:6px;height:6px;border-radius:50%;background:var(--accent-mid)}.mobile-brand,.bottom-nav{display:none}main{max-width:1320px;margin:auto;padding:39px 44px 35px;min-height:calc(100vh - 150px)}.page-footer{padding:18px 44px 25px;font-size:12px;color:var(--muted);display:flex;justify-content:space-between;gap:20px;border-top:1px solid var(--line)}.intro{margin-bottom:30px}.intro p{color:var(--muted);font-size:15px;max-width:700px;margin-bottom:0}.page-heading{display:flex;justify-content:space-between;gap:20px;align-items:end;margin-bottom:24px}.page-heading h2{margin:0}.page-heading p{margin:8px 0 0}.btn{min-height:45px;display:inline-flex;align-items:center;justify-content:center;gap:9px;padding:11px 18px;background:var(--accent);color:white;border:1px solid var(--accent);border-radius:10px;font-size:13px;font-weight:650;text-align:center;line-height:1.4}.btn:hover{filter:brightness(.94)}.btn.secondary{background:var(--card);border-color:var(--line-strong);color:var(--ink)}.btn.ghost{background:transparent;border-color:transparent;color:var(--accent);padding-left:0}.btn.gold{background:var(--gold);color:var(--navy);border-color:var(--gold)}.btn.danger{background:transparent;border-color:#e1bbb7;color:var(--danger)}.btn.sm{font-size:12px;padding:8px 12px;min-height:40px}.btn.wide{width:100%}.button-row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}.card{background:var(--card);border:1px solid var(--line);border-radius:17px;padding:25px}.hero-grid{display:grid;grid-template-columns:minmax(280px,1.08fr) minmax(250px,1fr);gap:24px;margin-bottom:36px}.book-card{min-height:382px;background:var(--book);color:#f6f8fb;position:relative;padding:32px 33px;border-radius:17px;overflow:hidden;display:flex;flex-direction:column;box-shadow:0 8px 0 -3px var(--shelf),0 14px 30px -15px #1f355044}.book-card:before{content:"";position:absolute;inset:0 auto 0 12px;border-left:1px solid #ffffff14}.book-card .eyebrow{font-size:12px;letter-spacing:.15em;color:#a9c4e4;margin-bottom:27px}.book-card h2{font-family:Georgia,"Times New Roman",serif;font-size:clamp(32px,3vw,46px);font-weight:400;line-height:1.13;max-width:280px;letter-spacing:-.03em;z-index:1;margin-bottom:20px}.book-card .book-subtitle{font-size:12px;color:#b9d0ea;z-index:1}.book-card .book-bottom{display:flex;align-items:end;justify-content:space-between;gap:12px;margin-top:auto;z-index:1;padding-top:35px}.book-author{font-size:12px}.book-author small{color:#9fbddf;display:block;font-size:12px;letter-spacing:.15em;margin-bottom:7px}.book-number{position:absolute;bottom:58px;right:24px;font-family:Georgia,serif;font-size:170px;line-height:1;color:#7aa9d815;font-weight:400}.book-lines{position:absolute;width:250px;height:250px;border:1px solid #d4bd7629;border-radius:50%;right:-83px;top:40px}.book-lines:before,.book-lines:after{content:"";position:absolute;inset:18px;border:1px solid #d4bd7629;border-radius:50%}.book-lines:after{inset:40px}.learning-panel{display:flex;flex-direction:column;gap:18px}.reading-card{flex:1;padding:26px}.reading-card h3{font-size:24px;max-width:300px;line-height:1.3;margin:13px 0}.reading-card p{font-size:13px;color:var(--muted);margin-bottom:23px}.reading-label{font-size:12px;color:var(--accent);font-weight:750;letter-spacing:.08em;display:flex;justify-content:space-between}.progress-bar{height:5px;border-radius:9px;background:var(--track);overflow:hidden;margin:15px 0 11px}.progress-bar i{display:block;background:var(--accent-mid);height:100%;border-radius:9px}.stat-row{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}.stat{background:var(--card);border:1px solid var(--line);border-radius:13px;padding:17px 10px;text-align:center}.stat b{display:block;font-family:Georgia,serif;font-size:29px;font-weight:400;color:var(--accent);line-height:1.2}.stat span{display:block;color:var(--muted);font-size:12px;margin-top:7px}.section-title{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:28px 0 18px}.section-title h2{font-size:24px;margin:0}.section-title a{font-size:12px}.chapter-preview{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.chapter-tile{display:block;background:var(--card);border:1px solid var(--line);border-radius:13px;padding:20px;color:var(--ink)}.chapter-tile:hover{border-color:var(--hover-line)}.chapter-tile .chapter-num{font-family:Georgia,serif;font-size:30px;color:var(--deco);margin-bottom:13px}.chapter-tile h3{font-size:16px;line-height:1.4;margin-bottom:13px;letter-spacing:-.02em}.chapter-tile small{color:var(--muted);font-size:12px}.daily-list{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.daily-card{display:flex;flex-direction:column;gap:13px}.daily-card h3{font-size:16px;line-height:1.45;margin:0;letter-spacing:-.02em}.daily-card .btn{margin-top:auto}.pill{display:inline-flex;gap:5px;align-items:center;border-radius:99px;padding:4px 9px;background:var(--light);color:var(--accent);font-size:12px;line-height:1.4;max-width:100%}.pill.gold{background:#f6ecd4;color:#84642a}.pill.gray{background:#eceff4;color:#4f5b6b}.pill.warn{background:#faeee3;color:#86570f}.pill.error{background:#fae9e7;color:var(--danger)}.tags{display:flex;flex-wrap:wrap;gap:7px}.callout{background:var(--soft);border:1px solid var(--soft-line);border-radius:12px;padding:16px 18px;font-size:13px;line-height:1.7}.callout