/* =========================================================================
   Учебная платформа — дизайн-система
   Токены → база → компоненты → утилиты → адаптив
   ========================================================================= */

/* -------------------------------------------------------------------------
   1. Токены
   ------------------------------------------------------------------------- */
:root {
    /* Палитра бренда */
    --brand-50:  #eef2ff;
    --brand-100: #e0e7ff;
    --brand-200: #c7d2fe;
    --brand-300: #a5b4fc;
    --brand-400: #818cf8;
    --brand-500: #6366f1;
    --brand-600: #4f46e5;
    --brand-700: #4338ca;
    --brand-800: #3730a3;

    /* Акцент для градиентов и подсветки */
    --accent-400: #22d3ee;
    --accent-500: #06b6d4;

    /* Поверхности и текст (светлая тема) */
    --bg:            #f6f7fb;
    --bg-pattern:    radial-gradient(1200px 600px at 12% -8%, #e8ecff 0%, transparent 60%),
                     radial-gradient(1000px 500px at 100% 0%, #e6fbff 0%, transparent 55%);
    --surface:       #ffffff;
    --surface-2:     #f4f6fa;
    --surface-3:     #eceff6;
    --surface-hover: #f8f9fd;
    --border:        #e5e8f0;
    --border-strong: #d3d8e4;

    --text:        #0f172a;
    --text-2:      #334155;
    --muted:       #64748b;
    --muted-soft:  #94a3b8;

    /* Семантика */
    --accent:      var(--brand-600);
    --accent-dark: var(--brand-700);
    --accent-soft: var(--brand-50);
    --success:      #047857;
    --success-soft: #ecfdf5;
    --success-line: #a7f3d0;
    --danger:       #be123c;
    --danger-soft:  #fff1f2;
    --danger-line:  #fecdd3;
    --warning:      #b45309;
    --warning-soft: #fffbeb;
    --warning-line: #fde68a;
    --info:         var(--brand-700);
    --info-soft:    var(--brand-50);
    --info-line:    var(--brand-200);

    /* Форма */
    --radius-xs: 6px;
    --radius-sm: 8px;
    --radius:    12px;
    --radius-lg: 16px;
    --radius-xl: 22px;
    --radius-pill: 999px;

    /* Тени */
    --shadow-xs: 0 1px 2px rgba(15, 23, 42, .05);
    --shadow-sm: 0 1px 2px rgba(15, 23, 42, .04), 0 2px 6px rgba(15, 23, 42, .04);
    --shadow-md: 0 2px 4px rgba(15, 23, 42, .04), 0 8px 24px rgba(15, 23, 42, .07);
    --shadow-lg: 0 4px 8px rgba(15, 23, 42, .05), 0 20px 48px rgba(15, 23, 42, .12);
    --ring: 0 0 0 4px rgba(99, 102, 241, .18);

    /* Прочее */
    --header-h: 64px;
    --ease: cubic-bezier(.22, 1, .36, 1);
    --sans: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
            "Helvetica Neue", "Noto Sans", Arial, sans-serif;
    --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

/* Тёмная тема: следует за системой, но переключатель имеет приоритет */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        color-scheme: dark;
        --bg:            #0a0c12;
        --bg-pattern:    radial-gradient(1200px 600px at 12% -8%, #1a1f3d 0%, transparent 60%),
                         radial-gradient(1000px 500px at 100% 0%, #0d2b33 0%, transparent 55%);
        --surface:       #12151d;
        --surface-2:     #191d27;
        --surface-3:     #212632;
        --surface-hover: #1a1e29;
        --border:        #262b38;
        --border-strong: #333a4a;

        --text:       #e8ecf5;
        --text-2:     #c3cad8;
        --muted:      #8f9bb3;
        --muted-soft: #6b7689;

        --accent:      var(--brand-400);
        --accent-dark: var(--brand-300);
        --accent-soft: #1e2140;
        --success:      #34d399;
        --success-soft: #0d2a22;
        --success-line: #1c5c48;
        --danger:       #fb7185;
        --danger-soft:  #2c1119;
        --danger-line:  #6b2233;
        --warning:      #fbbf24;
        --warning-soft: #2a1f08;
        --warning-line: #6b4d13;
        --info:         var(--brand-300);
        --info-soft:    #1a1d38;
        --info-line:    #343a6b;

