:root{
  --primary:#1967d2;
  --primary-dark:#104a9b;
  --primary-soft:#eaf2ff;
  --bg:#edf3fb;
  --surface:#ffffff;
  --surface-soft:#f8fbff;
  --line:#d5e0ef;
  --text:#142033;
  --muted:#617087;
  --ok:#087f5b;
  --ok-bg:#eefbf6;
  --warn:#9a6700;
  --warn-bg:#fff8dc;
  --danger:#b42318;
  --danger-bg:#fff2f1;
  --shadow:0 6px 18px rgba(15,23,42,.08);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;min-height:100vh;font-family:"Segoe UI",Arial,sans-serif;background:var(--bg);color:var(--text);line-height:1.55}
button,input{font:inherit}
button{touch-action:manipulation}
a{color:var(--primary-dark)}
[hidden]{display:none!important}

.site-header{height:50px;background:var(--primary);color:#fff;display:flex;align-items:center;justify-content:space-between;gap:16px;padding:0 18px;box-shadow:0 2px 8px #0002;position:relative;z-index:50}
.site-header .module-back{display:inline-flex;align-items:center;justify-content:center;color:#fff;text-decoration:none;font-size:13px;font-weight:900;white-space:nowrap;border:1px solid rgba(255,255,255,.38);background:rgba(255,255,255,.14);border-radius:999px;padding:6px 10px}
.site-header .module-back:hover{background:rgba(255,255,255,.24)}
.site-header>strong{font-size:15px}
#backToSeries{display:none}

.series-home{max-width:1080px;margin:0 auto;padding:34px 18px 46px}
.intro-card{background:var(--surface);border:1px solid var(--line);border-radius:18px;padding:28px;box-shadow:var(--shadow);margin-bottom:22px}
.eyebrow{display:inline-block;background:var(--primary-soft);border:1px solid #bfd5f5;color:var(--primary-dark);border-radius:999px;padding:5px 10px;font-size:12px;font-weight:800;margin-bottom:10px}
.intro-card h1{font-size:34px;line-height:1.1;color:var(--primary-dark);margin:0 0 9px}
.intro-card p{max-width:820px;font-size:16px;margin:0}
.series-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
.series-card{min-height:165px;border:1px solid var(--line);border-radius:16px;background:var(--surface);padding:22px;text-align:left;display:flex;flex-direction:column;justify-content:flex-end;gap:6px;box-shadow:var(--shadow)}
.series-card.active{cursor:pointer;background:linear-gradient(135deg,#fff,#edf5ff);border-color:#b9d3f6;transition:.18s ease}
.series-card.active:hover{transform:translateY(-2px);box-shadow:0 10px 24px rgba(25,103,210,.14)}
.series-card.disabled{opacity:.58}
.series-label{font-size:24px;font-weight:900;color:var(--primary-dark)}
.series-card strong{color:var(--primary);font-size:15px}

.course-view{height:calc(100vh - 50px);height:calc(100dvh - 50px);min-height:0;overflow:hidden}
.course-toolbar{height:48px;background:var(--surface);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:8px;padding:7px 14px;position:relative;z-index:45}
.pill-button,.series-pill{border-radius:999px;padding:7px 13px;font-size:12.5px;font-weight:800;white-space:nowrap}
.pill-button{border:1px solid #bdd2ef;background:#fff;color:var(--primary-dark);cursor:pointer}
.pill-button:hover{background:var(--primary-soft)}
.series-pill{background:var(--primary);color:#fff;border:1px solid var(--primary)}
.menu-toggle{display:none;margin-left:auto}
.course-layout{height:calc(100vh - 98px);height:calc(100dvh - 98px);display:grid;grid-template-columns:260px 1fr;min-width:0;min-height:0}
.lesson-menu{background:#fff;border-right:1px solid var(--line);overflow-y:auto;padding:10px 8px}
.menu-group-title{font-size:10px;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:900;padding:10px 8px 5px}
.menu-item{width:100%;display:block;border:0;background:transparent;text-align:left;color:#172033;font-size:12.5px;font-weight:700;line-height:1.25;padding:9px;border-radius:8px;margin:2px 0;cursor:pointer}
.menu-item:hover{background:var(--primary-soft);color:var(--primary-dark)}
.menu-item.active{background:var(--primary);color:#fff;box-shadow:0 2px 7px rgba(25,103,210,.28)}
.menu-item.pending{cursor:default;color:#8b96a8}
.menu-item.pending:hover{background:transparent;color:#8b96a8}
.content-area{padding:13px;overflow:hidden;min-width:0;min-height:0}
.lesson-heading{min-height:70px;display:flex;align-items:flex-start;justify-content:space-between;gap:18px;margin-bottom:9px}
.lesson-heading h2{font-size:24px;line-height:1.15;color:var(--primary-dark);margin:2px 0 0}
.unit-name{font-size:11px;font-weight:900;color:var(--primary);text-transform:uppercase;letter-spacing:.06em}
.technical-title{font-size:12px;font-weight:800;color:var(--muted);margin-top:2px}
.lesson-objective{font-size:13px;line-height:1.4;max-width:500px;text-align:right;margin:2px 0 0}
.lesson-content{height:calc(100vh - 203px);height:calc(100dvh - 203px);overflow-y:auto;overscroll-behavior:contain;background:var(--surface);border:1px solid var(--line);border-radius:13px;padding:24px;box-shadow:var(--shadow)}
.lesson-content h3{font-size:21px;color:var(--primary-dark);margin:24px 0 8px}
.lesson-content h3:first-child{margin-top:0}
.lesson-content p{margin:7px 0}
.lesson-content strong{font-weight:800}

