@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Outfit:wght@400;500;600;700;800&display=swap');
:root{--ink:#1a2b44;--muted:#7c8ba0;--paper:#f6f8fc;--white:#fff;--blue:#5668ef;--blue2:#e9edff;--green:#12a585;--red:#e36368;--border:#e8edf5;--shadow:0 10px 35px rgba(31,53,93,.045)}*{box-sizing:border-box}body{margin:0;color:var(--ink);background:var(--paper);font:14px 'DM Sans',system-ui,sans-serif}button,input,textarea,select{font:inherit}button{cursor:pointer}button:disabled{opacity:.4;cursor:not-allowed}h1,h2,h3,p{margin-top:0}h1,h2,h3,.brand strong,.stat-value{font-family:Outfit,'DM Sans',sans-serif}h1{font-size:31px;margin-bottom:9px;letter-spacing:-.7px}h2{font-size:21px;letter-spacing:-.4px;margin-bottom:12px}h3{font-size:17px}p{line-height:1.75}.muted{color:var(--muted)}.small{font-size:12px}.sidebar{width:244px;background:#101d32;color:#c9d5e8;position:fixed;inset:0 auto 0 0;padding:29px 15px;display:flex;flex-direction:column;z-index:10}.brand{display:flex;gap:12px;align-items:center;padding:0 15px 37px}.brand strong{font-size:26px;color:white;letter-spacing:-1px}.brand small{display:block;color:#70849e;font-size:9px;letter-spacing:2px}.logo{background:#6474ff;color:white;border-radius:13px;padding:10px 13px;font-size:23px}.side-label{font-size:11px;letter-spacing:2px;color:#637b9a;padding:0 18px;margin-bottom:14px}.sidebar nav{display:grid;gap:5px}.sidebar nav button{border:0;background:transparent;text-align:left;color:#9aacbf;padding:14px 18px;border-radius:11px;display:flex;align-items:center;gap:15px;font-weight:600}.sidebar nav button span{font-size:20px;width:22px;text-align:center}.sidebar nav button:hover,.sidebar nav button.active{background:#25334d;color:white}.side-bottom{margin-top:auto;padding:20px 12px;color:#7890aa;font-size:11px}.side-hint{padding:15px;background:#1b2a40;border-radius:12px;line-height:1.7;color:#aabbd0;margin-bottom:15px}.main{margin-left:244px;min-height:100vh}.topbar{height:79px;border-bottom:1px solid var(--border);background:#fff;display:flex;align-items:center;justify-content:space-between;padding:0 48px;color:#728399}.top-right{display:flex;align-items:center;gap:25px}.avatar{background:#dde4ff;color:var(--blue);width:34px;height:34px;border-radius:50%;display:grid;place-items:center;font-weight:800}#menuBtn{display:none}.page{max-width:1250px;padding:39px 48px 70px;margin:auto}.eyebrow{font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:2.5px;color:#6278ef;margin-bottom:11px}.page-header{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:27px}.page-header p{margin:0;color:var(--muted)}.btn{padding:11px 18px;border-radius:10px;border:1px solid var(--border);background:white;color:var(--ink);font-weight:700;display:inline-flex;align-items:center;justify-content:center;gap:8px;text-decoration:none;transition:.15s}.btn:hover{transform:translateY(-1px);box-shadow:0 4px 16px rgba(23,41,71,.06)}.btn.primary{background:var(--blue);color:white;border-color:var(--blue)}.btn.dark{background:#14243e;color:white;border-color:#14243e}.btn.soft{background:var(--blue2);color:var(--blue);border-color:transparent}.btn.danger{color:#d94d5d;background:#fff5f5}.btn.green{background:#ecfaf5;color:#0d9b79}.btn.large{padding:14px 23px}.btn:focus-visible,.nav button:focus-visible{outline:3px solid #a6b0ff}.row{display:flex;align-items:center;gap:12px}.between{justify-content:space-between}.wrap{flex-wrap:wrap}.grid{display:grid;gap:19px}.grid.four{grid-template-columns:repeat(4,1fr)}.grid.three{grid-template-columns:repeat(3,1fr)}.grid.two{grid-template-columns:repeat(2,1fr)}.card{background:white;border:1px solid