/* ═══════════════════════════════════════════════════
   Mathe Lernhilfe KA8 – Modern Stylesheet 2026
   ═══════════════════════════════════════════════════ */
@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@400;500;600;700;800;900&family=JetBrains+Mono:wght@400;600&display=swap');

:root {
  --bg:#F1F3F8; --surface:#FFFFFF; --border:#E4E7EC; --border-2:#D0D5DD;
  --dark:#101828; --text:#344054; --gray:#667085; --lgray:#E4E7EC;
  --blue:#1D5DCA; --blue-d:#0D3D8E; --blue-l:#EFF6FF; --blue-m:#BFD9FF;
  --green:#067647; --green-l:#ECFDF3; --green-m:#ABEFC6;
  --orange:#C4320A; --orange-l:#FEF6EE; --orange-m:#F9DBAF;
  --purple:#5925DC; --purple-l:#F4F3FF; --purple-m:#D9D6FE;
  --teal:#0E7090; --teal-l:#F0FAFB; --teal-m:#A5E5F0;
  --yellow:#B54708; --yellow-l:#FFFAEB; --yellow-m:#FEDF89;
  --red:#B42318; --red-l:#FEF3F2; --red-m:#FECDCA;
  --header:#0C1B33;
  --radius:14px; --radius-sm:8px;
  --shadow-sm:0 1px 3px rgba(16,24,40,.07),0 1px 2px rgba(16,24,40,.04);
  --shadow:0 4px 16px rgba(16,24,40,.08),0 1px 4px rgba(16,24,40,.04);
  --shadow-lg:0 12px 32px rgba(16,24,40,.11),0 2px 8px rgba(16,24,40,.06);
  --t:.18s cubic-bezier(.4,0,.2,1);
}

*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-font-smoothing:antialiased}
body{font-family:'Outfit',sans-serif;color:var(--text);background:var(--bg);font-size:17px;line-height:1.7;min-height:100vh}
body::before{content:'';position:fixed;inset:0;background-image:radial-gradient(circle,rgba(0,0,0,.04) 1px,transparent 1px);background-size:28px 28px;pointer-events:none;z-index:-1}

.container{max-width:980px;margin:0 auto;padding:0 20px}
.page-wrap{padding:28px 0 72px}

h1{font-size:28px;font-weight:900;color:var(--dark);letter-spacing:-.6px}
h2{font-size:21px;font-weight:800;color:var(--dark);margin:32px 0 12px;letter-spacing:-.3px}
h3{font-size:18px;font-weight:700;color:var(--dark);margin:22px 0 8px}
p{margin:6px 0}
ul,ol{padding-left:20px;margin:6px 0}
li{margin:4px 0}
strong{font-weight:700;color:var(--dark)}

/* ── Header ── */
.site-header{background:var(--header);padding:14px 0;position:sticky;top:0;z-index:100;border-bottom:1px solid rgba(255,255,255,.06);box-shadow:0 4px 24px rgba(0,0,0,.28)}
.site-header .container{display:flex;align-items:center;justify-content:space-between;gap:12px}
.header-title{font-size:18px;font-weight:900;letter-spacing:-.3px;color:white}
.header-title a{color:white;text-decoration:none}
.header-subtitle{font-size:13.5px;color:rgba(255,255,255,.45);margin-top:1px;font-weight:500}
.countdown{background:rgba(255,255,255,.09);border:1px solid rgba(255,255,255,.14);border-radius:20px;padding:6px 14px;font-size:14px;font-weight:700;color:white;white-space:nowrap}

/* ── Breadcrumb ── */
.breadcrumb{font-size:14.5px;color:var(--gray);margin:18px 0 0;display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.breadcrumb a{color:var(--blue);text-decoration:none;font-weight:600}
.breadcrumb a:hover{text-decoration:underline}
.breadcrumb-sep{color:var(--border-2);font-size:16px}