.hero-box,.note-box,.ok-box,.concept-box{border-radius:12px;padding:15px 16px;margin:14px 0}
.hero-box{background:linear-gradient(135deg,var(--primary-soft),#fff);border:1px solid #bdd4f4}
.note-box{background:var(--warn-bg);border-left:5px solid #d59b00}
.ok-box{background:var(--ok-bg);border-left:5px solid var(--ok)}
.concept-box{background:var(--surface-soft);border:1px solid var(--line)}
.card-title{display:block;color:var(--primary-dark);font-weight:900;margin-bottom:5px}

.diagnostic-intro{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:14px 0}
.diagnostic-intro .mini-card{background:#fff;border:1px solid var(--line);border-radius:11px;padding:13px}
.diagnostic-intro .mini-card strong{display:block;color:var(--primary-dark);margin-bottom:4px}
.quiz-item{border:1px solid var(--line);border-radius:11px;padding:14px;margin:11px 0;background:#fff}
.quiz-item>p{font-weight:800;margin:0 0 8px}
.quiz-item label{display:flex;align-items:flex-start;gap:8px;padding:7px 8px;border-radius:8px;cursor:pointer}
.quiz-item label:hover{background:var(--surface-soft)}
.quiz-item input{margin-top:4px}
.quiz-item.is-unscored{border-left:5px solid #6d4aff;background:#fbfaff}
.quiz-item .question-tag{display:inline-block;margin-bottom:7px;border-radius:999px;padding:3px 7px;background:#f1edff;color:#5d42bd;font-size:10px;font-weight:900;text-transform:uppercase;letter-spacing:.04em}
.quiz-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px}
.action-button{border:1px solid #b9d3f6;background:#fff;color:var(--primary-dark);font-weight:800;border-radius:8px;padding:10px 13px;cursor:pointer}
.action-button.primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.action-button.success{background:var(--ok);color:#fff;border-color:var(--ok)}
.action-button:hover{filter:brightness(.98)}
.quiz-result{margin-top:14px}
.result-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin:11px 0}
.result-card{border:1px solid var(--line);border-radius:10px;background:#fff;padding:12px}
.result-card strong{display:block;color:var(--primary-dark);margin-bottom:4px}

.review-panel{margin:16px 0;border:1px solid var(--line);border-radius:12px;background:var(--surface-soft);padding:14px}
.review-panel>h3{margin-top:0}
.review-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.review-card{background:#fff;border:1px solid var(--line);border-radius:10px;padding:13px}
.review-card strong{display:block;color:var(--primary-dark);margin-bottom:5px}
.review-card .practice{margin-top:8px;padding-top:8px;border-top:1px dashed #cbd6e5}
.review-card .practice span{font-weight:800;color:var(--primary-dark)}
.review-method{margin-bottom:12px}

.physics-graph{width:100%;max-width:620px;height:auto;display:block;margin:12px auto}
.graph-axis{stroke:#607089;stroke-width:2}
.graph-grid{stroke:#dbe4ef;stroke-width:1}
.graph-line{stroke:#1967d2;stroke-width:4;fill:none}
.graph-point{fill:#1967d2}
.graph-text{fill:#4b5b72;font-size:12px}
.graph-label{fill:#104a9b;font-size:13px;font-weight:700}

.pending-box{border:1px dashed #b9c7d8;border-radius:12px;background:#f8fafc;padding:16px;color:var(--muted)}
.pending-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;margin-top:10px}
.pending-chip{border:1px solid var(--line);border-radius:9px;background:#fff;padding:9px 10px;font-size:12px;font-weight:800;color:#68758a}

@media(max-width:900px){
  .menu-toggle{display:inline-block}
  .course-layout{display:block;height:calc(100vh - 98px);height:calc(100dvh - 98px);min-height:0}
  .lesson-menu{display:none;position:fixed;inset:98px 0 0 0;z-index:40;border-right:0;padding:12px;overflow:auto}
  .lesson-menu.open{display:block}
  .content-area{height:100%;display:flex;flex-direction:column;overflow:hidden;padding:10px}
  .lesson-heading{flex:0 0 auto;min-height:0;flex-direction:column;gap:3px;margin-bottom:10px}
  .lesson-objective{max-width:none;text-align:left}
  .lesson-content{flex:1 1 auto;height:auto;min-height:0;overflow-y:auto;-webkit-overflow-scrolling:touch}
}
@media(max-width:720px){
  .site-header{padding:0 10px}
  .site-header .module-back{font-size:12px;padding:5px 9px}
  .site-header>strong{font-size:13px}
  .series-home{padding:18px 10px 30px}
  .intro-card{padding:20px}
  .intro-card h1{font-size:27px}
  .series-grid,.diagnostic-intro,.review-grid,.result-grid,.pending-list{grid-template-columns:1fr}
  .series-card{min-height:125px}
  .course-toolbar{padding:6px 8px}
  .content-area{padding:8px}
  .lesson-heading h2{font-size:20px}
  .lesson-content{padding:16px;border-radius:10px}
  .lesson-content h3{font-size:19px}
}