        --shadow-xs: 0 1px 2px rgba(0, 0, 0, .4);
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, .4), 0 2px 6px rgba(0, 0, 0, .3);
        --shadow-md: 0 2px 4px rgba(0, 0, 0, .35), 0 8px 24px rgba(0, 0, 0, .45);
        --shadow-lg: 0 4px 8px rgba(0, 0, 0, .4), 0 20px 48px rgba(0, 0, 0, .6);
        --ring: 0 0 0 4px rgba(129, 140, 248, .25);
    }
}

:root[data-theme="dark"] {
    color-scheme: dark;
    --bg:            #0a0c12;
    --bg-pattern:    radial-gradient(1200px 600px at 12% -8%, #1a1f3d 0%, transparent 60%),
                     radial-gradient(1000px 500px at 100% 0%, #0d2b33 0%, transparent 55%);
    --surface:       #12151d;
    --surface-2:     #191d27;
    --surface-3:     #212632;
    --surface-hover: #1a1e29;
    --border:        #262b38;
    --border-strong: #333a4a;

    --text:       #e8ecf5;
    --text-2:     #c3cad8;
    --muted:      #8f9bb3;
    --muted-soft: #6b7689;

    --accent:      var(--brand-400);
    --accent-dark: var(--brand-300);
    --accent-soft: #1e2140;
    --success:      #34d399;
    --success-soft: #0d2a22;
    --success-line: #1c5c48;
    --danger:       #fb7185;
    --danger-soft:  #2c1119;
    --danger-line:  #6b2233;
    --warning:      #fbbf24;
    --warning-soft: #2a1f08;
    --warning-line: #6b4d13;
    --info:         var(--brand-300);
    --info-soft:    #1a1d38;
    --info-line:    #343a6b;

    --shadow-xs: 0 1px 2px rgba(0, 0, 0, .4);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, .4), 0 2px 6px rgba(0, 0, 0, .3);
    --shadow-md: 0 2px 4px rgba(0, 0, 0, .35), 0 8px 24px rgba(0, 0, 0, .45);
    --shadow-lg: 0 4px 8px rgba(0, 0, 0, .4), 0 20px 48px rgba(0, 0, 0, .6);
    --ring: 0 0 0 4px rgba(129, 140, 248, .25);
}

/* -------------------------------------------------------------------------
   2. База
   ------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    font-family: var(--sans);
    font-size: 15px;
    line-height: 1.6;
    color: var(--text);
    background-color: var(--bg);
    background-image: var(--bg-pattern);
    background-attachment: fixed;
    background-repeat: no-repeat;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    font-feature-settings: "cv02", "cv03", "cv04", "cv11";
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color .15s var(--ease);
}
a:hover { color: var(--accent-dark); text-decoration: none; }

/* Заголовки-ссылки наследуют цвет и подчёркиваются акцентом при наведении */
a.plain { color: inherit; }
a.plain:hover { color: var(--accent); }

img, svg { max-width: 100%; }

::selection { background: var(--brand-200); color: var(--brand-800); }

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
    border-radius: var(--radius-xs);
}

.container {
    width: 100%;
    max-width: 1180px;
    margin: 0 auto;
    padding: 0 24px;
}
.container-narrow { max-width: 820px; }

main {
    flex: 1;
    padding: 32px 0 72px;
    animation: page-in .35s var(--ease) both;
}

@keyframes page-in {
    from { opacity: 0; transform: translateY(6px); }
    to   { opacity: 1; transform: none; }
}

/* -------------------------------------------------------------------------
   3. Типографика
   ------------------------------------------------------------------------- */
h1, h2, h3, h4 {
    margin: 0;
    font-weight: 680;
    letter-spacing: -.02em;
    line-height: 1.25;
    color: var(--text);
}
h1 { font-size: clamp(26px, 3.2vw, 34px); letter-spacing: -.03em; }
h2 { font-size: 21px; margin: 40px 0 16px; }
h3 { font-size: 16px; margin: 0 0 10px; letter-spacing: -.015em; }
h4 { font-size: 14px; }

p { margin: 0 0 12px; }
p:last-child { margin-bottom: 0; }

strong, b { font-weight: 650; }

small { font-size: 13px; }

.muted { color: var(--muted); font-size: 14px; }
.lead {
    color: var(--muted);
    font-size: 17px;
    line-height: 1.6;
    margin: 8px 0 0;
    max-width: 62ch;
}
.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    font-size: 12px;
    font-weight: 650;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--accent);
}