p:last-child{margin-bottom:0}.callout.warn{background:#fbf4e5;border-color:#ebdebb;color:#765b28}.callout.error{background:#fff0ed;border-color:#edccc6;color:var(--danger)}.chapter-list{display:grid;gap:12px}.chapter-row{background:var(--card);border:1px solid var(--line);border-radius:13px;display:grid;grid-template-columns:54px 1fr auto;align-items:center;gap:15px;padding:20px;color:var(--ink)}.chapter-row:hover{border-color:var(--hover-line)}.chapter-row .num{font:29px Georgia,serif;color:var(--deco)}.chapter-row h3{font-size:17px;line-height:1.4;margin:0 0 8px;letter-spacing:-.02em}.chapter-row .meta{font-size:12px;color:var(--muted)}.chapter-row .chev{font-size:20px;color:var(--muted)}.chapter-row .progress-bar{width:100px;margin:8px 0 0;height:3px}.back-link{font-size:12px;min-height:40px;display:inline-flex;align-items:center;gap:8px;margin-bottom:17px}.reader-layout{display:grid;grid-template-columns:210px minmax(0,1fr);gap:24px;align-items:start}.reader-toc{position:sticky;top:20px;padding:15px}.reader-toc h3{font-size:12px;letter-spacing:0;margin:2px 8px 13px}.reader-toc a{display:block;color:var(--muted);font-size:12px;line-height:1.6;padding:10px 8px;border-radius:8px;min-height:42px}.reader-toc a.active{background:var(--light);color:var(--accent);font-weight:650}.reader-toc a .check{float:right;color:var(--accent);margin-left:5px}.reader-card{padding:30px;min-width:0}.reader-card h2{font-size:27px;line-height:1.3;margin-bottom:26px}.prose{font-family:Georgia,"Times New Roman",serif;font-size:var(--body-size);line-height:1.9;overflow-wrap:anywhere}.prose p{margin:0 0 1em}.prose h2,.prose h3,.prose h4{font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;line-height:1.5;letter-spacing:-.02em}.prose h3{font-size:20px;margin-top:28px}.prose h4{font-size:18px}.prose ul,.prose ol{padding-left:25px}.prose li{margin:8px 0}.prose table{border-collapse:collapse;font-size:15px;max-width:100%;display:block;overflow:auto}.prose td,.prose th{padding:8px 12px;border:1px solid var(--line)}.prose .box,.prose .studybox,.prose .warningbox,.prose .notebox,.prose .idea,.prose .theorem,.prose .definition{border-left:3px solid #6f9fd4;padding:13px 16px;background:var(--soft);margin:20px 0;border-radius:0 9px 9px 0}.prose .warningbox{background:#fbf3df;border-color:var(--gold)}.prose .math-display,.katex-display{overflow-x:auto;overflow-y:hidden;padding:6px 0}.katex{font-size:1.06em!important}.katex-error{white-space:normal!important;font-size:13px}.reader-actions{border-top:1px solid var(--line);margin-top:28px;padding-top:22px;display:flex;flex-wrap:wrap;justify-content:space-between;gap:12px}.section-select{display:none;width:100%;margin:0 0 16px;font-size:13px}.filters{display:grid;grid-template-columns:2fr 1.3fr 1fr 1fr;gap:10px;margin:22px 0 14px}.filters input,.filters select{min-width:0;width:100%;font-size:12px}.result-line{font-size:12px;color:var(--muted);margin:14px 0 17px;display:flex;justify-content:space-between;gap:10px}.problem-list{display:grid;gap:12px}.problem-row{display:grid;grid-template-columns:1fr auto;gap:12px;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:20px;color:var(--ink)}.problem-row:hover{border-color:var(--hover-line)}.problem-row h3{font-size:16px;line-height:1.5;letter-spacing:-.01em;margin:9px 0 5px}.problem-row .excerpt{font-size:12px;color:var(--muted);max-height:42px;overflow:hidden;margin-top:8px}.problem-row .arrow{align-self:center;color:var(--muted)}.pagination{display:flex;justify-content:center;align-items:center;gap:14px;margin-top:25px;font-size:12px}.problem-heading{display:flex;justify-content:space-between;align-items:start;gap:15px;margin-bottom:22px}.problem-heading h1{font-size:30px;line-height:1.3;margin:12px 0}.bookmark{border:1px solid var(--line);background:var(--card);min-width:46px;min-height:46px;font-size:23px;color:var(--muted);border-radius:50%}.bookmark.active{background:#fbefcf;color:#aa7926;border-color:#e8d19e}.problem-columns{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:22px;align-items:start}.problem-content{min-width:0;display:grid;gap:18px}.statement{padding:28px}.source-line{font-size:12px;color:var(--muted);border-top:1px solid var(--line);padding-top:16px;margin-top:24px;overflow-wrap:anywhere}.draft-card h2{font-size:21px}.autosave{font-size:12px;color:var(--muted);display:block;margin-top:9px}.check-panel{position:sticky;top:20px}.check-panel h3{font-size:16px}.check-item{display:flex;align-items:start;gap:10px;font-size:12px;margin:15px 0;line-height:1.6}.check-item input{margin:2px 0 0}.check-panel .btn{margin-top:15px}.check-panel .small{font-size:12px;margin-top:12px;line-height:1.7;color:var(--muted)}details{border:1px solid var(--line);border-radius:12px;background:var(--card);overflow:hidden}details summary{padding:18px 22px;cursor:pointer;font-weight:650;font-size:14px;min-height:55px}details>div{padding:0 22px 22px}.hint-block{border-left:2px solid var(--gold);padding:12px 15px;background:#faf6e9;margin:12px 0;font-size:15px}.photo-row{display:flex;align-items:center;flex-wrap:wrap;gap:12px;margin:17px 0}.photo-button{position:relative;overflow:hidden}.photo-button input{position:absolute;inset:0;opacity:0;width:100%;height:100%;cursor:pointer}.photo-preview{max-width:100%;max-height:240px;border:1px solid var(--line);border-radius:10px;display:block;margin-top:13px}.ai-result{margin-top:20px;border-top:1px solid var(--line);padding-top:20px}.ai-result blockquote{border-left:3px solid #9db7d6;padding:10px 