var(--border);border-radius:17px;padding:24px;box-shadow:var(--shadow)}.stat-card{position:relative;overflow:hidden;min-height:145px}.stat-label{color:var(--muted);font-size:12px;font-weight:600}.stat-value{font-size:36px;font-weight:700;letter-spacing:-1.4px;margin:17px 0 5px}.stat-symbol{position:absolute;right:22px;top:24px;font-size:24px;background:#f1f3ff;color:#6976e5;width:39px;height:39px;border-radius:12px;display:grid;place-items:center}.hero{background:#182b4c;color:white;border-radius:19px;padding:34px 37px;display:flex;justify-content:space-between;gap:20px;align-items:center;position:relative;overflow:hidden;margin-bottom:25px}.hero:after{content:'✳';font-size:220px;opacity:.07;position:absolute;right:35px;top:-100px}.hero h2{font-size:27px;margin:0 0 11px}.hero p{color:#b5c3d7;max-width:520px;margin-bottom:0}.hero .btn{z-index:1}.section-head{display:flex;justify-content:space-between;align-items:center;margin:30px 0 15px}.section-head h2{margin:0}.progress{height:9px;border-radius:20px;background:#ebeff7;overflow:hidden}.progress>div{height:100%;background:linear-gradient(90deg,#6172ef,#9b9cf6);border-radius:20px}.tag{display:inline-block;background:#edf1ff;color:#6070be;font-weight:700;border-radius:6px;font-size:11px;padding:5px 8px;margin:2px 4px 2px 0}.tag.gray{background:#f2f5f9;color:#77869b}.tag.red{background:#fff0f1;color:#cf5865}.book-card{display:flex;flex-direction:column;gap:15px;min-height:235px}.book-icon{font-size:25px;background:#f0f2ff;border-radius:13px;width:48px;height:48px;display:grid;place-items:center}.book-card h3{margin:0}.book-card p{margin:5px 0 0;font-size:12px;color:var(--muted)}.book-actions{margin-top:auto}.table-wrap{overflow:auto}.table{width:100%;border-collapse:collapse;text-align:left}.table th{font-size:11px;letter-spacing:1px;text-transform:uppercase;color:#95a0b2;border-bottom:1px solid var(--border);padding:13px}.table td{padding:15px 13px;border-bottom:1px solid #f0f3f8;vertical-align:middle}.table tr:last-child td{border-bottom:0}.table .word{font-size:17px;font-weight:700;color:var(--ink)}.search{border:1px solid var(--border);border-radius:10px;padding:11px 13px;outline:0;background:white;min-width:210px;color:var(--ink)}.search:focus{border-color:#aab3ff}.filter{background:white;border:1px solid var(--border);border-radius:10px;padding:10px}.empty{padding:50px 20px;text-align:center;color:var(--muted)}.empty .emoji{font-size:47px;margin-bottom:15px}.empty h3{color:var(--ink)}.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px}.field{display:flex;flex-direction:column;gap:7px;font-weight:700;font-size:12px}.field input,.field textarea,.field select{width:100%;border:1px solid #dfe5ef;background:white;border-radius:10px;padding:11px;color:var(--ink);outline:0;font-weight:400}.field textarea{min-height:90px;resize:vertical}.field input:focus,.field textarea:focus{border-color:var(--blue)}.field.full{grid-column:1/-1}.modal-root{position:fixed;inset:0;background:rgba(17,29,49,.55);display:flex;align-items:center;justify-content:center;padding:15px;z-index:30}.hidden{display:none!important}.modal{width:min(720px,100%);max-height:90vh;overflow-y:auto;background:white;border-radius:18px;padding:26px;box-shadow:0 25px 90px #15254442}.modal-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:22px}.close{border:0;background:#f2f5fa;border-radius:8px;padding:7px 11px}.modal-footer{display:flex;justify-content:flex-end;gap:10px;margin-top:22px}.session-card{max-width:760px;margin:0 auto;text-align:center;padding:38px}.session-head{display:flex;justify-content:space-between;color:var(--muted);font-size:12px;margin-bottom:22px}.big-word{font:700 49px Outfit,sans-serif;margin:27px 0 7px;letter-spacing:-1px}.phonetic{color:#7c8caa}.definition{text-align:left;background:#f7f9fe;border-radius:12px;padding:21px;margin:22px 