:root {
    --bg: #f4f6f9;
    --surface: #ffffff;
    --text: #1f2933;
    --muted: #647084;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --border: #e2e8f0;
    --error-bg: #fef2f2;  --error: #b91c1c;  --error-border: #fecaca;
    --success-bg: #f0fdf4; --success: #15803d; --success-border: #bbf7d0;
    --radius: 10px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Üst menü */
.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}
.logo {
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--primary);
    text-decoration: none;
}
.site-header nav {
    display: flex;
    align-items: center;
    gap: 18px;
}
.site-header nav a {
    color: var(--text);
    text-decoration: none;
    font-size: 0.95rem;
}
.site-header nav a:hover { color: var(--primary); }
.nav-user { color: var(--muted); font-size: 0.9rem; }

main.container {
    padding-top: 32px;
    padding-bottom: 48px;
}

/* Giriş / kayıt kartı */
.auth-card {
    max-width: 420px;
    margin: 24px auto;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
}
.auth-card h1 { margin-top: 0; font-size: 1.5rem; }
.auth-card label {
    display: block;
    margin-bottom: 14px;
    font-size: 0.9rem;
    color: var(--muted);
}
.auth-card input {
    display: block;
    width: 100%;
    margin-top: 6px;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    color: var(--text);
}
.auth-card input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}
.auth-alt { margin-top: 18px; font-size: 0.9rem; color: var(--muted); }
.auth-alt a { color: var(--primary); }

/* Buton */
.btn {
    display: inline-block;
    width: 100%;
    padding: 11px 16px;
    border: none;
    border-radius: 8px;
    background: var(--primary);
    color: #fff;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
}
.btn:hover { background: var(--primary-dark); }

/* Uyarı kutuları */
.alert {
    padding: 10px 14px;
    border-radius: 8px;
    margin-bottom: 16px;
    font-size: 0.9rem;
    border: 1px solid transparent;
}
.alert-error   { background: var(--error-bg);   color: var(--error);   border-color: var(--error-border); }
.alert-success { background: var(--success-bg); color: var(--success); border-color: var(--success-border); }

/* Alt bilgi */
.site-footer {
    border-top: 1px solid var(--border);
    color: var(--muted);
    font-size: 0.85rem;
    text-align: center;
    padding: 20px 0;
}

/* ============================================================
   2. AŞAMA — Ders listesi ve ders sayfası
   ============================================================ */

/* İlerleme çubuğu */
.progress-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 18px 20px;
    margin-bottom: 28px;
}
.progress-head {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    color: var(--muted);
    margin-bottom: 10px;
}
.progress-bar {
    height: 10px;
    background: #e9eef5;
    border-radius: 999px;
    overflow: hidden;
}
.progress-fill {
    height: 100%;
    background: var(--primary);
    border-radius: 999px;
    transition: width 0.3s ease;
}

/* Seviye bölümleri */
.level-section { margin-bottom: 30px; }
.level-title {
    font-size: 1.1rem;
    color: var(--muted);
    border-bottom: 1px solid var(--border);
    padding-bottom: 8px;
    margin-bottom: 16px;
}

/* Ders kartları */
.lesson-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 14px;
}
.lesson-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 18px;
    text-decoration: none;
    color: var(--text);
    transition: border-color 0.15s, box-shadow 0.15s;
}
.lesson-card:hover {
    border-color: var(--primary);
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.08);
}
.lesson-card.is-done { border-left: 4px solid var(--success); }
.lesson-card-title { font-weight: 600; }

.badge {
    font-size: 0.72rem;
    font-weight: 600;
    padding: 4px 9px;
    border-radius: 999px;
    white-space: nowrap;
}
.badge-done { background: var(--success-bg); color: var(--success); }
.badge-todo { background: #eef2ff; color: var(--primary); }

.admin-hint { color: var(--muted); font-size: 0.85rem; margin-top: 30px; }

/* ---- Ders sayfası ---- */
.breadcrumb { margin-bottom: 8px; }
.breadcrumb a { color: var(--primary); text-decoration: none; font-size: 0.9rem; }

.lesson {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 32px;
}
.lesson-header { margin-bottom: 20px; }
.lesson-level {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--primary);
    background: #eef2ff;
    padding: 3px 10px;
    border-radius: 999px;
    margin-bottom: 8px;
}
.lesson-header h1 { margin: 6px 0 0; }

/* Ders içeriği tipografisi */
.lesson-content { line-height: 1.75; }
.lesson-content h3 { margin-top: 24px; }
.lesson-content p { margin: 12px 0; }
.lesson-content ul { padding-left: 22px; }
.lesson-content li { margin: 6px 0; }
.lesson-content code {
    background: #f1f5f9;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: ui-monospace, "Cascadia Code", Consolas, monospace;
    font-size: 0.9em;
}
.lesson-content pre {
    background: #0f172a;
    color: #e2e8f0;
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    line-height: 1.5;
}
.lesson-content pre code {
    background: none;
    padding: 0;
    color: inherit;
}

/* Görevler */
.tasks {
    margin-top: 28px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}
.task-list { padding-left: 20px; }
.task-item { margin-bottom: 18px; }
.task-item h3 { margin: 0 0 4px; font-size: 1rem; }
.task-item p { margin: 0; color: #374151; }
.muted-note { color: var(--muted); font-size: 0.85rem; font-style: italic; }

/* Tamamlama butonu */
.complete-area { margin-top: 26px; }
.complete-btn { width: auto; padding: 11px 22px; }
.complete-btn.is-done { background: var(--success); }
.complete-btn.is-done:hover { background: #166534; }

/* Önceki / sonraki */
.lesson-nav {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    margin-top: 26px;
    padding-top: 18px;
    border-top: 1px solid var(--border);
}
.lesson-nav a {
    color: var(--primary);
    text-decoration: none;
    font-size: 0.9rem;
    max-width: 45%;
}
.lesson-nav a:hover { text-decoration: underline; }