14px;margin:12px 0;font-size:13px;color:var(--muted);background:#eef2f8;white-space:pre-wrap}.ai-result p{font-size:13px;white-space:pre-wrap;line-height:1.7}.ai-result h3{font-size:17px}.ai-result ol{padding-left:20px;font-size:13px}.loading-text{font-size:13px;color:var(--accent);margin-top:14px}.ai-panel h2{font-size:21px}.ai-panel .intro-copy{font-size:12px;color:var(--muted);line-height:1.8}.field{margin-bottom:20px}.field>span{display:block;font-size:12px;font-weight:650;margin-bottom:8px}.field small{display:block;color:var(--muted);font-size:12px;line-height:1.7;margin-top:7px}.field input,.field select{width:100%}.settings-grid{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(0,1fr);gap:24px;align-items:start}.settings-grid .card{min-width:0}.settings-grid h2{font-size:23px;margin-bottom:22px}.empty{padding:40px 24px;text-align:center;background:var(--card);border:1px dashed var(--line-strong);border-radius:14px}.empty .symbol{font:42px Georgia,serif;color:var(--deco);margin-bottom:15px}.empty h3{font-size:19px}.empty p{font-size:13px;color:var(--muted);max-width:430px;margin:0 auto 20px}.progress-overview{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-bottom:25px}.progress-chapter{display:grid;grid-template-columns:1fr auto;gap:15px;margin-bottom:15px}.progress-chapter h3{font-size:14px;line-height:1.5;margin-bottom:6px}.progress-chapter .small{font-size:12px}.progress-chapter .progress-bar{margin-top:10px}.progress-note{margin:20px 0}.saved-tabs{display:flex;gap:8px;flex-wrap:wrap;margin:22px 0}.saved-tabs button{min-height:42px;border:1px solid var(--line);padding:9px 14px;background:var(--card);color:var(--muted);font-size:12px}.saved-tabs button.active{background:var(--light);color:var(--accent);border-color:#9dbbe0}#toast{position:fixed;bottom:25px;left:calc(50% + 125px);transform:translateX(-50%);background:var(--navy);color:#fff;padding:12px 19px;border-radius:10px;z-index:80;font-size:12px;box-shadow:0 4px 15px #0002;max-width:85%;display:none}#toast.visible{display:block}.mono{font-family:ui-monospace,SFMono-Regular,monospace;font-size:12px}.section-toc-mobile{display:none}
:root[data-theme=dark]{--paper:#0f1722;--card:#172232;--ink:#e7ecf3;--muted:#a3b2c5;--line:#263549;--accent:#7db8f2;--accent-mid:#5aa2ea;--light:#1c2f47;--soft:#1d2f47;--soft-line:#33496a;--hover-line:#4a6a93;--gold:#f0b23a;--navy:#0a111b;--book:#152b45;--danger:#f2a091;--nav-ink:#c0cddd;--deco:#6f87a3;--control-line:#6a809b;--track:#2a3b52;--shelf:#22314a;--line-strong:#3a4e68;--focus:#f0b23a;color-scheme:dark}:root[data-theme=dark] .btn{background:#1d6fc4;color:white;border-color:#3b86d6}:root[data-theme=dark] .btn.secondary{background:var(--card);color:var(--ink);border-color:var(--control-line)}:root[data-theme=dark] .callout,:root[data-theme=dark] .prose .box,:root[data-theme=dark] .prose .studybox,:root[data-theme=dark] .prose .idea{background:#1d2f47;border-color:#35506f}:root[data-theme=dark] .callout.warn,:root[data-theme=dark] .hint-block,:root[data-theme=dark] .prose .warningbox{background:#3a301a;color:#eadcb6;border-color:#716039}:root[data-theme=dark] .pill{background:#1f3a58;color:#b5d6f7}:root[data-theme=dark] .pill.gray{background:#2a394d;color:#c4d0df}:root[data-theme=dark] .pill.gold{background:#514632;color:#e8c680}:root[data-theme=dark] .ai-result blockquote{background:#1a2a3e}:root[data-theme=dark] .pill.error,:root[data-theme=dark] .callout.error{background:#54372f;color:#f6b1a2;border-color:#754e43}
@media(min-width:1450px){main{padding-top:48px}.hero-grid{gap:30px}.book-card{min-height:420px}.chapter-preview,.daily-list{gap:20px}}
@media(max-width:1120px){.sidebar{width:213px;padding:27px 16px}.brand{font-size:21px}.brand small{font-size:12px}.brand-mark{width:35px}.workspace{margin-left:213px}.topbar{padding:0 27px}main{padding:32px 27px}.hero-grid{gap:17px}.book-card{padding:28px 25px}.book-card h2{font-size:35px}.reading-card{padding:21px}.stat{padding:15px 6px}.stat span{font-size:12px}.chapter-preview,.daily-list{gap:11px}.chapter-tile,.daily-card{padding:18px}.problem-columns{grid-template-columns:minmax(0,1fr) 230px;gap:17px}.check-panel{padding:20px}.reader-layout{grid-template-columns:170px minmax(0,1fr);gap:17px}.reader-card{padding:25px}.filters{grid-template-columns:1.5fr 1.2fr 1fr}.filters select:last-child{grid-column:3}.filters input{grid-column:1 / 3}.filters select:nth-child(2){grid-column:1}.page-footer{padding-left:27px;padding-right:27px}#toast{left:calc(50% + 106px)}}
@media(max-width:850px){.sidebar{display:none}.workspace{margin-left:0}.topbar{height:68px;padding:0 23px}.breadcrumb{display:none}.mobile-brand{display:flex;align-items:center;gap:8px;color:var(--ink);font:27px Georgia,serif}.mobile-brand b{font:750 20px -apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;letter-spacing:-.05em}.bottom-nav{position:fixed;bottom:0;left:0;right:0;background:var(--card);border-top:1px solid var(--line);display:grid;grid-template-columns:repeat(5,1fr);z-index:30;padding-bottom:env(safe-area-inset-bottom)}.bottom-nav a{color:var(--muted);min-height:65px;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:2px}.bottom-nav a span{font-size:24px;line-height:1.2}.bottom-nav a small{font-size:12px}.bottom-nav a.active{color:var(--accent);background:var(--light)}main{padding:30px 23px 35px;min-height:calc(100vh - 140px)}.page-footer{padding:20px 23px 95px}#toast{left:50%;bottom:85px}.hero-grid{grid-template-columns:1fr 1fr}.book-card{min-height:366px}.book-card h2{font-size:35px}.reader-layout{grid-template-columns:1fr}.reader-toc{display:none}.section-select{display:block}.problem-columns{grid-template-columns:minmax(0,1fr) 230px}.reader-card{padding:28px}.settings-grid{gap:17px}}