0;line-height:1.7}.example{font-style:italic;color:#485973;line-height:1.8;margin:18px auto;max-width:550px}.word-img{width:min(100%,360px);max-height:210px;object-fit:cover;border-radius:12px;margin-top:14px}.answer-buttons{display:flex;gap:12px;justify-content:center;margin-top:22px}.answer-buttons .btn{min-width:155px}.overview-note{padding:15px 17px;background:#eff2ff;border-radius:11px;color:#5766a0;line-height:1.7}.chart-bars{display:flex;gap:10px;align-items:end;height:160px;border-bottom:1px solid var(--border);padding:0 5px}.chart-bars>div{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:end;height:100%;gap:8px}.bar{width:55%;max-width:35px;min-height:2px;background:linear-gradient(#7c89f5,#5668ed);border-radius:6px 6px 0 0}.chart-label{font-size:11px;color:var(--muted)}.list-info{display:flex;gap:14px;align-items:center;justify-content:space-between;border-bottom:1px solid var(--border);padding:13px 0}.list-info:last-child{border:0}#toast{position:fixed;right:22px;bottom:22px;background:#172945;color:white;padding:14px 22px;border-radius:11px;opacity:0;transform:translateY(10px);transition:.2s;z-index:70;pointer-events:none}#toast.show{opacity:1;transform:translateY(0)}.warning{background:#fff9e8;color:#8d6c25;border-radius:10px;padding:13px 15px;line-height:1.7}.pill{padding:4px 9px;border-radius:50px;background:#eaf8f3;color:#168e74;font-size:11px;font-weight:700}@media(max-width:1050px){.page{padding:30px 25px}.topbar{padding:0 25px}.grid.four{grid-template-columns:repeat(2,1fr)}}@media(max-width:760px){.sidebar{transform:translateX(-100%);transition:.2s}.sidebar.open{transform:translateX(0)}.main{margin:0}.topbar{height:65px}#menuBtn{display:block;background:none;border:0;font-size:22px;color:var(--ink)}.page{padding:25px 17px}.grid.two,.grid.three,.grid.four{grid-template-columns:1fr}.hero{padding:26px;align-items:flex-start;flex-direction:column}.page-header{align-items:flex-start;flex-direction:column}.top-right{gap:9px}.form-grid{grid-template-columns:1fr}.big-word{font-size:37px}.session-card{padding:22px}.answer-buttons{flex-direction:column}.answer-buttons .btn{width:100%}.modal{padding:19px}}

/* v1.3: confusion recommendation panel */
.confusion-section{border:1px solid var(--line,#dfe5ee);border-radius:14px;padding:16px;margin-top:16px;background:rgba(100,116,139,.045)}
.confusion-section h3{margin:0 0 8px;font-size:17px}
.confusion-item{padding:12px 0;border-top:1px solid rgba(100,116,139,.2)}
.confusion-item p{margin:8px 0 10px;line-height:1.6}
.confusion-item .btn{padding:6px 9px;font-size:12px}

/* v1.5: dedicated learning navigation and vocabulary details */
.study-nav{display:flex;justify-content:space-between;gap:12px;margin-top:25px;flex-wrap:wrap}.study-nav .btn{min-width:145px}
.full-word-info{margin:22px 0;text-align:left}.sense-group{padding:20px 22px;background:#f7f9fe;border-radius:13px;margin:13px 0}.sense-list{padding-left:23px;line-height:1.8;margin:6px 0 0}.sense-list li{padding:3px 0}.example-line{font-style:italic;color:#435773;margin:10px 0;line-height:1.8}.source-links{display:flex;gap:9px;flex-wrap:wrap;margin-top:18px}.source-links .btn{font-size:12px;padding:8px 10px}.word-link{font-size:17px;font-weight:700;color:#465bd5;border:0;background:transparent;padding:0;text-align:left;cursor:pointer}.word-link:hover{text-decoration:underline}.detail-heading{display:flex;gap:14px;align-items:center;flex-wrap:wrap}.detail-heading h1{margin:0}.detail-meta{background:#f7f9fe;border-radius:12px;padding:15px;display:grid;grid-template-columns:1fr 1fr;gap:10px;color:#617087;font-size:12px}
@media(max-width:760px){.study-nav .btn{flex:1;min-width:110px}.detail-meta{grid-template-columns:1fr}.sense-group{padding:16px}.source-links .btn{flex:1}}