/* Заголовок раздела с тонкой линией-акцентом */
.section-title {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    flex-wrap: wrap;
    margin: 40px 0 16px;
}
.section-title h2 { margin: 0; }
.section-title .muted { margin: 0; }

/* -------------------------------------------------------------------------
   4. Шапка
   ------------------------------------------------------------------------- */
.topbar {
    position: sticky;
    top: 0;
    z-index: 50;
    background: color-mix(in srgb, var(--surface) 82%, transparent);
    backdrop-filter: saturate(180%) blur(14px);
    -webkit-backdrop-filter: saturate(180%) blur(14px);
    border-bottom: 1px solid var(--border);
}
.topbar .container {
    display: flex;
    align-items: center;
    gap: 10px;
    min-height: var(--header-h);
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 16px;
    letter-spacing: -.02em;
    color: var(--text);
    white-space: nowrap;
    flex-shrink: 0;
}
.brand:hover { color: var(--text); }
.brand-mark {
    display: grid;
    place-items: center;
    width: 32px;
    height: 32px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--brand-500), var(--brand-700) 60%, var(--accent-500));
    color: #fff;
    box-shadow: 0 2px 8px rgba(79, 70, 229, .35);
    flex-shrink: 0;
}
.brand-mark svg { width: 18px; height: 18px; }

.nav {
    display: flex;
    align-items: center;
    gap: 2px;
    margin-left: 12px;
    min-width: 0;
}
.nav a {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    padding: 7px 12px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 520;
    color: var(--muted);
    white-space: nowrap;
    transition: background .15s var(--ease), color .15s var(--ease);
}
.nav a:hover { background: var(--surface-2); color: var(--text); }
.nav a.is-active { background: var(--accent-soft); color: var(--accent-dark); font-weight: 600; }
.nav a svg { width: 16px; height: 16px; opacity: .85; flex-shrink: 0; }

.nav-right {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

/* Круглая иконочная кнопка (тема, уведомления, бургер) */
.icon-btn {
    position: relative;
    display: grid;
    place-items: center;
    width: 36px;
    height: 36px;
    padding: 0;
    border: 1px solid transparent;
    border-radius: 10px;
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    transition: background .15s var(--ease), color .15s var(--ease), border-color .15s var(--ease);
}
.icon-btn:hover { background: var(--surface-2); color: var(--text); border-color: var(--border); }
.icon-btn svg { width: 18px; height: 18px; }

.badge-count {
    position: absolute;
    top: 2px;
    right: 2px;
    min-width: 17px;
    height: 17px;
    padding: 0 4px;
    border-radius: var(--radius-pill);
    background: linear-gradient(135deg, #f43f5e, #be123c);
    border: 2px solid var(--surface);
    color: #fff;
    font-size: 10px;
    font-weight: 700;
    line-height: 13px;
    text-align: center;
    box-shadow: 0 1px 4px rgba(190, 18, 60, .45);
}

/* Меню пользователя */
.usermenu { position: relative; }
.usermenu-trigger {
    display: inline-flex;
    align-items: center;
    gap: 9px;
    padding: 4px 10px 4px 4px;
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    background: var(--surface);
    color: var(--text);
    font: inherit;
    font-size: 14px;
    font-weight: 550;
    cursor: pointer;
    max-width: 220px;
    transition: background .15s var(--ease), border-color .15s var(--ease), box-shadow .15s var(--ease);
}
.usermenu-trigger:hover { background: var(--surface-2); border-color: var(--border-strong); }
.usermenu-trigger[aria-expanded="true"] { box-shadow: var(--ring); border-color: var(--accent); }
.usermenu-name {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.usermenu-trigger .chev { width: 14px; height: 14px; color: var(--muted); flex-shrink: 0; }

