/* ─── MATEMATIKA 11 — Švarus minimalistinis stilius ─────────────────────── */

@import url('https://fonts.googleapis.com/css2?family=Geist:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --bg:         #f7f6f2;
  --bg2:        #ffffff;
  --bg3:        #efede8;

  --ink:        #141414;
  --ink2:       #555550;
  --ink3:       #999890;

  --border:     #e5e3dc;

  --accent:     #141414;
  --accent-bg:  #f0efeb;
  --accent-lt:  #e0dfd9;

  --green:      #1a7a4a;
  --green-bg:   #edf7f2;
  --green-lt:   #c6ebd8;

  --amber:      #92600a;
  --amber-bg:   #fdf5e6;
  --amber-lt:   #f5dda8;

  --red:        #b91c1c;
  --red-bg:     #fef2f2;
  --red-lt:     #fecaca;

  --purple:     #5b21b6;
  --purple-bg:  #f3f0fc;
  --purple-lt:  #ddd5f8;

  --radius-sm:  6px;
  --radius:     10px;
  --radius-lg:  14px;

  --sans: 'Geist', system-ui, sans-serif;
  --mono: 'JetBrains Mono', monospace;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow:    0 2px 8px rgba(0,0,0,0.07), 0 1px 3px rgba(0,0,0,0.04);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--ink);
  font-size: 15px;
  line-height: 1.65;
  min-height: 100vh;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 24px 24px;
  background-attachment: fixed;
}

/* ─── LAYOUT ─────────────────────────────────────────────────────────────── */
.layout { display: flex; min-height: 100vh; }

/* ─── SIDEBAR ────────────────────────────────────────────────────────────── */
.sidebar {
  width: 272px;
  flex-shrink: 0;
  background: var(--bg2);
  border-right: 1px solid var(--border);
  position: fixed;
  top: 0; left: 0;
  height: 100vh;
  overflow-y: auto;
  z-index: 100;
  display: flex;
  flex-direction: column;
}

.sidebar-logo {
  padding: 18px 16px 14px;
  border-bottom: 1px solid var(--border);
}

.sidebar-logo .brand {
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: -0.4px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.sidebar-logo .brand::before {
  content: '';
  width: 22px;
  height: 22px;
  background: var(--ink);
  border-radius: 6px;
  flex-shrink: 0;
  display: inline-block;
}

.sidebar-logo .brand span { color: var(--ink3); font-weight: 400; }

.sidebar-logo .sub {
  font-size: 10.5px;
  color: var(--ink3);
  margin-top: 3px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding-left: 30px;
}

.sidebar-section { padding: 14px 10px 6px; }

.sidebar-section-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink3);
  padding: 0 8px;
  margin-bottom: 4px;
}

.subject { margin-bottom: 1px; border-radius: var(--radius); overflow: hidden; }

.subject-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 8px;
  cursor: pointer;
  border-radius: var(--radius);
  transition: background 0.1s;
  user-select: none;
}

.subject-header:hover { background: var(--bg3); }
.subject-header.active { background: var(--ink); }
.subject-header.active .subject-name { color: #fff; font-weight: 500; }
.subject-header.active .subject-chevron { color: rgba(255,255,255,0.4); }

.subject-num { font-size: 11px; color: var(--ink3); width: 16px; flex-shrink: 0; font-weight: 500; }
.subject-name { font-size: 13px; color: var(--ink2); flex: 1; line-height: 1.3; }
.subject-chevron { font-size: 9px; color: var(--ink3); transition: transform 0.18s; flex-shrink: 0; }
.subject-chevron.open { transform: rotate(90deg); }

.topic-list { display: none; padding: 2px 0 5px 24px; }
.topic-list.open { display: block; }

.topic-link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 5px 8px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--ink2);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.1s, color 0.1s;
  line-height: 1.35;
}

.topic-link:hover { background: var(--bg3); color: var(--ink); }
.topic-link.active { background: var(--accent-bg); color: var(--ink); font-weight: 500; }

.topic-dot { width: 4px; height: 4px; border-radius: 50%; background: var(--border); flex-shrink: 0; }
.topic-link.active .topic-dot { background: var(--ink); }
.topic-link.done .topic-dot   { background: var(--green); }

.sidebar-divider { height: 1px; background: var(--border); margin: 6px 10px; }

.sidebar-bottom { margin-top: auto; border-top: 1px solid var(--border); padding: 10px; }

.sidebar-action {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 8px;
  border-radius: var(--radius);
  font-size: 12.5px;
  color: var(--ink2);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.1s;
}
.sidebar-action:hover { background: var(--bg3); color: var(--ink); }
.sidebar-action.exam  { color: var(--amber); font-weight: 500; }

/* ─── MAIN ───────────────────────────────────────────────────────────────── */
.main { margin-left: 272px; flex: 1; display: flex; flex-direction: column; min-height: 100vh; }

/* ─── TOPBAR ─────────────────────────────────────────────────────────────── */
.topbar {
  background: rgba(255,255,255,0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 36px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 50;
  gap: 16px;
}

