:root {
  --bg: #0d1117;
  --bg2: #161b22;
  --bg3: #21262d;
  --border: #30363d;
  --text: #e6edf3;
  --muted: #8b949e;
  --blue: #388bfd;
  --green: #3fb950;
  --red: #f85149;
  --yellow: #d29922;
  --accent: #1f6feb;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { background: var(--bg); color: var(--text); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; font-size: 15px; line-height: 1.6; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
code { background: var(--bg3); padding: 2px 6px; border-radius: 4px; font-family: 'Courier New', monospace; font-size: 0.9em; }
pre { background: var(--bg3); padding: 12px; border-radius: 6px; overflow-x: auto; border: 1px solid var(--border); }
pre code { background: none; padding: 0; }

/* Nav */
.topnav { background: var(--bg2); border-bottom: 1px solid var(--border); display: flex; align-items: center; padding: 0 24px; height: 56px; gap: 16px; position: sticky; top: 0; z-index: 100; }
.brand { font-weight: 700; font-size: 1.1em; color: var(--text); }
.version { font-size: 0.75em; color: var(--muted); background: var(--bg3); padding: 2px 8px; border-radius: 10px; margin-left: 4px; }
.nav-links { margin-left: auto; display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.nav-links a { color: var(--muted); font-size: 0.9em; }
.nav-links a:hover { color: var(--text); }
.btn-nav { background: var(--accent); color: #fff !important; padding: 5px 14px; border-radius: 6px; font-size: 0.85em; }
.btn-nav:hover { background: var(--blue); }
.admin-link { color: var(--yellow) !important; }

/* Flash */
.flash { padding: 10px 24px; font-size: 0.9em; }
.flash.success { background: #1a3a2a; border-bottom: 1px solid var(--green); color: var(--green); }
.flash.error { background: #3a1a1a; border-bottom: 1px solid var(--red); color: var(--red); }

/* Main */
main { max-width: 1100px; margin: 0 auto; padding: 32px 24px; }
.site-footer { text-align: center; padding: 24px; color: var(--muted); font-size: 0.85em; border-top: 1px solid var(--border); margin-top: 40px; }

/* Buttons */
.btn-primary { background: var(--accent); color: #fff; border: none; padding: 8px 18px; border-radius: 6px; cursor: pointer; font-size: 0.9em; display: inline-block; }
.btn-primary:hover { background: var(--blue); text-decoration: none; }
.btn-secondary { background: var(--bg3); color: var(--text); border: 1px solid var(--border); padding: 8px 18px; border-radius: 6px; cursor: pointer; font-size: 0.9em; display: inline-block; }
.btn-secondary:hover { background: var(--bg2); text-decoration: none; }
.btn-sm { padding: 3px 10px; font-size: 0.8em; border-radius: 4px; background: var(--bg3); color: var(--text); border: 1px solid var(--border); cursor: pointer; display: inline-block; }
.btn-sm.danger { border-color: var(--red); color: var(--red); }

/* Forms */
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 0.85em; color: var(--muted); margin-bottom: 4px; }
input[type=text], input[type=email], input[type=password], textarea, select {
  width: 100%; background: var(--bg2); border: 1px solid var(--border); color: var(--text);
  padding: 8px 12px; border-radius: 6px; font-size: 0.9em; font-family: inherit;
}
input:focus, textarea:focus, select:focus { outline: none; border-color: var(--accent); }
.pw-wrap { position: relative; display: flex; }
.pw-wrap input { flex: 1; }
.pw-eye { background: var(--bg3); border: 1px solid var(--border); border-left: none; padding: 6px 10px; border-radius: 0 6px 6px 0; cursor: pointer; color: var(--muted); }
.form-row { display: flex; gap: 12px; margin-bottom: 12px; }
.form-row input, .form-row select { flex: 1; }

/* Auth box */
.auth-box { max-width: 400px; margin: 48px auto; background: var(--bg2); padding: 32px; border-radius: 10px; border: 1px solid var(--border); }
.auth-box h1 { margin-bottom: 24px; }
.auth-link { margin-top: 16px; font-size: 0.85em; color: var(--muted); }

/* Hero */
.hero { text-align: center; padding: 48px 0 32px; }
.hero h1 { font-size: 2em; margin-bottom: 10px; }
.hero .tagline { color: var(--muted); font-size: 1.1em; margin-bottom: 16px; }
.version-badge { background: var(--bg3); color: var(--blue); padding: 4px 12px; border-radius: 10px; font-size: 0.8em; display: inline-block; }

/* Language picker */
.lang-picker { margin: 32px 0; }
.lang-picker h2 { margin-bottom: 16px; color: var(--muted); font-size: 0.9em; text-transform: uppercase; letter-spacing: 1px; }
.lang-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.lang-card { background: var(--bg2); border: 2px solid var(--border); border-radius: 10px; padding: 24px; display: flex; flex-direction: column; align-items: center; gap: 8px; color: var(--text); transition: border-color 0.2s; }
.lang-card:hover { text-decoration: none; border-color: var(--blue); }
.lang-icon { font-size: 2em; }
.lang-name { font-weight: 600; }
.lang-action { color: var(--muted); font-size: 0.85em; }
.lang-cards.small { margin-top: 12px; }
.lang-card.small { padding: 12px 16px; flex-direction: row; gap: 8px; }