.avatar {
    display: grid;
    place-items: center;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--brand-400), var(--brand-700));
    color: #fff;
    font-size: 11.5px;
    font-weight: 700;
    letter-spacing: .02em;
    flex-shrink: 0;
    text-transform: uppercase;
}
.avatar-lg { width: 56px; height: 56px; font-size: 20px; border-radius: 18px; }

.menu {
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    z-index: 60;
    min-width: 240px;
    padding: 6px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px) scale(.98);
    transform-origin: top right;
    transition: opacity .16s var(--ease), transform .16s var(--ease), visibility .16s;
}
.menu.is-open { opacity: 1; visibility: visible; transform: none; }
.menu-head { padding: 10px 12px 12px; border-bottom: 1px solid var(--border); margin-bottom: 6px; }
.menu-head strong { display: block; font-size: 14px; }
.menu-head span { display: block; font-size: 12.5px; color: var(--muted); word-break: break-all; }
.menu a, .menu button {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    padding: 9px 12px;
    border: 0;
    border-radius: var(--radius-sm);
    background: none;
    color: var(--text-2);
    font: inherit;
    font-size: 14px;
    text-align: left;
    cursor: pointer;
    transition: background .12s var(--ease), color .12s var(--ease);
}
.menu a:hover, .menu button:hover { background: var(--surface-2); color: var(--text); }
.menu svg { width: 16px; height: 16px; color: var(--muted); flex-shrink: 0; }
.menu form { margin: 0; }
.menu hr { height: 1px; margin: 6px 0; border: 0; background: var(--border); }

/* Бургер и мобильная навигация */
.nav-toggle { display: none; }

/* -------------------------------------------------------------------------
   5. Шапка страницы и хлебные крошки
   ------------------------------------------------------------------------- */
.breadcrumbs {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 14px;
    font-size: 13.5px;
    color: var(--muted);
}
.breadcrumbs a { color: var(--muted); font-weight: 500; }
.breadcrumbs a:hover { color: var(--accent); }
.breadcrumbs .sep { color: var(--muted-soft); }
.breadcrumbs svg { width: 14px; height: 14px; }

.page-head {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 28px;
}
.page-head-main { min-width: 0; flex: 1 1 380px; }
.page-head .actions { flex-shrink: 0; }

/* Строка мета-данных под заголовком: «Преподаватель · 12 студентов · 8 уроков» */
.meta-row {
    display: flex;
    align-items: center;
    gap: 8px 14px;
    flex-wrap: wrap;
    margin-top: 10px;
    font-size: 14px;
    color: var(--muted);
}
.meta-row > span { display: inline-flex; align-items: center; gap: 6px; }
.meta-row svg { width: 15px; height: 15px; opacity: .75; }
.meta-row .dot { color: var(--muted-soft); }

/* -------------------------------------------------------------------------
   6. Карточки и сетки
   ------------------------------------------------------------------------- */
.card {
    position: relative;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 22px 24px;
    margin-bottom: 18px;
    box-shadow: var(--shadow-sm);
}
.card > h3:first-child { margin-top: 0; }
.card-pad-sm { padding: 16px 18px; }
.card-flush { padding: 0; overflow: hidden; }

.card-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    flex-wrap: wrap;
    margin-bottom: 14px;
}
.card-head h3 { margin: 0; }
.card-head:last-child { margin-bottom: 0; }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
    gap: 18px;
}
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }

