.study-root{--l-bg:#f5f6fc;--l-card:#fff;--l-ink:#1a1e3a;--l-muted:#565b7c;--l-line:#dfe3f2;--l-accent:#4f46e5;--l-accent-dark:#3730a3;--l-accent-ink:#fff;--l-accent-soft:#eceeff;--l-good:#0b7a43;--l-good-soft:#e3f7ec;--l-bad:#a4380d;--l-bad-soft:#fff0e6;--l-gold:#b7791f;--l-gold-soft:#fff6db;background:var(--l-bg);min-height:100dvh;color:var(--l-ink);font-family:Pretendard,Plus Jakarta Sans,Noto Sans KR,system-ui,sans-serif;line-height:1.55}.study-root[data-site=english]{--l-accent:#047857;--l-accent-dark:#065f46;--l-accent-soft:#e2f6ee}.study-root :focus-visible{outline:3px solid var(--l-accent);outline-offset:2px;border-radius:8px}.l-wrap{width:100%;max-width:720px;margin:0 auto;padding:16px}.l-wrap-wide{max-width:1040px}.l-sr{clip:rect(0 0 0 0);white-space:nowrap;width:1px;height:1px;position:absolute;overflow:hidden}.l-skip{position:absolute;left:-9999px}.l-skip:focus{z-index:100;background:#fff;border-radius:8px;padding:8px 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80ms;display:inline-flex}.l-btn:hover{filter:brightness(1.06)}.l-btn:active{box-shadow:0 1px 0 var(--l-accent-dark);transform:translateY(3px)}.l-btn[disabled]{opacity:.5;cursor:not-allowed;box-shadow:none;transform:none}.l-btn-block{width:100%;display:flex}.l-btn-ghost{color:var(--l-accent-dark);border:2px solid var(--l-line);box-shadow:0 3px 0 var(--l-line);background:#fff}.l-btn-ghost:active{box-shadow:0 0 0 var(--l-line)}.l-btn-light{color:var(--l-accent-dark);background:#fff;box-shadow:0 4px #0003}.l-link{color:var(--l-accent-dark);cursor:pointer;background:0 0;border:0;min-height:44px;padding:8px 4px;font-weight:700;text-decoration:underline}.l-chip{background:var(--l-accent-soft);color:var(--l-accent-dark);cursor:pointer;border:0;border-radius:999px;align-items:center;gap:6px;min-height:40px;padding:8px 12px;font-size:.85rem;font-weight:700;display:inline-flex}.l-input{border:2px solid var(--l-line);width:100%;min-height:56px;color:var(--l-ink);background:#fff;border-radius:16px;padding:12px 16px;font-size:1.25rem;font-weight:700}.l-input:focus{border-color:var(--l-accent)}.l-options{gap:10px;display:grid}.l-option{text-align:left;border:2px solid var(--l-line);width:100%;min-height:56px;color:var(--l-ink);cursor:pointer;box-shadow:0 3px 0 var(--l-line);background:#fff;border-radius:16px;align-items:center;gap:12px;padding:12px 14px;font-size:1.05rem;font-weight:600;display:flex}.l-option[data-selected=true]{border-color:var(--l-accent);background:var(--l-accent-soft);box-shadow:0 3px 0 var(--l-accent)}.l-option[disabled]{cursor:default}.l-option-key{background:var(--l-accent-soft);width:32px;height:32px;color:var(--l-accent-dark);border-radius:10px;flex:none;place-items:center;font-weight:900;display:grid}.l-slots{flex-wrap:wrap;gap:8px;margin:12px 0;padding:0;list-style:none;display:flex}.l-slot{border-bottom:3px solid var(--l-line);min-width:64px;min-height:48px;padding:8px 12px;font-size:1.1rem;font-weight:800}.l-tokens{flex-wrap:wrap;gap:8px;margin-bottom:8px;display:flex}.l-token{border:2px solid var(--l-line);min-height:48px;box-shadow:0 3px 0 var(--l-line);cursor:pointer;background:#fff;border-radius:14px;padding:8px 16px;font-size:1.05rem;font-weight:800}.l-token[disabled]{opacity:.35;box-shadow:none}.l-bar{background:var(--l-line);border-radius:999px;height:14px;overflow:hidden}.l-bar>span{background:var(--l-accent);border-radius:999px;height:100%;transition:width .4s;display:block}.l-bar-gold>span{background:#f5b301}.l-topbar{z-index:20;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-bottom:2px solid var(--l-line);background:#f5f6fceb;position:sticky;top:0}.l-topbar-inner{justify-content:space-between;align-items:center;gap:12px;max-width:1040px;margin:0 auto;padding:10px 16px;display:flex}.l-brand{letter-spacing:-.02em;color:var(--l-accent-dark);align-items:center;font-size:1.05rem;font-weight:900;line-height:0;text-decoration:none;display:inline-flex}.l-logo{border-radius:10px;width:auto;height:44px;display:block}.l-stats{align-items:center;gap:8px;display:flex}.l-stat{border:2px solid var(--l-line);background:#fff;border-radius:999px;align-items:center;gap:4px;padding:6px 