:root{color-scheme:light;--ink:#252b34;--muted:#756e66;--gold:#ab8550;--gold-dark:#795d37;--line:#e9e2d7;--paper:#fffefa;--canvas:#f6f3ec;--navy:#293646;--shadow:0 18px 48px rgba(40,42,41,.07)}
*{box-sizing:border-box}body{margin:0;background:var(--canvas);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;-webkit-font-smoothing:antialiased}button{font:inherit;cursor:pointer}a{color:inherit;text-decoration:none}:focus-visible{outline:3px solid #bb8e4a;outline-offset:3px}[hidden]{display:none!important}.study-shell{max-width:1320px;margin:auto;padding:0 clamp(16px,3vw,42px)}
.site-header{height:88px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:12px}.brand-mark{width:42px;height:42px;border-radius:13px;display:grid;place-items:center;color:#fff7e7;background:linear-gradient(145deg,#3b4a5d,#1f2836);font-size:20px;font-weight:700;box-shadow:inset 0 0 0 1px rgba(225,195,138,.3)}.brand-name{display:flex;flex-direction:column;gap:1px;letter-spacing:.02em}.brand-name strong{font-size:17px}.brand-name small{font-size:11px;color:var(--muted);letter-spacing:.1em}.back-link{padding:9px 14px;border:1px solid #d6c7ad;border-radius:999px;color:var(--gold-dark);background:#fffcf6;font-size:12px;font-weight:700}.back-link:hover{border-color:#bda77f;background:#f8f0e2}
.intro{margin:28px 0 18px;padding:37px 42px;border-radius:25px;background:radial-gradient(circle at 78% 35%,rgba(219,182,111,.2),transparent 32%),linear-gradient(110deg,#182431,#303d4b 66%,#415063);color:#fff9ee}.eyebrow{margin:0 0 11px;color:#d4b781;font-size:11px;font-weight:700;letter-spacing:.24em}.intro h1{margin:0;font-size:clamp(29px,3vw,43px);line-height:1.35}.intro p:last-child{margin:12px 0 0;color:#d8dbe0;font-size:15px}.notice{display:flex;align-items:flex-start;gap:12px;padding:14px 17px;border:1px solid #e9ddc9;background:#fcf9f2;border-radius:14px}.notice-mark{flex:none;width:20px;height:20px;border:1px solid #ad8955;border-radius:50%;display:grid;place-items:center;color:#8b6837;font:700 13px Georgia,serif}.notice p{margin:0;color:#695f53;font-size:13px;line-height:1.7}.notice-emphasis{font-weight:800;color:#8b6837}
.catalog-section{margin:31px 0 24px}.section-heading,.panel-heading{display:flex;align-items:center;gap:11px}.section-heading{margin-bottom:14px}.section-heading>span,.panel-heading>span{font:700 12px Georgia,serif;color:var(--gold)}.section-heading h2,.panel-heading h2{margin:0;font-size:17px}.exam-tabs{display:flex;flex-wrap:wrap;gap:10px}.exam-tab{min-width:118px;border:1px solid var(--line);border-radius:13px;padding:12px 19px;background:var(--paper);color:#4e514f;font-size:14px;font-weight:750;transition:.2s}.exam-tab:hover{border-color:#b7a281;transform:translateY(-1px)}.exam-tab[aria-pressed="true"]{border-color:var(--navy);background:var(--navy);color:#fff9ea;box-shadow:0 7px 18px rgba(41,54,70,.16)}
.catalog-status{padding:28px;text-align:center;color:var(--muted);background:var(--paper);border:1px solid var(--line);border-radius:16px}.catalog-grid{display:grid;grid-template-columns:minmax(245px,.78fr) minmax(0,1.7fr);gap:22px;align-items:start;margin-bottom:55px}.subjects-panel,.chapters-panel{overflow:hidden;border:1px solid var(--line);border-radius:20px;background:var(--paper);box-shadow:var(--shadow)}.panel-heading{min-height:64px;padding:18px 21px;border-bottom:1px solid var(--line)}.panel-heading small{margin-left:auto;color:#938779;font-size:12px}.subject-list{display:grid;gap:7px;padding:12px}.subject-button{display:flex;flex-direction:column;align-items:flex-start;gap:6px;width:100%;padding:14px;border:1px solid transparent;border-radius:12px;background:transparent;text-align:left;color:var(--ink)}.subject-button:hover{background:#f7f2e9}.subject-button[aria-pressed="true"]{background:#f4ead8;border-color:#e6d1ae}.subject-button strong{font-size:14px;line-height:1.45}.subject-button small{font-size:11px;color:#8e8275}.selected-subject{margin:17px 21px 2px;color:var(--gold-dark);font-size:13px;font-weight:800}.chapter-list{list-style:none;margin:0;padding:12px 18px 21px;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:9px}.chapter-item{min-height:58px;border:1px solid #ede7dc;border-radius:12px;background:#fffefa}.chapter-content{display:flex;align-items:center;gap:11px;width:100%;height:100%;min-height:58px;padding:10px 12px}.chapter-item a:hover{background:#fbf5ea;border-radius:12px}.chapter-number{flex:none;width:27px;color:#ad9068;font:700 12px Georgia,serif}.chapter-title{min-width:0;flex:1;font-size:13px;line-height:1.45;font-weight:700}.access-badge{flex:none;border-radius:999px;padding:5px 8px;font-size:10px;font-weight:800;white-space:nowrap}.is-free{background:#eaf3ed;color:#476e54}.is-locked{background:#f3f0ea;color:#867a6a}.site-footer{border-top:1px solid var(--line);min-height:74px;display:flex;align-items:center;justify-content:space-between;gap:20px;color:#8e857a;font-size:12px}
@media(max-width:900px){.catalog-grid{grid-template-columns:1fr}.subject-list{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:620px){.study-shell{padding:0 15px}.site-header{height:70px}.brand-mark{width:38px;height:38px}.brand-name strong{font-size:15px}.back-link{font-size:11px;padding:8px 10px}.intro{margin:18px 0 15px;padding:24px 21px;border-radius:18px}.intro h1{font-size:25px}.intro p:last-child{font-size:12px}.eyebrow{font-size:9px}.notice{padding:12px}.notice p{font-size:11px}.catalog-section{margin:25px 0 19px}.section-heading h2,.panel-heading h2{font-size:15px}.exam-tabs{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.exam-tab{min-width:0;padding:11px 5px;font-size:12px}.catalog-grid{gap:15px;margin-bottom:34px}.subjects-panel,.chapters-panel{border-radius:15px}.panel-heading{min-height:56px;padding:15px}.subject-list{gap:5px;padding:8px}.subject-button{padding:10px}.subject-button strong{font-size:12px}.subject-button small{font-size:10px}.selected-subject{margin:13px 15px 0}.chapter-list{grid-template-columns:1fr;padding:10px 11px 14px;gap:7px}.chapter-item{min-height:52px}.chapter-title{font-size:12px}.site-footer{font-size:10px}}

.chapter-item button.chapter-content{border:0;border-radius:12px;background:transparent;color:inherit;text-align:left;cursor:pointer}
.chapter-item button.chapter-content:hover,.chapter-item a:hover{background:#fbf5ea}
.chapter-purchase-status{position:fixed;left:50%;bottom:calc(18px + env(safe-area-inset-bottom));z-index:20;transform:translateX(-50%);width:min(440px,calc(100vw - 30px));margin:0;padding:12px 15px;border:1px solid #edceb5;border-radius:12px;background:#fff1e6;color:#884b36;font-size:12px;line-height:1.5;box-shadow:0 10px 30px rgba(59,41,27,.16)}