/* Карточка курса: цветной корешок + подъём при наведении */
.course-card {
    display: flex;
    flex-direction: column;
    margin-bottom: 0;
    padding: 0;
    overflow: hidden;
    transition: transform .2s var(--ease), box-shadow .2s var(--ease), border-color .2s var(--ease);
}
.course-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    border-color: var(--border-strong);
}
.course-cover {
    position: relative;
    height: 84px;
    background: linear-gradient(120deg, var(--brand-500), var(--brand-700) 55%, var(--accent-500));
    overflow: hidden;
}
/* Разные курсы получают разные оттенки обложки */
.course-card:nth-child(4n+2) .course-cover { background: linear-gradient(120deg, #0ea5e9, #4f46e5 70%); }
.course-card:nth-child(4n+3) .course-cover { background: linear-gradient(120deg, #8b5cf6, #d946ef 75%); }
.course-card:nth-child(4n+4) .course-cover { background: linear-gradient(120deg, #14b8a6, #0f766e 70%); }
.course-cover::after {
    content: "";
    position: absolute;
    inset: 0;
    background:
        radial-gradient(400px 120px at 15% 120%, rgba(255, 255, 255, .35), transparent 70%),
        linear-gradient(transparent 40%, rgba(0, 0, 0, .12));
}
.course-cover .tag { position: absolute; top: 12px; right: 12px; z-index: 1; }
.course-body { padding: 18px 20px 20px; display: flex; flex-direction: column; flex: 1; gap: 10px; }
.course-body h3 { margin: 0; font-size: 16.5px; }
.course-desc {
    color: var(--muted);
    font-size: 14px;
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.course-foot {
    margin-top: auto;
    padding-top: 14px;
    border-top: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}
.course-tutor {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--muted);
    min-width: 0;
}
.course-tutor .avatar { width: 24px; height: 24px; font-size: 10px; }
.course-tutor span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* -------------------------------------------------------------------------
   7. Плитки статистики
   ------------------------------------------------------------------------- */
.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 14px;
    margin-bottom: 28px;
}
.stat {
    position: relative;
    padding: 18px 20px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    box-shadow: var(--shadow-xs);
    overflow: hidden;
}
.stat::before {
    content: "";
    position: absolute;
    left: 0; top: 0; bottom: 0;
    width: 3px;
    background: linear-gradient(var(--brand-400), var(--brand-600));
}
.stat-success::before { background: linear-gradient(#34d399, #059669); }
.stat-warning::before { background: linear-gradient(#fbbf24, #d97706); }
.stat-info::before    { background: linear-gradient(#22d3ee, #0891b2); }
.stat-label {
    display: flex;
    align-items: center;
    gap: 7px;
    font-size: 12.5px;
    font-weight: 600;
    letter-spacing: .03em;
    text-transform: uppercase;
    color: var(--muted);
}
.stat-label svg { width: 15px; height: 15px; }
.stat-value {
    margin-top: 6px;
    font-size: 28px;
    font-weight: 700;
    letter-spacing: -.03em;
    line-height: 1.1;
    color: var(--text);
    font-variant-numeric: tabular-nums;
}
.stat-value small { font-size: 15px; font-weight: 500; color: var(--muted); letter-spacing: 0; }
.stat-hint { margin-top: 4px; font-size: 13px; color: var(--muted); }

/* -------------------------------------------------------------------------
   8. Кнопки
   ------------------------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 9px 17px;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    background: linear-gradient(180deg, var(--brand-500), var(--brand-600));
    color: #fff;
    font: inherit;
    font-size: 14px;
    font-weight: 580;
    line-height: 1.4;
    white-space: nowrap;
    cursor: pointer;
    text-decoration: none;
    box-shadow: 0 1px 2px rgba(15, 23, 42, .12), inset 0 1px 0 rgba(255, 255, 255, .16);
    transition: transform .12s var(--ease), box-shadow .15s var(--ease),
                background .15s var(--ease), border-color .15s var(--ease), color .15s var(--ease);
}
.btn:hover {
    background: linear-gradient(180deg, var(--brand-600), var(--brand-700));
    color: #fff;
    box-shadow: 0 2px 6px rgba(79, 70, 229, .35), inset 0 1px 0 rgba(255, 255, 255, .16);
    transform: translateY(-1px);
}
.btn:active { transform: translateY(0); box-shadow: var(--shadow-xs); }
.btn svg { width: 16px; height: 16px; flex-shrink: 0; }

.btn-secondary {
    background: var(--surface);
    color: var(--text-2);
    border-color: var(--border-strong);
    box-shadow: var(--shadow-xs);
}
.btn-secondary:hover {
    background: var(--surface-2);
    color: var(--text);
    border-color: var(--muted-soft);
    box-shadow: var(--shadow-sm);
}

.btn-ghost {
    background: transparent;
    color: var(--muted);
    border-color: transparent;
    box-shadow: none;
}
.btn-ghost:hover { background: var(--surface-2); color: var(--text); box-shadow: none; }