10px;font-size:.9rem;font-weight:800;display:inline-flex}.l-tabs{z-index:30;border-top:2px solid var(--l-line);padding-bottom:env(safe-area-inset-bottom);background:#fff;display:flex;position:fixed;bottom:0;left:0;right:0}.l-tab{min-height:60px;color:var(--l-muted);flex-direction:column;flex:1;align-items:center;gap:2px;padding:8px 4px;font-size:.78rem;font-weight:700;text-decoration:none;display:flex}.l-tab[aria-current=page]{color:var(--l-accent-dark)}.l-tab[aria-current=page] .l-tab-ico{background:var(--l-accent-soft)}.l-tab-ico{border-radius:12px;place-items:center;width:44px;height:30px;font-size:1.3rem;display:grid}.l-main{padding-bottom:96px}@media (min-width:900px){.l-tabs{background:0 0;border:0;gap:8px;max-width:1040px;margin:0 auto;padding:8px 16px 0;position:static}.l-tab{border-radius:14px;flex-direction:row;flex:none;justify-content:center;min-height:44px;padding:8px 16px;font-size:.95rem}.l-main{padding-bottom:32px}}.l-panel{border:2px solid;border-radius:20px;padding:16px}.l-panel-good{background:var(--l-good-soft);color:#06492a;border-color:#7ed4a5}.l-panel-hint{background:var(--l-gold-soft);color:#5c3d06;border-color:#f0cf7a}.l-panel-reveal{background:var(--l-bad-soft);color:#5a1f05;border-color:#f2b58f}.l-panel-title{align-items:center;gap:8px;margin-bottom:6px;font-weight:900;display:flex}.l-path{gap:12px;margin:0;padding:0;list-style:none;display:grid}.l-node{border:2px solid var(--l-line);color:inherit;background:#fff;border-radius:20px;align-items:center;gap:14px;padding:14px;text-decoration:none;display:flex}.l-node[data-status=current]{border-color:var(--l-accent);box-shadow:0 4px 0 var(--l-accent)}.l-node[data-status=locked]{opacity:.6}.l-node-ico{background:var(--l-accent-soft);border-radius:18px;flex:none;place-items:center;width:52px;height:52px;font-size:1.5rem;display:grid}.l-node[data-status=done] .l-node-ico{background:var(--l-good-soft)}.l-math-fallback{font-style:italic}.l-mathblock{padding:10px 0;font-size:1.2rem;overflow-x:auto}.l-math .katex{font-size:1.08em}.l-qprompt{font-size:1.2rem;font-weight:700;line-height:1.6}.l-pop{animation:.35s l-pop}@keyframes l-pop{0%{opacity:0;transform:scale(.8)}70%{transform:scale(1.06)}to{opacity:1;transform:scale(1)}}.l-rise{animation:.9s forwards l-rise}@keyframes l-rise{0%{opacity:0;transform:translateY(6px)}30%{opacity:1}to{opacity:0;transform:translateY(-14px)}}@media (prefers-reduced-motion:reduce){.study-root *,.study-root :before,.study-root :after{transition:none!important;animation:none!important}}.l-landing-head{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px 12px;display:flex}.l-locale{border:2px solid var(--l-line);background:#fff;border-radius:999px;align-items:center;gap:6px;max-width:100%;padding:3px 3px 3px 12px;display:inline-flex}.l-locale-select{max-width:min(60vw,260px);min-height:44px;color:var(--l-accent-dark);font:inherit;cursor:pointer;text-overflow:ellipsis;background:0 0;border:0;border-radius:999px;padding:6px 12px;font-weight:800}.l-locale-select:focus-visible{outline:3px solid var(--l-accent);outline-offset:2px}.l-locale[data-compact] .l-locale-select{min-height:40px;font-size:.9rem}.l-locale[aria-busy=true]{opacity:.7}.l-target{background:var(--l-soft,#f5f3ff);border-radius:16px;flex-wrap:wrap;align-items:center;gap:10px 14px;padding:14px 16px;display:flex}.l-target-text{overflow-wrap:anywhere;font-size:clamp(1.6rem,6vw,2.4rem);font-weight:800;line-height:1.3}.l-target-rr{color:var(--l-muted,#475569);flex-basis:100%;font-size:1rem}.l-target-note{color:var(--l-muted,#475569);flex-basis:100%;font-size:.85rem}.l-grades{grid-template-columns:repeat(3,minmax(0,1fr))}.l-grade{text-align:center;overflow-wrap:anywhere;justify-content:center;min-height:52px;padding-inline:6px}@media (min-width:720px){.l-grades{grid-template-columns:repeat(6,minmax(0,1fr))}}.l-tier{vertical-align:middle;border-radius:999px;margin-inline-start:4px;padding:1px 8px;font-size:.75rem;font-weight:800;display:inline-block}.l-tier[data-tier=free]{color:#166534;background:#dcfce7}.l-tier[data-tier=premium]{color:#5b21b6;background:#ede9fe}.l-premium-gate{text-align:center}.l-premium-gate .l-btn[disabled]{opacity:.6;cursor:not-allowed}