:root {
    --drk-red: #e30613;
    --drk-red-dark: #b8050f;
    --drk-red-light: #fce4e6;
    --drk-bg: #f0f2f5;
    --drk-card: #ffffff;
    --drk-text: #1a1a2e;
    --drk-muted: #6c757d;
    --drk-border: #dee2e6;
    --drk-success: #198754;
    --drk-warning: #ffc107;
    --drk-dark: #1a1a2e;
    --drk-dark-lighter: #252542;
    --drk-accent: #e30613;
    --shadow-sm: 0 1px 3px rgba(0,0,0,.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,.1);
    --shadow-lg: 0 8px 30px rgba(0,0,0,.12);
    --radius: 10px;
    --radius-lg: 16px;
}

* { box-sizing: border-box; }

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: var(--drk-bg);
    color: var(--drk-text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    margin: 0;
}

/* ─── Navbar ─── */
.navbar-drk {
    background: linear-gradient(135deg, var(--drk-dark) 0%, #16213e 100%);
    box-shadow: var(--shadow-md);
    padding: .6rem 0;
    position: sticky;
    top: 0;
    z-index: 1030;
}
.navbar-drk .navbar-brand {
    color: #fff !important;
    font-weight: 700;
    font-size: 1.15rem;
    display: flex;
    align-items: center;
    gap: .5rem;
}
.navbar-drk .navbar-brand .brand-cross {
    background: var(--drk-red);
    color: #fff;
    width: 32px;
    height: 32px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
}
.navbar-drk .nav-link {
    color: rgba(255,255,255,.78) !important;
    font-size: .9rem;
    padding: .5rem .85rem !important;
    border-radius: 6px;
    transition: all .2s;
}
.navbar-drk .nav-link:hover {
    color: #fff !important;
    background: rgba(255,255,255,.08);
}
.navbar-drk .nav-link.active {
    color: #fff !important;
    background: rgba(227,6,19,.35);
    font-weight: 600;
}
.navbar-drk .dropdown-menu {
    background: var(--drk-dark);
    border: 1px solid rgba(255,255,255,.1);
    border-radius: var(--radius);
    padding: .5rem;
}
.navbar-drk .dropdown-menu .dropdown-item {
    color: rgba(255,255,255,.8);
    border-radius: 6px;
    padding: .5rem .75rem;
    font-size: .9rem;
}
.navbar-drk .dropdown-menu .dropdown-item:hover {
    background: rgba(255,255,255,.1);
    color: #fff;
}
.navbar-drk .dropdown-menu .dropdown-divider {
    border-color: rgba(255,255,255,.1);
}
.navbar-drk .navbar-toggler {
    border-color: rgba(255,255,255,.25);
    padding: .25rem .5rem;
}
.navbar-drk .navbar-toggler-icon { filter: invert(1); }

.nav-badge {
    font-size: .65rem;
    padding: .15em .45em;
    vertical-align: top;
    margin-left: 2px;
}

/* ─── Buttons ─── */
.btn-drk {
    background: var(--drk-red);
    border-color: var(--drk-red);
    color: #fff;
    border-radius: var(--radius);
    font-weight: 500;
    transition: all .2s;
}
.btn-drk:hover, .btn-drk:focus {
    background: var(--drk-red-dark);
    border-color: var(--drk-red-dark);
    color: #fff;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(227,6,19,.3);
}
.btn-outline-drk {
    border-color: var(--drk-red);
    color: var(--drk-red);
    border-radius: var(--radius);
    font-weight: 500;
}
.btn-outline-drk:hover {
    background: var(--drk-red);
    color: #fff;
}

/* ─── Category Cards ─── */
.category-card {
    border: none;
    border-radius: var(--radius-lg);
    transition: transform .25s, box-shadow .25s;
    overflow: hidden;
    height: 100%;
    background: var(--drk-card);
}
.category-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
}
.category-card .card-body { padding: 1.5rem; }
.category-icon {
    width: 56px;
    height: 56px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    background: var(--drk-red-light);
    color: var(--drk-red);
    margin-bottom: 1rem;
}

/* ─── Hero ─── */
.hero-section {
    background: linear-gradient(135deg, var(--drk-dark) 0%, #16213e 60%, var(--drk-red-dark) 100%);
    color: #fff;
    padding: 3.5rem 0 3rem;
    margin-top: -2rem;
    margin-bottom: 2rem;
    position: relative;
    overflow: hidden;
}
.hero-section::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 60px;
    background: linear-gradient(to bottom, transparent, var(--drk-bg));
}
.hero-section h1 { font-weight: 800; font-size: 2.2rem; }
.hero-section .lead { opacity: .85; font-size: 1.1rem; }

/* ─── Section Cards (Home) ─── */
.section-card {
    background: var(--drk-card);
    border-radius: var(--radius-lg);
    padding: 1.8rem;
    height: 100%;
    transition: transform .2s, box-shadow .2s;
    border: 1px solid var(--drk-border);
    text-decoration: none;
    color: inherit;
    display: block;
}
.section-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    color: inherit;
    text-decoration: none;
}
.section-icon {
    width: 52px;
    height: 52px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    margin-bottom: 1rem;
}
.section-icon.red { background: var(--drk-red-light); color: var(--drk-red); }
.section-icon.blue { background: #e3f2fd; color: #1565c0; }
.section-icon.green { background: #e8f5e9; color: #2e7d32; }
.section-icon.purple { background: #f3e5f5; color: #7b1fa2; }
.section-icon.orange { background: #fff3e0; color: #e65100; }
.section-icon.dark { background: #e8eaf6; color: #283593; }