.btn-danger {
    background: linear-gradient(180deg, #f43f5e, #be123c);
    border-color: transparent;
    color: #fff;
}
.btn-danger:hover {
    background: linear-gradient(180deg, #be123c, #9f1239);
    box-shadow: 0 2px 6px rgba(190, 18, 60, .35);
    color: #fff;
}

/* Тихая опасная кнопка — для «Удалить» в длинных списках */
.btn-danger-soft {
    background: var(--danger-soft);
    color: var(--danger);
    border-color: var(--danger-line);
    box-shadow: none;
}
.btn-danger-soft:hover {
    background: var(--danger);
    color: #fff;
    border-color: transparent;
}

.btn-success { background: linear-gradient(180deg, #10b981, #047857); }
.btn-success:hover { background: linear-gradient(180deg, #047857, #065f46); color: #fff; }

.btn-sm { padding: 5px 11px; font-size: 13px; border-radius: var(--radius-xs); gap: 6px; }
.btn-sm svg { width: 14px; height: 14px; }
.btn-lg { padding: 12px 24px; font-size: 15.5px; border-radius: var(--radius); }
.btn-lg svg { width: 18px; height: 18px; }
.btn-block { width: 100%; }

.btn:disabled, .btn[disabled] {
    opacity: .5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Квадратная кнопка-иконка внутри списков (стрелки вверх/вниз) */
.btn-icon { padding: 5px; width: 28px; height: 28px; }
.btn-icon svg { width: 14px; height: 14px; }

.actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.actions-end { justify-content: flex-end; }
.actions-between { justify-content: space-between; }
form.inline { display: inline-flex; margin: 0; }

/* -------------------------------------------------------------------------
   9. Формы
   ------------------------------------------------------------------------- */
.field { margin-bottom: 18px; }
.field:last-child { margin-bottom: 0; }
.field-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 0 18px;
}

label {
    display: block;
    font-size: 13.5px;
    font-weight: 600;
    color: var(--text-2);
    margin-bottom: 6px;
    letter-spacing: -.005em;
}
.field-hint { font-size: 13px; color: var(--muted); margin: 6px 0 0; }

input[type=text], input[type=email], input[type=password], input[type=number],
input[type=datetime-local], input[type=date], input[type=search], input[type=url],
select, textarea {
    width: 100%;
    padding: 10px 13px;
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-sm);
    font: inherit;
    font-size: 14.5px;
    background: var(--surface);
    color: var(--text);
    transition: border-color .15s var(--ease), box-shadow .15s var(--ease), background .15s var(--ease);
    appearance: none;
}
input::placeholder, textarea::placeholder { color: var(--muted-soft); }

select {
    padding-right: 38px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 15px;
    cursor: pointer;
}
:root[data-theme="dark"] select {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%238f9bb3' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) select {
        background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%238f9bb3' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
    }
}

textarea { min-height: 150px; resize: vertical; line-height: 1.65; }

input:hover:not(:disabled), select:hover:not(:disabled), textarea:hover:not(:disabled) {
    border-color: var(--muted-soft);
}
input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: var(--ring);
}
input:disabled, select:disabled, textarea:disabled {
    background: var(--surface-2);
    color: var(--muted);
    cursor: not-allowed;
}

/* Поиск с иконкой */
.search {
    position: relative;
    flex: 1 1 260px;
    min-width: 0;
}
.search svg {
    position: absolute;
    left: 13px;
    top: 50%;
    transform: translateY(-50%);
    width: 17px;
    height: 17px;
    color: var(--muted-soft);
    pointer-events: none;
}
.search input { padding-left: 40px; }

/* Загрузка файла */
input[type=file] {
    width: 100%;
    padding: 9px 13px;
    border: 1px dashed var(--border-strong);
    border-radius: var(--radius-sm);
    background: var(--surface-2);
    color: var(--muted);
    font: inherit;
    font-size: 14px;
    cursor: pointer;
    transition: border-color .15s var(--ease), background .15s var(--ease);
}
input[type=file]:hover { border-color: var(--accent); background: var(--accent-soft); }
input[type=file]::file-selector-button {
    margin-right: 12px;
    padding: 6px 13px;
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-xs);
    background: var(--surface);
    color: var(--text-2);
    font: inherit;
    font-size: 13px;
    font-weight: 580;
    cursor: pointer;
}
input[type=file]::file-selector-button:hover { background: var(--surface-3); }