.breadcrumb { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--ink3); flex-shrink: 0; }
.breadcrumb a { color: var(--ink3); text-decoration: none; transition: color 0.1s; }
.breadcrumb a:hover { color: var(--ink); }
.breadcrumb .sep { color: var(--border); }
.breadcrumb .current { color: var(--ink); font-weight: 500; }

.tab-switcher { display: flex; gap: 2px; background: var(--bg3); border-radius: 9px; padding: 3px; }

.tab-btn {
  padding: 5px 16px;
  border-radius: 7px;
  font-size: 13px;
  font-family: var(--sans);
  color: var(--ink3);
  cursor: pointer;
  border: none;
  background: transparent;
  transition: all 0.12s;
  font-weight: 400;
}
.tab-btn:hover { color: var(--ink); }
.tab-btn.active { background: var(--bg2); color: var(--ink); font-weight: 500; box-shadow: var(--shadow-sm); }

/* ─── PAGE ───────────────────────────────────────────────────────────────── */
.page { padding: 36px 44px 64px; max-width: 800px; width: 100%; }

/* ─── TOPIC HEADER ───────────────────────────────────────────────────────── */
.topic-header { margin-bottom: 30px; }

.topic-tag {
  display: inline-block;
  font-size: 10.5px;
  font-weight: 500;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink3);
  margin-bottom: 10px;
}

.topic-title {
  font-size: 28px;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.18;
  letter-spacing: -0.6px;
  margin-bottom: 8px;
}

.topic-intro { font-size: 14px; color: var(--ink2); max-width: 540px; line-height: 1.68; }

/* ─── THEORY BLOCKS ──────────────────────────────────────────────────────── */
.theory-block {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px 24px;
  margin-bottom: 12px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.15s, border-color 0.15s;
}
.theory-block:hover { box-shadow: var(--shadow); border-color: #d4d2cb; }

.block-title {
  font-size: 14.5px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.block-num {
  width: 26px; height: 26px;
  border-radius: 8px;
  background: var(--ink);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.def-row {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 10px 12px;
  background: var(--bg3);
  border-radius: var(--radius);
  margin-bottom: 10px;
}

.def-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink2);
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 2px 7px;
  flex-shrink: 0;
  margin-top: 1px;
}

.def-text { font-size: 13.5px; color: var(--ink2); line-height: 1.65; }

.formula {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 13px 18px;
  margin: 12px 0;
  font-family: var(--mono);
  font-size: 14px;
  color: var(--ink);
  text-align: center;
  letter-spacing: 0.02em;
  line-height: 1.8;
}

.note-box {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 10px 12px;
  background: var(--amber-bg);
  border: 1px solid var(--amber-lt);
  border-radius: var(--radius);
  margin: 10px 0;
}
.note-label { font-size: 10px; font-weight: 600; letter-spacing: 0.07em; text-transform: uppercase; color: var(--amber); flex-shrink: 0; margin-top: 2px; }
.note-text  { font-size: 13px; color: var(--amber); line-height: 1.6; }

.example-box {
  border-left: 2px solid var(--green);
  background: var(--green-bg);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 12px 14px;
  margin: 10px 0;
}
.example-label { font-size: 10px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--green); margin-bottom: 5px; }
.example-text  { font-size: 13.5px; color: var(--ink2); line-height: 1.65; }
.example-text strong { color: var(--ink); font-weight: 500; }

.math {
  font-family: var(--mono);
  font-size: 13px;
  background: var(--bg3);
  border: 1px solid var(--border);
  padding: 1px 6px;
  border-radius: 4px;
  color: var(--ink);
}

/* ─── TOPIC NAV ──────────────────────────────────────────────────────────── */
.topic-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 36px;
  padding-top: 22px;
  border-top: 1px solid var(--border);
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: var(--radius);
  font-size: 13px;
  font-family: var(--sans);
  font-weight: 500;
  cursor: pointer;
  border: 1px solid var(--border);
  background: var(--bg2);
  color: var(--ink2);
  text-decoration: none;
  transition: all 0.12s;
  box-shadow: var(--shadow-sm);
}
.btn:hover { border-color: var(--ink); color: var(--ink); box-shadow: var(--shadow); }

.btn.primary {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
  box-shadow: 0 2px 8px rgba(0,0,0,0.18);
}
.btn.primary:hover { background: #2a2a2a; box-shadow: 0 4px 14px rgba(0,0,0,0.24); transform: translateY(-1px); }

.btn.ghost { border-color: transparent; background: transparent; color: var(--ink3); box-shadow: none; }
.btn.ghost:hover { background: var(--bg3); color: var(--ink); border-color: transparent; }

.section-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink3);
  margin-bottom: 10px;
  margin-top: 28px;
}

.row-taisykle { background: var(--purple-bg); border-left: 2px solid var(--purple); }
.row-taisykle .row-label { color: var(--purple); background: var(--purple-bg); border-color: var(--purple-lt); }

@media (max-width: 720px) {
  .sidebar { display: none; }
  .main    { margin-left: 0; }
  .page    { padding: 22px 18px 48px; }
  .topbar  { padding: 0 18px; }
}