@media(max-width:620px){.topbar{height:63px;padding:0 19px}.offline-badge{font-size:12px;padding:6px 9px}.mobile-brand b{font-size:19px}main{padding:27px 18px 32px}h1{font-size:31px;line-height:1.17}.intro{margin-bottom:24px}.intro p{font-size:13px;line-height:1.7}.eyebrow{font-size:12px}.hero-grid{grid-template-columns:1fr;gap:20px;margin-bottom:30px}.book-card{min-height:350px;padding:28px 30px;box-shadow:0 7px 0 -3px var(--shelf),0 10px 25px -15px #1f355044}.book-card .eyebrow{margin-bottom:22px}.book-card h2{font-size:41px;max-width:260px}.book-card .book-bottom{padding-top:22px}.book-number{bottom:37px;font-size:180px}.book-lines{top:21px;right:-103px}.reading-card{padding:22px}.reading-card h3{font-size:24px;max-width:none}.learning-panel{gap:12px}.stat-row{gap:10px}.stat{padding:15px 8px}.stat b{font-size:29px}.stat span{font-size:12px}.chapter-preview,.daily-list{grid-template-columns:1fr}.chapter-tile{display:grid;grid-template-columns:42px 1fr;column-gap:15px;align-items:start;padding:20px}.chapter-tile .chapter-num{grid-row:1/3;margin:0;font-size:31px}.chapter-tile h3{font-size:16px;margin:0 0 9px}.chapter-tile small{grid-column:2}.daily-card{padding:21px;display:grid;grid-template-columns:1fr auto;align-items:center;gap:9px 15px}.daily-card .tags{grid-column:1/3}.daily-card h3{font-size:16px}.daily-card .btn{align-self:center}.section-title{margin-top:26px}.section-title h2{font-size:23px}.section-title a{font-size:12px}.page-heading{align-items:start}.page-heading h2{font-size:24px}.page-heading .btn{padding:9px 12px;font-size:12px}.card{padding:22px}.chapter-row{grid-template-columns:35px 1fr 12px;gap:12px;padding:18px 16px}.chapter-row h3{font-size:15px;line-height:1.45}.chapter-row .num{font-size:27px}.chapter-row .meta{font-size:12px}.reader-card{padding:22px 19px}.reader-card h2{font-size:24px}.prose{font-size:var(--body-size);line-height:1.85}.prose h3{font-size:19px}.prose .box,.prose .studybox,.prose .warningbox,.prose .notebox,.prose .idea{padding:12px;font-size:16px}.reader-actions{gap:10px}.reader-actions .btn{flex:1;font-size:12px;padding:11px}.filters{grid-template-columns:1fr 1fr;gap:9px}.filters input{grid-column:1/3}.filters select:nth-child(2){grid-column:1/3}.filters select:last-child{grid-column:auto}.filters select{font-size:12px}.problem-row{padding:17px}.problem-row h3{font-size:15px}.problem-row .excerpt{font-size:12px}.problem-heading h1{font-size:26px;line-height:1.3}.problem-columns{grid-template-columns:1fr;gap:18px}.check-panel{position:static;grid-row:2}.check-panel h3{font-size:18px}.check-item{font-size:13px}.problem-content{gap:15px}.statement{padding:23px 20px}.problem-heading{gap:12px}.bookmark{min-width:43px;min-height:43px}.draft-card,.ai-panel{padding:22px 20px}details summary{padding:17px 20px}details>div{padding:0 20px 20px}.settings-grid{grid-template-columns:1fr;gap:18px}.settings-grid h2{font-size:23px}.progress-overview{grid-template-columns:repeat(2,1fr);gap:11px}.progress-overview .stat{padding:21px 8px}.progress-chapter{grid-template-columns:1fr auto;gap:12px;margin-bottom:23px}.progress-chapter h3{font-size:13px;line-height:1.5}.progress-chapter .btn{font-size:12px;padding:8px 10px}.progress-chapter .small{font-size:12px}.progress-note{font-size:12px}.page-footer{padding:18px 19px 96px;font-size:12px}.page-footer span{display:none}.callout{font-size:12px;padding:15px}.button-row .btn{font-size:12px}.pagination{gap:10px}.pagination .btn{font-size:12px}.section-select{font-size:12px}.photo-row{gap:9px}.photo-row .small{font-size:12px}.source-line{font-size:12px}.intro .button-row{margin-top:18px}.saved-tabs button{padding:9px 11px;font-size:12px}.result-line{font-size:12px}.reader-card .prose{overflow-x:auto}.check-panel .small{font-size:12px}}
@media(prefers-reduced-motion:no-preference){.chapter-tile,.chapter-row,.problem-row,.btn{transition:border-color .15s,background .15s,filter .15s}}

/* Isbot: book library and official institute credit. */
.book-library{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:24px;margin-bottom:32px}.book-library .book-card{min-height:390px}.book-library .book-card h2{max-width:330px;font-size:38px}.book-library .book-card.selected{outline:2px solid #6f9fd4;outline-offset:5px}.book-card.number-theory{background:#5a393b}.book-card.number-theory .eyebrow,.book-card.number-theory .book-subtitle,.book-card.number-theory .book-author small{color:#dbc9b9}.book-card.number-theory .book-number{color:#e7be8d16}.book-card.combinatorics{background:#244d40}.book-card.combinatorics .eyebrow,.book-card.combinatorics .book-subtitle,.book-card.combinatorics .book-author small{color:#c2d5bb}.book-card.combinatorics .book-number{color:#c6d9a619}.book-card.combinatorics .book-lines,.book-card.combinatorics .book-lines:before,.book-card.combinatorics .book-lines:after{border-color:#d4cd7829}.book-card.geometry{background:#343e6b}.book-card.geometry .eyebrow,.book-card.geometry .book-subtitle,.book-card.geometry .book-author small{color:#c9d1ec}.book-card.geometry .book-number{color:#a9bee820}.book-card.geometry .book-lines,.book-card.geometry .book-lines:before,.book-card.geometry .book-lines:after{border-color:#b9c7ed2e}.book-card.general{background:#3d435d}.book-card .book-meta{font-size:12px;color:#c3d1e4;position:relative;z-index:1}.current-book{position:absolute;right:20px;top:18px;font-size:12px;color:#e6d5a6;background:#ffffff10;padding:5px 9px;border-radius:20px}.book-library .book-card .eyebrow{padding-top:12px}.home-learning{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(200px,1fr);gap:23px;margin:0 0 34px}.home-learning .stat-row{grid-template-columns:1fr}.home-learning .stat{display:flex;align-items:center;gap:15px;text-align:left;padding:13px 20px}.home-learning .stat b{min-width:65px}.home-learning .stat span{margin:0;font-size:12px}.home-learning .reading-card h3{max-width:none}.book-switch{display:flex;gap:13px;align-items:center;flex-wrap:wrap;margin:0 0 25px;padding:15px 18px;background:var(--light);border-radius:12px}.book-switch label{font-size:12px;color:var(--accent);font-weight:650}.book-switch select{flex:1;min-width:190px;font-size:12px;background:var(--card)}.book-switch a{font-size:12px;white-space:nowrap}.multi-filters{grid-template-columns:2fr 1.4fr 1fr 1fr}.multi-filters input{grid-column:1/3}.multi-filters #bookFilter{grid-column:3/5}.multi-filters #chapterFilter{grid-column:1/3}.header-institute{display:flex;align-items:center;gap:11px;max-width:370px;min-width:0}.header-institute img{height:54px;width:54px;object-fit:contain;flex-shrink:0}.header-institute span{font-size:12px;line-height:1.6;color:var(--muted);max-width:270px}.header-institute b{font-size:15px;color:var(--ink);font-weight:650}.institute-credit{display:flex;align-items:center;gap:27px;padding:29px;margin-top:34px;border:1px solid var(--line);background:var(--card);border-radius:17px}.institute-credit img{width:103px;height:103px;object-fit:contain;flex-shrink:0}.institute-credit .eyebrow{font-size:12px;margin-bottom:10px}.institute-credit h2{font-size:19px;line-height:1.5;letter-spacing:-.02em;margin-bottom:10px}.institute-credit p{font-size:12px;color:var(--muted);margin-bottom:10px}.institute-credit a{font-size:12px}.page-footer{line-height:1.8}.footer-english{text-align:right}.brand-mark{font-size:37px}.brand{font-size:28px}.brand small{font-size:12px;letter-spacing:0}.brand-mark{font-family:Georgia,serif}
@media(max-width:1120px){.book-library{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.book-library .book-card h2{font-size:36px}.book-library .book-card{padding:28px 26px;min-height:365px}.home-learning{grid-template-columns:minmax(0,1.5fr) minmax(180px,1fr)}}
@media(max-width:850px){.topbar{gap:18px}.header-institute img{width:48px;height:48px}.header-institute span{font-size:12px}.header-institute b{font-size:12.5px}.mobile-brand b{font-size:24px}.book-library{gap:17px}.book-library .book-card{padding:29px 24px}.book-library .book-card h2{font-size:34px}.book-library .book-card .book-bottom{align-items:start;flex-direction:column;gap:18px}.home-learning{grid-template-columns:minmax(0,1.4fr) minmax(180px,1fr)}.footer-english{display:none}}
@media(max-width:620px){.book-library{grid-template-columns:1fr;gap:25px;margin-bottom:31px}.book-library .book-card{min-height:340px;padding:29px 28px}.book-library .book-card h2{font-size:41px;max-width:280px}.book-library .book-card .book-bottom{flex-direction:row;align-items:end;gap:12px}.book-library .book-card .book-number{font-size:155px;bottom:54px}.current-book{font-size:12px;right:15px;top:14px}.home-learning{display:flex;flex-direction:column;gap:13px}.home-learning .stat-row{grid-template-columns:repeat(3,minmax(0,1fr));gap:8px}.home-learning .stat{display:block;text-align:center;padding:14px 7px}.home-learning .stat b{min-width:0;font-size:27px}.home-learning .stat span{font-size:12px;margin-top:7px}.header-institute{max-width:230px;gap:8px}.header-institute img{width:44px;height:44px}.header-institute span{font-size:12px;line-height:1.5}.header-institute b{font-size:12px}.topbar{padding:0 17px}.mobile-brand{font-size:30px;gap:8px}.mobile-brand b{font-size:24px}.book-switch{padding:14px;gap:10px}.book-switch select{width:100%;min-width:0;flex-basis:100%;font-size:12px}.book-switch a{font-size:12px}.multi-filters{grid-template-columns:1fr 1fr}.multi-filters input,.multi-filters #bookFilter,.multi-filters #chapterFilter{grid-column:1/3}.multi-filters #kindFilter,.multi-filters #statusFilter{grid-column:auto}.institute-credit{padding:21px 18px;gap:16px;align-items:start;margin-top:27px}.institute-credit img{width:63px;height:63px}.institute-credit h2{font-size:13px;line-height:1.65;margin-bottom:8px}.institute-credit .eyebrow{font-size:12px;letter-spacing:.06em}.institute-credit p{font-size:12px;line-height:1.7}.institute-credit a{font-size:12px}.page-footer{font-size:12px}.brand small{font-size:12px}}

/* Preserve source geometry while making small diagram labels readable. */
.prose img.geometry-diagram{min-width:min(260px,100%);max-width:100%;height:auto}
.prose figure img.geometry-diagram{min-width:260px;max-width:none;height:auto}
.problem-content>*{min-width:0}

/* Six volumes form two balanced shelf rows on a wide screen. */