/* ─── Progress Bar ─── */
.progress-drk { height: 6px; border-radius: 3px; background: #eee; }
.progress-drk .progress-bar { background: var(--drk-red); border-radius: 3px; }

/* ─── Content Area ─── */
.content-area { flex: 1; padding: 2rem 0; }

/* ─── Stat Cards ─── */
.stat-card {
    background: var(--drk-card);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--drk-border);
}
.stat-card .stat-number { font-size: 1.8rem; font-weight: 700; color: var(--drk-red); }
.stat-card .stat-label { color: var(--drk-muted); font-size: .85rem; }

/* ─── Lesson Content ─── */
.lesson-content {
    background: var(--drk-card);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    line-height: 1.8;
}
.lesson-content img { max-width: 100%; border-radius: 8px; margin: 1rem 0; }

/* ─── Quiz ─── */
.quiz-option {
    border: 2px solid var(--drk-border);
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-bottom: .75rem;
    cursor: pointer;
    transition: border-color .2s, background .2s;
}
.quiz-option:hover { border-color: var(--drk-red); background: #fff5f5; }
.quiz-option.selected { border-color: var(--drk-red); background: var(--drk-red-light); }
.quiz-option.correct { border-color: var(--drk-success); background: #d1e7dd; }
.quiz-option.incorrect { border-color: #dc3545; background: #f8d7da; }

/* ─── Flashcards ─── */
.flashcard-container { perspective: 1000px; width: 100%; max-width: 500px; height: 300px; margin: 2rem auto; }
.flashcard { width: 100%; height: 100%; position: relative; transform-style: preserve-3d; transition: transform .6s; cursor: pointer; }
.flashcard.flipped { transform: rotateY(180deg); }
.flashcard-front, .flashcard-back {
    position: absolute; inset: 0; backface-visibility: hidden; border-radius: var(--radius-lg);
    display: flex; align-items: center; justify-content: center; padding: 2rem;
    text-align: center; font-size: 1.2rem; box-shadow: var(--shadow-md);
}
.flashcard-front { background: var(--drk-card); border: 2px solid var(--drk-border); }
.flashcard-back { background: var(--drk-red); color: #fff; transform: rotateY(180deg); }

/* ─── Auth Pages ─── */
.auth-card { max-width: 440px; margin: 3rem auto; }

/* ─── Footer ─── */
.footer-drk {
    background: var(--drk-dark);
    color: rgba(255,255,255,.6);
    padding: 2.5rem 0 1.5rem;
    margin-top: auto;
}
.footer-drk a { color: rgba(255,255,255,.8); text-decoration: none; transition: color .2s; }
.footer-drk a:hover { color: #fff; }
.footer-drk h6 { color: rgba(255,255,255,.9); font-weight: 600; margin-bottom: .75rem; }
.footer-links { list-style: none; padding: 0; margin: 0; }
.footer-links li { margin-bottom: .4rem; }
.footer-links a { font-size: .9rem; }

/* ─── Admin Sidebar ─── */
.admin-sidebar {
    background: var(--drk-dark);
    min-height: calc(100vh - 56px);
    padding-top: 1rem;
}
.admin-sidebar .nav-link {
    color: rgba(255,255,255,.7) !important;
    padding: .6rem 1rem;
    border-radius: 8px;
    margin: 2px 8px;
    font-size: .9rem;
}
.admin-sidebar .nav-link:hover,
.admin-sidebar .nav-link.active {
    color: #fff !important;
    background: rgba(255,255,255,.1);
}
.admin-sidebar .sidebar-section {
    font-size: .7rem;
    text-transform: uppercase;
    letter-spacing: .05em;
    color: rgba(255,255,255,.4);
    padding: .75rem 1rem .25rem;
    margin-top: .5rem;
}

/* ─── Breadcrumb ─── */
.breadcrumb-drk { background: transparent; padding: 0; margin-bottom: 1.5rem; }
.breadcrumb-drk .breadcrumb-item a { color: var(--drk-red); text-decoration: none; }

/* ─── Badges ─── */
.badge-leicht { background: #198754; }
.badge-mittel { background: #ffc107; color: #333; }
.badge-schwer { background: #dc3545; }
.role-badge-admin { background: var(--drk-red); }
.role-badge-editor { background: #0d6efd; }
.role-badge-user { background: #6c757d; }

/* ─── Online Indicator ─── */
.online-dot {
    display: inline-block;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #198754;
    margin-right: 4px;
    animation: pulse-green 2s infinite;
}
@keyframes pulse-green {
    0%, 100% { opacity: 1; }
    50% { opacity: .5; }
}

/* ─── Empty State ─── */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--drk-muted);
}
.empty-state i { font-size: 3rem; margin-bottom: 1rem; display: block; opacity: .4; }

/* ─── Activity Feed ─── */
.activity-item {
    padding: .75rem 0;
    border-bottom: 1px solid var(--drk-border);
    font-size: .9rem;
}
.activity-item:last-child { border-bottom: none; }

/* ─── Responsive ─── */
@media (max-width: 768px) {
    .hero-section { padding: 2rem 0 1.5rem; }
    .hero-section h1 { font-size: 1.6rem; }
    .category-icon { width: 44px; height: 44px; font-size: 1.1rem; }
    .flashcard-container { height: 250px; }
    .stat-card .stat-number { font-size: 1.4rem; }
    .section-card { padding: 1.2rem; }
}

/* ─── Blaulicht Easter Egg ─── */
.blaulicht-mode .navbar-drk {
    animation: blaulicht 1s infinite;
}
@keyframes blaulicht {
    0%, 100% { box-shadow: 0 0 20px rgba(0,100,255,.6); }
    50% { box-shadow: 0 0 20px rgba(227,6,19,.6); }
}