/* ── Topic Grid ── */
.topic-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:14px;margin:16px 0}

.topic-card{
  background:var(--surface);border-radius:var(--radius);border:1px solid var(--border);
  box-shadow:var(--shadow-sm);padding:20px;display:flex;flex-direction:column;gap:12px;
  transition:var(--t);position:relative;overflow:hidden
}
.topic-card::before{content:'';position:absolute;top:0;left:0;right:0;height:3px}
.topic-card:hover{box-shadow:var(--shadow);transform:translateY(-3px)}
.topic-card.blue::before  {background:linear-gradient(90deg,var(--blue),#60a5fa)}
.topic-card.green::before {background:linear-gradient(90deg,var(--green),#34d399)}
.topic-card.orange::before{background:linear-gradient(90deg,var(--orange),#fb923c)}
.topic-card.purple::before{background:linear-gradient(90deg,var(--purple),#a78bfa)}
.topic-card.teal::before  {background:linear-gradient(90deg,var(--teal),#22d3ee)}
.topic-card.yellow::before{background:linear-gradient(90deg,var(--yellow),#fbbf24)}

.topic-card-title{font-size:16.5px;font-weight:800;color:var(--dark);display:flex;align-items:center;gap:8px;letter-spacing:-.2px}
.topic-card-desc{font-size:14.5px;color:var(--gray);line-height:1.55}

/* ── Ampel ── */
.ampel{display:flex;gap:5px;align-items:center}
.ampel-label{font-size:13px;color:var(--gray);font-weight:700;margin-right:4px;text-transform:uppercase;letter-spacing:.6px}
.ampel-btn{border:2px solid transparent;border-radius:50%;width:32px;height:32px;cursor:pointer;font-size:14px;transition:var(--t);opacity:.25;background:none}
.ampel-btn:hover{opacity:.65;transform:scale(1.1)}
.ampel-btn.active{opacity:1;transform:scale(1.15);box-shadow:0 0 0 3px rgba(0,0,0,.1)}
.ampel-btn.rot  {background:#ef4444;color:white;border-color:#ef4444}
.ampel-btn.gelb {background:#f59e0b;color:white;border-color:#f59e0b}
.ampel-btn.gruen{background:#10b981;color:white;border-color:#10b981}

/* ── Section header ── */
.section-header{display:flex;align-items:center;gap:14px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px 22px;margin:32px 0 16px;box-shadow:var(--shadow-sm)}
.section-icon{font-size:26px}
.section-title{font-size:18px;font-weight:800;color:var(--dark);letter-spacing:-.3px}
.section-sub{font-size:14px;color:var(--gray);margin-top:2px}
.section-points{margin-left:auto;background:var(--yellow-l);color:var(--yellow);border:1.5px solid var(--yellow-m);border-radius:20px;padding:5px 16px;font-size:13.5px;font-weight:700;white-space:nowrap}

/* ── Content boxes ── */
.box{border-radius:var(--radius-sm);padding:14px 18px;margin:12px 0;border:1px solid}
.box-blue  {background:var(--blue-l);  border-color:var(--blue-m)}
.box-green {background:var(--green-l); border-color:var(--green-m)}
.box-orange{background:var(--orange-l);border-color:var(--orange-m)}
.box-purple{background:var(--purple-l);border-color:var(--purple-m)}
.box-yellow{background:var(--yellow-l);border-color:var(--yellow-m)}
.box-red   {background:var(--red-l);   border-color:var(--red-m)}
.box-teal  {background:var(--teal-l);  border-color:var(--teal-m)}

.box-title{font-weight:800;font-size:14px;margin-bottom:5px;text-transform:uppercase;letter-spacing:.6px}
.box-title.blue  {color:var(--blue)}
.box-title.green {color:var(--green)}
.box-title.orange{color:var(--orange)}
.box-title.purple{color:var(--purple)}
.box-title.teal  {color:var(--teal)}
.box-title.red   {color:var(--red)}