/* Features */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; margin: 32px 0; }
.feature-card { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 20px; }
.feature-card h3 { margin-bottom: 8px; }
.feature-card p { color: var(--muted); font-size: 0.9em; margin-bottom: 10px; }

/* Dictionary */
.dict-page { display: flex; gap: 24px; }
.dict-sidebar { width: 160px; flex-shrink: 0; }
.dict-sidebar h2 { font-size: 0.8em; text-transform: uppercase; color: var(--muted); margin-bottom: 10px; }
.lang-tab { display: block; padding: 8px 12px; border-radius: 6px; color: var(--muted); margin-bottom: 4px; }
.lang-tab:hover, .lang-tab.active { background: var(--bg2); color: var(--text); text-decoration: none; }
.dict-main { flex: 1; min-width: 0; }
.dict-header { margin-bottom: 20px; }
.dict-header p { color: var(--muted); }
.dict-search input { width: 100%; margin-bottom: 20px; }
.dict-entry { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 14px 16px; margin-bottom: 10px; }
.dict-symbol code { font-size: 1.1em; }
.dict-cat { font-size: 0.75em; background: var(--bg3); color: var(--muted); padding: 2px 8px; border-radius: 10px; margin-left: 8px; }
.dict-desc { color: var(--muted); font-size: 0.9em; margin-top: 6px; }
.dict-example { margin-top: 8px; }

/* Projects */
.projects-page .lang-tabs { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
.projects-header { margin-bottom: 24px; }
.projects-header p { color: var(--muted); }
.project-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }
.project-card { background: var(--bg2); border: 1px solid var(--border); border-radius: 10px; padding: 20px; display: flex; flex-direction: column; gap: 10px; }
.project-card.diff-beginner { border-left: 3px solid var(--green); }
.project-card.diff-intermediate { border-left: 3px solid var(--yellow); }
.project-card.diff-advanced { border-left: 3px solid var(--red); }
.project-header { display: flex; justify-content: space-between; align-items: start; }
.project-header h2 { font-size: 1em; }
.difficulty { font-size: 0.75em; color: var(--muted); background: var(--bg3); padding: 2px 8px; border-radius: 10px; }
.project-desc { color: var(--muted); font-size: 0.85em; flex: 1; }
.project-meta { font-size: 0.8em; color: var(--muted); display: flex; gap: 12px; }
.prog-badge { color: var(--blue); }

/* Dashboard */
.dashboard h1 { margin-bottom: 24px; }
.dash-stats { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 32px; }
.stat-card { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 16px 24px; display: flex; flex-direction: column; gap: 4px; }
.stat-icon { font-size: 1.5em; }
.stat-lang { font-size: 0.85em; color: var(--muted); }
.stat-num { font-size: 0.85em; }
.dash-section { margin-bottom: 32px; }
.dash-section h2 { margin-bottom: 16px; border-bottom: 1px solid var(--border); padding-bottom: 8px; }
.progress-list { display: flex; flex-direction: column; gap: 12px; }
.progress-item { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 16px 20px; display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.progress-item.completed { opacity: 0.7; }
.prog-info { flex: 1; min-width: 150px; }
.prog-info h3 { font-size: 0.95em; margin-bottom: 2px; }
.prog-lang { font-size: 0.75em; color: var(--muted); }
.prog-diff { font-size: 0.75em; color: var(--muted); background: var(--bg3); padding: 1px 6px; border-radius: 8px; }
.prog-bar-wrap { height: 6px; background: var(--bg3); border-radius: 3px; width: 100px; }
.prog-bar { height: 100%; background: var(--blue); border-radius: 3px; transition: width 0.3s; }
.prog-pages { font-size: 0.8em; color: var(--muted); white-space: nowrap; }
.badge-complete { color: var(--green); font-size: 0.85em; }
.empty-state { padding: 32px; text-align: center; color: var(--muted); background: var(--bg2); border-radius: 8px; }