/* Флажки и переключатели */
input[type=checkbox], input[type=radio] {
    appearance: none;
    width: 18px;
    height: 18px;
    margin: 0;
    flex-shrink: 0;
    border: 1.5px solid var(--border-strong);
    background: var(--surface);
    cursor: pointer;
    transition: background .15s var(--ease), border-color .15s var(--ease), box-shadow .15s var(--ease);
}
input[type=checkbox] { border-radius: 5px; }
input[type=radio] { border-radius: 50%; }
input[type=checkbox]:hover, input[type=radio]:hover { border-color: var(--accent); }
input[type=checkbox]:checked, input[type=radio]:checked {
    background-color: var(--brand-600);
    border-color: var(--brand-600);
}
input[type=checkbox]:checked {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M20 6 9 17l-5-5'/%3E%3C/svg%3E");
    background-size: 12px;
    background-position: center;
    background-repeat: no-repeat;
}
input[type=radio]:checked { box-shadow: inset 0 0 0 3.5px var(--surface); }
input[type=checkbox]:focus-visible, input[type=radio]:focus-visible {
    outline: none;
    box-shadow: var(--ring);
}

.checkline {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
}
.checkline label { margin: 0; font-weight: 450; font-size: 14.5px; cursor: pointer; }
.checkline input[type=text] { flex: 1; }

.field-error {
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--danger);
    font-size: 13px;
    font-weight: 500;
    margin-top: 6px;
}
.field-error::before { content: "⚠"; font-size: 12px; }

/* -------------------------------------------------------------------------
   10. Варианты ответа теста
   ------------------------------------------------------------------------- */
.opt-list { display: flex; flex-direction: column; gap: 9px; margin-top: 14px; }
.opt {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 15px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    cursor: pointer;
    transition: border-color .15s var(--ease), background .15s var(--ease), transform .12s var(--ease);
}
.opt:hover { border-color: var(--brand-300); background: var(--surface-hover); }
.opt:active { transform: scale(.995); }
.opt > .opt-text { flex: 1; font-size: 14.5px; }
.opt:has(input:checked) {
    border-color: var(--accent);
    background: var(--accent-soft);
}
/* Разбор попытки: правильный / выбранный, но неверный */
.opt-correct {
    border-color: var(--success-line);
    background: var(--success-soft);
}
.opt-wrong {
    border-color: var(--danger-line);
    background: var(--danger-soft);
}
.opt-mark {
    display: grid;
    place-items: center;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    flex-shrink: 0;
    font-size: 13px;
    font-weight: 700;
}
.opt-correct .opt-mark { background: var(--success); color: #fff; }
.opt-wrong .opt-mark { background: var(--danger); color: #fff; }

/* Нумерованный кружок вопроса */
.q-num {
    display: grid;
    place-items: center;
    width: 28px;
    height: 28px;
    border-radius: 9px;
    background: var(--accent-soft);
    color: var(--accent-dark);
    font-size: 13px;
    font-weight: 700;
    flex-shrink: 0;
    font-variant-numeric: tabular-nums;
}

/* -------------------------------------------------------------------------
   11. Сообщения
   ------------------------------------------------------------------------- */
.alert {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 13px 16px;
    border: 1px solid;
    border-radius: var(--radius);
    margin-bottom: 20px;
    font-size: 14.5px;
    font-weight: 500;
    box-shadow: var(--shadow-xs);
    animation: alert-in .3s var(--ease) both;
}
@keyframes alert-in {
    from { opacity: 0; transform: translateY(-6px); }
    to   { opacity: 1; transform: none; }
}
.alert svg { width: 19px; height: 19px; flex-shrink: 0; margin-top: 1px; }
.alert > span { flex: 1; }
.alert-close {
    padding: 0;
    border: 0;
    background: none;
    color: currentColor;
    opacity: .55;
    cursor: pointer;
    line-height: 1;
    flex-shrink: 0;
}
.alert-close:hover { opacity: 1; }
.alert-close svg { width: 15px; height: 15px; margin: 0; }