.book-card.advanced-algebra{background:#70442f}.book-card.advanced-algebra .eyebrow,.book-card.advanced-algebra .book-subtitle,.book-card.advanced-algebra .book-author small{color:#ead0bc}.book-card.advanced-algebra .book-number{color:#f3c99e1c}.book-card.advanced-algebra .book-lines,.book-card.advanced-algebra .book-lines:before,.book-card.advanced-algebra .book-lines:after{border-color:#f0c99b30}.book-library .book-card.advanced-algebra h2{max-width:440px}
.book-card.advanced-methods{background:#51435f}.book-card.advanced-methods .eyebrow,.book-card.advanced-methods .book-subtitle,.book-card.advanced-methods .book-author small{color:#ddd0e5}.book-card.advanced-methods .book-number{color:#dec4f01c}.book-card.advanced-methods .book-lines,.book-card.advanced-methods .book-lines:before,.book-card.advanced-methods .book-lines:after{border-color:#d4bbea30}
@media(min-width:1280px){.book-library{grid-template-columns:repeat(3,minmax(0,1fr))}.book-library>.book-card{padding:30px 27px}.book-library>.book-card h2{font-size:36px}.book-library>.book-card .book-bottom{align-items:start;flex-direction:column;gap:18px}}
@media(max-width:620px){.book-library .book-card.advanced-algebra h2{font-size:37px;max-width:100%}}

/* Book-based multiple-choice practice. */
.quiz-home-card{display:flex;align-items:center;justify-content:space-between;gap:24px;border:1px solid var(--soft-line);background:var(--light);border-radius:17px;padding:25px 28px;margin-bottom:31px}.quiz-home-card h2{font-size:25px;margin-bottom:8px}.quiz-home-card p{font-size:13px;color:var(--muted);max-width:620px;margin:0}.quiz-home-card .eyebrow{margin-bottom:8px}.quiz-home-card>.btn{flex-shrink:0}.quiz-hero{display:grid;grid-template-columns:minmax(0,1fr) 200px;gap:35px;align-items:center}.quiz-hero h2{font-family:Georgia,serif;font-size:35px;font-weight:400;margin:18px 0 16px}.quiz-hero p{font-size:14px;color:var(--muted);max-width:600px;line-height:1.8}.quiz-stat{border-left:1px solid var(--line);text-align:center;padding:12px 0 12px 25px;display:grid;gap:8px}.quiz-stat b{font-family:Georgia,serif;font-size:33px;font-weight:400;color:var(--accent)}.quiz-stat span,.quiz-stat small{font-size:12px;color:var(--muted)}.quiz-local-note{margin:17px 0 28px;line-height:1.8}.quiz-history{display:grid;gap:10px}.quiz-history-row{width:100%;display:flex;align-items:center;justify-content:space-between;gap:15px;text-align:left;padding:19px 22px;background:var(--card);border:1px solid var(--line);color:var(--ink);border-radius:12px}.quiz-history-row:hover{border-color:var(--accent)}.quiz-history-row strong{font-size:14px;display:block}.quiz-history-row small{display:block;color:var(--muted);font-size:12px;margin-top:7px}.quiz-history-row>b{font-size:20px;white-space:nowrap;color:var(--accent)}.quiz-history-row>b span{font-size:16px;margin-left:13px}.quiz-topline,.quiz-status{display:flex;justify-content:space-between;align-items:center;gap:14px;margin-bottom:20px}.quiz-status{font-size:13px;margin-bottom:12px}.quiz-progress{height:5px;background:var(--line);border-radius:5px;margin-bottom:25px;overflow:hidden}.quiz-progress i{display:block;height:100%;background:var(--accent);transition:width .2s}.quiz-layout{display:grid;grid-template-columns:minmax(0,1fr) 240px;gap:22px;align-items:start}.quiz-layout>*{min-width:0}.quiz-question fieldset{border:0;padding:0;margin:25px 0 0;min-width:0}.quiz-question legend{display:block;width:100%;padding:0;margin-bottom:22px;line-height:1.8}.quiz-question legend .prose{font-size:20px;display:block}.quiz-question legend p:last-child{margin-bottom:0}.quiz-options{display:grid;gap:12px}.quiz-option{display:flex;align-items:center;gap:12px;padding:16px;border:1px solid var(--line);background:var(--card);border-radius:12px;cursor:pointer;min-height:65px}.quiz-option:hover{border-color:var(--hover-line)}.quiz-option.selected{background:var(--light);border-color:var(--accent);box-shadow:0 0 0 1px var(--accent)}.quiz-option input{accent-color:var(--accent);width:20px;height:20px;min-height:20px;margin:0;flex-shrink:0}.quiz-option .prose{min-width:0;line-height:1.6;font-size:18px}.quiz-option .prose p:last-child{margin-bottom:0}.quiz-letter{flex-shrink:0;font-size:12px;font-weight:700;color:var(--muted)}.quiz-question-actions{display:flex;justify-content:space-between;align-items:center;gap:15px;flex-wrap:wrap;margin:13px 0 23px}.quiz-question-actions span{font-size:12px}.quiz-prevnext{display:flex;justify-content:space-between;gap:15px;padding-top:22px;border-top:1px solid var(--line)}.quiz-map h2{font-size:20px;margin-bottom:12px}.quiz-map>p{line-height:1.7}.quiz-grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:7px;margin:20px 0}.quiz-number{height:36px;padding:0;background:var(--card);border:1px solid var(--line);color:var(--muted);border-radius:8px;font-size:12px}.quiz-number.answered{background:var(--light);color:var(--accent);border-color:#9dbbe0}.quiz-number.current{outline:2px solid var(--accent);outline-offset:1px;color:var(--ink);font-weight:800}.quiz-map-key{display:flex;align-items:center;gap:8px;font-size:12px}.quiz-map-key span{display:block;width:11px;height:11px;border-radius:3px;background:var(--light);border:1px solid #9dbbe0}.quiz-map>.btn{font-size:12px}.quiz-confirm{margin-top:22px}.quiz-confirm h2{font-size:21px}.quiz-result{display:flex;align-items:center;justify-content:space-between;gap:24px;flex-wrap:wrap}.quiz-score strong{font-family:Georgia,serif;font-size:55px;font-weight:400;line-height:1.2;display:block;color:var(--accent)}.quiz-score strong