/* Lesson */
.lesson-page { max-width: 800px; }
.lesson-nav { display: flex; align-items: center; gap: 16px; margin-bottom: 20px; font-size: 0.85em; color: var(--muted); }
.lesson-nav a { color: var(--blue); }
.lesson-title { font-weight: 600; color: var(--text); }
.lesson-page-num { margin-left: auto; }
.lesson-page h1 { margin-bottom: 16px; }
.lesson-progress { height: 4px; background: var(--bg3); border-radius: 2px; margin-bottom: 24px; }
.lesson-progress .prog-bar { background: var(--blue); }
.code-lines { display: flex; flex-direction: column; gap: 8px; margin-bottom: 32px; }
.code-line { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.code-line.checked { border-color: var(--green); background: #0d2018; }
.line-header { display: flex; align-items: center; gap: 12px; padding: 12px 16px; }
.line-check input { display: none; }
.checkmark { font-size: 1.1em; cursor: pointer; }
.line-code { font-family: 'Courier New', monospace; font-size: 0.9em; flex: 1; white-space: pre-wrap; word-break: break-all; }
.line-explain { border-top: 1px solid var(--border); }
.explain-toggle { width: 100%; background: none; border: none; color: var(--muted); padding: 8px 16px; text-align: left; cursor: pointer; font-size: 0.85em; }
.explain-toggle:hover { color: var(--text); }
.explain-body { padding: 12px 16px; color: var(--muted); font-size: 0.9em; }
.commands-used { margin-top: 8px; }
.cmd-tag { margin-right: 6px; color: var(--blue); }
.line-dict { margin-top: 10px; }
.dict-btn { background: none; border: 1px solid var(--border); border-radius: 4px; color: var(--muted); padding: 4px 10px; font-size: 0.8em; cursor: pointer; }
.dict-btn:hover { border-color: var(--blue); color: var(--blue); }
.dict-btn:disabled { opacity: 0.5; cursor: default; }
.dict-panel { margin-top: 8px; }
.line-dict-results .dict-entry { margin-bottom: 8px; }
.dict-empty { color: var(--muted); font-size: 0.85em; font-style: italic; margin-top: 6px; }
.all-check-hint { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 20px; text-align: center; color: var(--muted); }
.test-passed-banner { background: #0d2018; border: 1px solid var(--green); border-radius: 8px; padding: 20px; display: flex; align-items: center; gap: 16px; color: var(--green); }
.test-area { background: var(--bg2); border: 1px solid var(--border); border-radius: 10px; padding: 24px; }
.test-area h2 { margin-bottom: 8px; }
.test-area > p { color: var(--muted); margin-bottom: 20px; }
.test-question { margin-bottom: 20px; padding-bottom: 20px; border-bottom: 1px solid var(--border); }
.q-text { margin-bottom: 10px; }
.q-option { display: block; padding: 8px 12px; margin-bottom: 6px; border: 1px solid var(--border); border-radius: 6px; cursor: pointer; }
.q-option:hover { border-color: var(--blue); background: var(--bg3); }
.q-option input { margin-right: 8px; }

/* Test result */
.test-result-page { max-width: 700px; }
.test-result-page h1 { margin-bottom: 16px; }
.score-banner { padding: 16px 24px; border-radius: 8px; margin-bottom: 24px; font-size: 1.1em; }
.score-banner.pass { background: #0d2018; color: var(--green); border: 1px solid var(--green); }
.score-banner.fail { background: #2d0d0d; color: var(--red); border: 1px solid var(--red); }
.result-list { margin-bottom: 24px; }
.result-item { padding: 14px 16px; border-radius: 8px; margin-bottom: 10px; background: var(--bg2); border: 1px solid var(--border); }
.result-item.correct { border-left: 3px solid var(--green); }
.result-item.wrong { border-left: 3px solid var(--red); }
.result-q { margin-bottom: 6px; font-weight: 600; }
.result-actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* Admin */
.admin-page { display: flex; gap: 24px; }
.admin-sidebar { width: 160px; flex-shrink: 0; }
.admin-sidebar h3 { font-size: 0.8em; text-transform: uppercase; color: var(--muted); margin-bottom: 10px; }
.admin-sidebar a { display: block; padding: 8px 12px; border-radius: 6px; color: var(--muted); margin-bottom: 4px; }
.admin-sidebar a:hover, .admin-sidebar a.active { background: var(--bg2); color: var(--text); text-decoration: none; }
.admin-main { flex: 1; min-width: 0; }
.admin-main h1 { margin-bottom: 20px; display: flex; align-items: center; gap: 12px; }
.admin-stats { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 32px; }
.admin-stat { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 16px 24px; text-align: center; }
.admin-stat .stat-num { font-size: 2em; font-weight: 700; color: var(--blue); }
.admin-stat .stat-label { font-size: 0.8em; color: var(--muted); }
.admin-links { display: flex; gap: 16px; flex-wrap: wrap; margin-top: 16px; }
.admin-card { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 20px 24px; color: var(--text); }
.admin-card:hover { border-color: var(--blue); text-decoration: none; }
.admin-table { width: 100%; border-collapse: collapse; margin-top: 20px; }
.admin-table th { text-align: left; padding: 8px 12px; border-bottom: 2px solid var(--border); font-size: 0.8em; color: var(--muted); text-transform: uppercase; }
.admin-table td { padding: 10px 12px; border-bottom: 1px solid var(--border); font-size: 0.9em; }
.admin-table tr:hover td { background: var(--bg2); }
.disabled-row td { opacity: 0.5; }
.add-form { background: var(--bg2); border: 1px solid var(--border); border-radius: 8px; padding: 20px; margin-bottom: 24px; }
.add-form h3 { margin-bottom: 14px; }
.edit-form { max-width: 500px; }
.edit-form .form-group { margin-bottom: 16px; }