/* ── Formula ── */
.formula{background:var(--blue-l);border:1.5px solid var(--blue-m);border-radius:var(--radius-sm);padding:14px 22px;margin:14px 0;text-align:center;font-size:20px;font-weight:800;color:var(--blue);font-family:'JetBrains Mono','Courier New',monospace}

/* ── Steps ── */
.steps{display:flex;flex-direction:column;gap:8px;margin:12px 0}
.step{display:flex;gap:14px;align-items:flex-start;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:11px 16px;box-shadow:var(--shadow-sm)}
.step-num{background:var(--blue);color:white;border-radius:50%;width:28px;height:28px;min-width:28px;display:flex;align-items:center;justify-content:center;font-weight:800;font-size:13px;margin-top:2px}
.step-content{flex:1;font-size:16px;color:var(--text)}

/* ── Tables ── */
table.tbl{width:100%;border-collapse:collapse;margin:12px 0;font-size:15px;border-radius:var(--radius-sm);overflow:hidden;border:1px solid var(--border);box-shadow:var(--shadow-sm)}
table.tbl th{background:var(--header);color:white;padding:10px 14px;text-align:center;font-weight:700;font-size:14.5px;letter-spacing:.3px}
table.tbl td{border:1px solid var(--border);padding:8px 14px;text-align:center}
table.tbl tr:nth-child(even) td{background:#FAFBFD}
table.tbl tr:hover td{background:var(--blue-l)}

table.wt{border-collapse:collapse;margin:10px auto;font-size:15px}
table.wt th{background:var(--header);color:white;padding:7px 18px;border:2px solid var(--header);font-weight:700;font-family:'JetBrains Mono',monospace}
table.wt td{border:2px solid var(--border);padding:7px 18px;text-align:center;background:var(--blue-l);min-width:44px;font-family:'JetBrains Mono',monospace;font-weight:600}
table.wt td.leer{background:white;color:transparent}

/* ── Exercise blocks ── */
.aufgabe{background:var(--orange-l);border:1.5px solid var(--orange-m);border-radius:var(--radius);padding:16px 20px;margin:16px 0}
.aufgabe-header{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:10px;flex-wrap:wrap}
.aufgabe-title{font-weight:800;color:var(--orange);font-size:15.5px;letter-spacing:-.2px}
.aufgabe-level{font-size:13px;padding:3px 10px;border-radius:20px;font-weight:700;border:1.5px solid}
.level-easy  {background:var(--green-l); color:var(--green); border-color:var(--green-m)}
.level-medium{background:var(--yellow-l);color:var(--yellow);border-color:var(--yellow-m)}
.level-hard  {background:var(--red-l);   color:var(--red);   border-color:var(--red-m)}

/* ── Solution toggle ── */
.solution-wrap{margin-top:12px}
.btn-solution{background:var(--dark);color:white;border:none;border-radius:var(--radius-sm);padding:9px 18px;font-size:15px;font-weight:700;cursor:pointer;display:inline-flex;align-items:center;gap:8px;font-family:'Outfit',sans-serif;transition:var(--t);letter-spacing:.2px}
.btn-solution:hover{background:#1e2d40;transform:translateY(-1px);box-shadow:var(--shadow)}
.solution-box{display:none;background:var(--green-l);border:1.5px solid var(--green-m);border-radius:var(--radius-sm);padding:14px 18px;margin-top:10px;font-size:15.5px;animation:fadeIn .2s ease}
.solution-box.visible{display:block}
@keyframes fadeIn{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:translateY(0)}}
.solution-label{font-weight:800;color:var(--green);font-size:13.5px;margin-bottom:7px;text-transform:uppercase;letter-spacing:.6px}