small{font-family:Inter,-apple-system,sans-serif;font-size:17px;color:var(--muted)}.quiz-score>span{display:block;font-size:12px;color:var(--muted);margin-top:7px}.quiz-result-counts{display:flex;gap:23px}.quiz-result-counts span{display:grid;gap:7px;text-align:center;color:var(--muted);font-size:12px}.quiz-result-counts b{font-size:25px;color:var(--ink)}.quiz-review-list{display:grid;gap:12px}.quiz-review{border:1px solid var(--line);background:var(--card);border-radius:13px;overflow:hidden}.quiz-review>summary{display:flex;align-items:center;gap:13px;cursor:pointer;list-style:none;padding:17px 20px;font-size:13px;background:transparent;line-height:1.6}.quiz-review>summary::-webkit-details-marker{display:none}.quiz-review>summary:after{content:'+';font-size:21px;font-weight:400;color:var(--muted);margin-left:7px}.quiz-review[open]>summary:after{content:'−'}.quiz-review-number{font-family:Georgia,serif;font-size:23px;color:var(--muted);min-width:25px}.quiz-verdict{margin-left:auto;font-size:12px;white-space:nowrap}.quiz-verdict.correct{color:var(--accent)}.quiz-verdict.wrong{color:var(--danger)}.quiz-review-body{padding:8px 24px 24px;border-top:1px solid var(--line)}.quiz-review-body>.prose{margin:15px 0 20px}.quiz-review-options{list-style:none;padding:0;margin:0 0 23px;display:grid;gap:9px}.quiz-review-options li{border:1px solid var(--line);padding:13px;border-radius:9px;font-family:Georgia,serif;font-size:17px;line-height:1.7;overflow-wrap:anywhere}.quiz-review-options li>span{display:block}.quiz-review-options li small{font:12px/1.6 Inter,-apple-system,sans-serif;color:var(--muted);display:block;margin-top:4px}.quiz-review-options li.is-selected{border-left:4px solid var(--danger)}.quiz-review-options li.is-correct{border-color:var(--accent);background:var(--light)}.quiz-review-options li.is-correct small{color:var(--accent)}.quiz-explanation{border-left:3px solid var(--accent);padding:12px 16px;margin:20px 0;background:var(--light);border-radius:0 9px 9px 0}.quiz-explanation>strong{display:block;font-size:12px;color:var(--accent);margin-bottom:10px}.quiz-explanation p:last-child{margin-bottom:0}.quiz-question .katex-display,.quiz-review .katex-display{max-width:100%}.quiz-topline .btn{flex-shrink:0}:root[data-theme=dark] .quiz-home-card{border-color:var(--line)}:root[data-theme=dark] .quiz-verdict.wrong{color:#f6b1a2}:root[data-theme=dark] .quiz-review-options li.is-selected{border-left-color:#e7a08d}.quiz-layout button:disabled{cursor:default}
@media(max-width:1100px){.quiz-layout{grid-template-columns:minmax(0,1fr) 205px}.quiz-map{padding:20px 16px}}
@media(max-width:850px){.bottom-nav{grid-template-columns:repeat(6,minmax(0,1fr))}.bottom-nav a small{font-size:12px}.quiz-layout{grid-template-columns:minmax(0,1fr)}.quiz-map{padding:23px}.quiz-grid{grid-template-columns:repeat(10,minmax(0,1fr))}.quiz-map>.btn{width:auto}.quiz-home-card{padding:23px}.quiz-home-card h2{font-size:23px}}
@media(max-width:620px){.quiz-home-card{align-items:start;flex-direction:column;gap:20px}.quiz-home-card .btn{width:100%}.quiz-hero{grid-template-columns:minmax(0,1fr);gap:25px;padding:23px}.quiz-hero h2{font-size:30px}.quiz-hero .button-row .btn{width:100%}.quiz-stat{border-left:0;border-top:1px solid var(--line);padding:22px 0 0;grid-template-columns:1fr 1fr;text-align:left;align-items:center}.quiz-stat b{grid-row:1/3;font-size:31px}.quiz-stat span,.quiz-stat small{text-align:right}.quiz-question{padding:22px 18px}.quiz-question legend .prose{font-size:19px}.quiz-option{padding:14px 11px;gap:9px}.quiz-option .prose{font-size:17px}.quiz-status{align-items:start;flex-direction:column;gap:5px}.quiz-topline{gap:8px;align-items:start}.quiz-topline>span{font-size:12px;text-align:right;margin-top:10px}.quiz-grid{grid-template-columns:repeat(5,minmax(0,1fr));gap:9px}.quiz-number{height:40px;font-size:13px}.quiz-result{padding:24px;gap:25px}.quiz-result>.btn{width:100%}.quiz-result-counts{gap:17px}.quiz-score strong{font-size:49px}.quiz-score strong small{font-size:14px}.quiz-review>summary{padding:15px 13px;gap:9px}.quiz-review>summary>span:nth-child(2){font-size:12px}.quiz-review-body{padding:7px 17px 23px}.quiz-history-row{padding:17px 15px}.quiz-history-row>b{font-size:17px}.quiz-history-row strong{font-size:12px}.quiz-history-row small{font-size:12px}.quiz-history-row>b span{margin-left:4px}.quiz-question-actions{gap:3px}.quiz-confirm .button-row>.btn{width:100%}}

/* Selected official Isbot app mark. */
.brand .brand-logo{width:48px;height:48px;object-fit:contain;border-radius:12px;flex-shrink:0;background:#131210}
.mobile-logo{width:38px;height:38px;object-fit:contain;border-radius:10px;flex-shrink:0}
@media(max-width:360px){.mobile-brand b{font-size:21px}.mobile-logo{width:32px;height:32px}.header-institute{gap:7px;max-width:190px}.header-institute img{width:36px;height:36px}.header-institute b{font-size:12px}}

/* Long inline formulas stay within a narrow test card. */
.quiz-question .prose,.quiz-review .prose,.quiz-review-options li>span{max-width:100%;overflow-x:auto;overflow-y:hidden}
.quiz-review>summary>span:nth-child(2){min-width:0;overflow-wrap:anywhere}

/* Saved configuration applies only to the next attempt. */
.quiz-config{display:grid;grid-template-columns:minmax(0,1fr) 150px;gap:20px;align-items:start;margin:22px 0}.quiz-book-choices{min-width:0;border:0;padding:0;margin:0}.quiz-book-choices legend,.quiz-count-choice>span{display:block;font-size:12px;font-weight:700;color:var(--ink);margin:0 0 10px}.quiz-book-choice{display:flex;align-items:center;gap:12px;padding:12px;border:1px solid var(--line);border-radius:10px;margin-bottom:9px;background:var(--card);cursor:pointer}.quiz-book-choice input{margin:0}.quiz-book-choice strong{display:block;font-size:12px;line-height:1.6;font-weight:600}.quiz-book-choice small{display:block;color:var(--muted);font-size:12px;margin-top:3px}.quiz-count-choice select{width:100%;font-size:13px}.quiz-hero p.quiz-selection-summary{font-size:12px;color:var(--accent);line-height:1.8;margin-bottom:15px}.quiz-active-note{margin:0 0 18px;font-size:12px}.quiz-history-row>b small{font-size:12px;text-align:right;color:var(--muted);margin-top:4px;font-weight:500}.quiz-stat small{line-height:1.7}
@media(max-width:1120px){.quiz-hero{grid-template-columns:minmax(0,1fr)}.quiz-stat{border-left:0;border-top:1px solid var(--line);padding:18px 0 0;text-align:left;grid-template-columns:auto minmax(0,1fr);align-items:center;column-gap:20px}.quiz-stat b{grid-row:1/3}.quiz-stat small{grid-column:2}.quiz-stat span{align-self:end}.quiz-stat small{align-self:start}}
@media(max-width:620px){.quiz-config{grid-template-columns:minmax(0,1fr);gap:14px}.quiz-book-choice strong{font-size:12px}.quiz-count-choice{max-width:none}.quiz-history-row{align-items:start}.quiz-history-row>span{min-width:0}.quiz-history-row small{line-height:1.7}.quiz-history-row>b{padding-top:1px}.quiz-stat span,.quiz-stat small{text-align:right}.quiz-result .button-row{width:100%}.quiz-result .button-row>.btn{width:100%}}

/* Keep saved results readable while giving deletion a separate touch target. */
.quiz-history-heading{flex-wrap:wrap}
.quiz-history-tools{display:flex;align-items:center;flex-wrap:wrap;gap:12px}
.quiz-history-item{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:10px}
.quiz-history-row{min-width:0}
.quiz-history-row>span{min-width:0;overflow-wrap:anywhere}
.quiz-history-row>b{flex-shrink:0}
.quiz-history-delete.btn,.quiz-history-clear.btn{min-height:44px}
.quiz-history-delete{white-space:nowrap}
.quiz-delete-confirm{margin-top:22px}
.quiz-delete-confirm h2{font-size:23px;line-height:1.35}
@media(max-width:620px){.quiz-history-tools{width:100%;justify-content:space-between}.quiz-history-item{gap:8px}.quiz-history-delete.btn{padding:10px 11px;font-size:12px}.quiz-delete-confirm .button-row>.btn{width:100%}}

:root[data-theme=dark] .quiz-history-delete.btn,:root[data-theme=dark] .quiz-history-clear.btn,:root[data-theme=dark] .quiz-delete-confirm-button.btn{background:var(--card);border-color:#b67b70;color:#f6b1a2}
:root[data-theme=dark] .header-institute img{background:#fffefa;border-radius:50%;padding:2px}
 .quiz-delete-confirm-button.btn{background:var(--danger);border-color:var(--danger);color:#fff}
:root[data-theme=dark] .quiz-delete-confirm-button.btn{background:var(--card);border-color:#b67b70;color:#f6b1a2}
@media(max-width:360px){.quiz-history-item{grid-template-columns:minmax(0,1fr);gap:6px}.quiz-history-delete{justify-self:end;margin-bottom:4px}}

/* Theme polish: kunduzgi/tungi rejim, brauzer elementlari va qolgan qattiq ranglar. */
:root{accent-color:var(--accent)}
::selection{background:#bcd6f3;color:#0f2644}
:root[data-theme=dark] ::selection{background:#2e5688;color:#f4f8f2}
input,textarea{caret-color:var(--accent)}
::placeholder{color:var(--muted);opacity:1}
html{scrollbar-color:var(--deco) transparent}
:root[data-theme=dark] .callout,:root[data-theme=dark] .prose .box,:root[data-theme=dark] .prose .studybox,:root[data-theme=dark] .prose .idea,:root[data-theme=dark] .prose .notebox,:root[data-theme=dark] .prose .theorem,:root[data-theme=dark] .prose .definition{background:#1d2f47;border-color:#35506f}
:root[data-theme=dark] .pill.warn{background:#4a3d22;color:#f0d9a0}
:root[data-theme=dark] .bookmark.active{background:#4a3d22;color:#f0d9a0;border-color:#716039}
:root[data-theme=dark] .btn.danger{border-color:#b67b70;color:var(--danger)}
:root[data-theme=dark] .offline-badge{border-color:var(--line)}
:root[data-theme=dark] .quiz-number.answered,:root[data-theme=dark] .quiz-map-key span{border-color:#35506f}
:root[data-theme=dark] .progress-bar i{background:#5aa2ea}
:root[data-theme=dark] #toast{border:1px solid var(--line)}
:root[data-theme=dark] .prose img.geometry-diagram,:root[data-theme=dark] .prose figure img{filter:invert(.9) hue-rotate(180deg)}
:root[data-theme=dark] .photo-preview{filter:brightness(.92)}
.bottom-nav a{text-align:center;line-height:1.2}
.bottom-nav a small{overflow-wrap:anywhere}
.katex-error{color:var(--danger)}
:root[data-theme=dark] .book-card{outline:1px solid #ffffff1a;outline-offset:-1px}

/* Yuklanish ekrani: ilova tayyor bo'lguncha bo'sh sahifa ko'rinmaydi. */
.boot{display:grid;justify-items:center;align-content:center;gap:16px;min-height:55vh;text-align:center;color:var(--muted)}
.boot-logo{width:72px;height:72px;border-radius:18px;background:#131210;object-fit:contain}
.boot p{margin:0;font-size:15px}
.boot-bar{width:160px;height:4px;border-radius:4px;background:var(--track);overflow:hidden}
.boot-bar i{display:block;width:40%;height:100%;border-radius:4px;background:var(--accent-mid)}
@media(prefers-reduced-motion:no-preference){.boot-bar i{animation:boot-slide 1.1s ease-in-out infinite}}
@keyframes boot-slide{0%{transform:translateX(-100%)}100%{transform:translateX(350%)}}