/* ── Code blocks ── */
.calc{background:#0C1B33;color:#e2e8f0;border-radius:var(--radius-sm);padding:12px 18px;margin:10px 0;font-family:'JetBrains Mono','Courier New',monospace;font-size:14px;line-height:1.85;overflow-x:auto;white-space:pre-wrap;word-break:break-word}

/* ── Grids ── */
.two-col  {display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:12px 0}
.three-col{display:grid;grid-template-columns:1fr 1fr 1fr;gap:12px;margin:12px 0}
@media(max-width:640px){
  .two-col,.three-col{grid-template-columns:1fr}
  .topic-grid{grid-template-columns:1fr}
  h1{font-size:24px}
  .section-points{display:none}
}

/* ── Buttons ── */
.btn{display:inline-flex;align-items:center;gap:8px;border-radius:var(--radius-sm);padding:12px 24px;font-size:16px;font-weight:700;text-decoration:none;cursor:pointer;border:none;font-family:'Outfit',sans-serif;transition:var(--t);letter-spacing:.2px}
.btn-primary{background:var(--blue);color:white;box-shadow:0 1px 2px rgba(29,93,202,.3)}
.btn-primary:hover{background:var(--blue-d);transform:translateY(-1px);box-shadow:0 4px 12px rgba(29,93,202,.35)}
.btn-back{background:var(--surface);color:var(--text);border:1.5px solid var(--border)}
.btn-back:hover{background:var(--bg);border-color:var(--border-2)}
.btn-detail{background:var(--dark);color:white;width:100%;justify-content:center;margin-top:auto;border-radius:var(--radius-sm)}
.btn-detail:hover{background:#1e2d40;transform:translateY(-1px);box-shadow:var(--shadow)}
.btn-green{background:var(--green);color:white}
.btn-green:hover{background:#047857;transform:translateY(-1px)}

/* ── Progress ── */
.progress-bar{background:var(--border);border-radius:20px;height:8px;overflow:hidden;margin:8px 0}
.progress-fill{height:100%;border-radius:20px;background:linear-gradient(90deg,var(--green),#34d399);transition:width .5s cubic-bezier(.4,0,.2,1)}

/* ── Tags ── */
.tag{display:inline-block;border-radius:20px;padding:4px 12px;font-size:13.5px;font-weight:700}
.tag-blue  {background:var(--blue-l);  color:var(--blue)}
.tag-green {background:var(--green-l); color:var(--green)}
.tag-orange{background:var(--orange-l);color:var(--orange)}
.tag-red   {background:var(--red-l);   color:var(--red)}

/* ── Alerts ── */
.alert-tip {background:var(--green-l);border:1.5px solid var(--green-m);border-radius:var(--radius-sm);padding:14px 18px;margin:12px 0;font-size:15.5px}
.alert-warn{background:var(--red-l);  border:1.5px solid var(--red-m);  border-radius:var(--radius-sm);padding:14px 18px;margin:12px 0;font-size:15.5px}

/* ── Nav & Divider ── */
.topic-nav{display:flex;gap:10px;margin:28px 0 0;flex-wrap:wrap}
.divider{border:none;border-top:1px solid var(--border);margin:24px 0}

/* ── Inline helpers ── */
.hl{background:#fef08a;padding:1px 5px;border-radius:4px;font-weight:700;color:var(--dark)}
.gr{color:var(--green); font-weight:700}
.bl{color:var(--blue);  font-weight:700}
.or{color:var(--orange);font-weight:700}
.rd{color:var(--red);   font-weight:700}
.pu{color:var(--purple);font-weight:700}

/* ── Footer ── */
footer{background:var(--header);color:rgba(255,255,255,.4);text-align:center;padding:22px;font-size:14px;margin-top:48px}

/* ── Fraction ── */
.fraction{display:inline-flex;flex-direction:column;align-items:center;margin:0 6px;vertical-align:middle}
.fraction .num{border-bottom:2px solid currentColor;padding:0 4px 2px;font-weight:700}
.fraction .den{padding:2px 4px 0;font-weight:700}