.alert-success { background: var(--success-soft); border-color: var(--success-line); color: var(--success); }
.alert-error   { background: var(--danger-soft);  border-color: var(--danger-line);  color: var(--danger); }
.alert-info    { background: var(--info-soft);    border-color: var(--info-line);    color: var(--info); }
.alert-warning { background: var(--warning-soft); border-color: var(--warning-line); color: var(--warning); }

/* -------------------------------------------------------------------------
   12. Метки
   ------------------------------------------------------------------------- */
.tag {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 3px 10px;
    border-radius: var(--radius-pill);
    font-size: 12px;
    font-weight: 620;
    letter-spacing: .01em;
    line-height: 1.5;
    white-space: nowrap;
    background: var(--surface-3);
    color: var(--muted);
    border: 1px solid transparent;
}
.tag svg { width: 13px; height: 13px; }
.tag-success { background: var(--success-soft); color: var(--success); border-color: var(--success-line); }
.tag-danger  { background: var(--danger-soft);  color: var(--danger);  border-color: var(--danger-line); }
.tag-warning { background: var(--warning-soft); color: var(--warning); border-color: var(--warning-line); }
.tag-info    { background: var(--info-soft);    color: var(--info);    border-color: var(--info-line); }
/* Метка на цветной обложке курса */
.tag-onCover {
    background: rgba(255, 255, 255, .22);
    color: #fff;
    border-color: rgba(255, 255, 255, .3);
    backdrop-filter: blur(6px);
}

/* -------------------------------------------------------------------------
   13. Прогресс
   ------------------------------------------------------------------------- */
.progress {
    height: 8px;
    background: var(--surface-3);
    border-radius: var(--radius-pill);
    overflow: hidden;
    margin: 8px 0;
}
.progress-sm { height: 6px; }
.progress-bar {
    height: 100%;
    border-radius: var(--radius-pill);
    background: linear-gradient(90deg, var(--brand-500), var(--brand-400));
    transition: width .6s var(--ease);
}
.progress-bar.full { background: linear-gradient(90deg, #10b981, #34d399); }

/* Строка «Прогресс … 60 %» с числом справа */
.progress-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    font-size: 13px;
    font-weight: 600;
    color: var(--muted);
}
.progress-row .pct { color: var(--text); font-variant-numeric: tabular-nums; }

/* Кольцевой индикатор: --val задаётся инлайново как процент */
.ring {
    --val: 0;
    --size: 92px;
    position: relative;
    width: var(--size);
    height: var(--size);
    flex-shrink: 0;
    border-radius: 50%;
    background:
        conic-gradient(var(--brand-500) calc(var(--val) * 1%), var(--surface-3) 0);
    display: grid;
    place-items: center;
}
.ring.full { background: conic-gradient(#10b981 calc(var(--val) * 1%), var(--surface-3) 0); }
.ring::after {
    content: "";
    position: absolute;
    inset: 9px;
    border-radius: 50%;
    background: var(--surface);
}
.ring-label {
    position: relative;
    z-index: 1;
    font-size: 19px;
    font-weight: 700;
    letter-spacing: -.03em;
    color: var(--text);
    font-variant-numeric: tabular-nums;
}

/* -------------------------------------------------------------------------
   14. Таблицы
   ------------------------------------------------------------------------- */
.table-wrap {
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: auto;
    background: var(--surface);
    box-shadow: var(--shadow-sm);
    max-width: 100%;
}
table { width: 100%; border-collapse: collapse; background: transparent; }
th, td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
    font-size: 14px;
    vertical-align: middle;
}
thead th {
    position: sticky;
    top: 0;
    z-index: 1;
    font-size: 12px;
    font-weight: 650;
    letter-spacing: .05em;
    text-transform: uppercase;
    color: var(--muted);
    background: var(--surface-2);
    white-space: nowrap;
}
tbody tr { transition: background .12s var(--ease); }
tbody tr:hover { background: var(--surface-hover); }
tbody tr:last-child td { border-bottom: none; }
tfoot th {
    background: var(--surface-2);
    font-size: 13.5px;
    font-weight: 700;
    color: var(--text);
    text-transform: none;
    letter-spacing: 0;
    border-bottom: none;
    border-top: 2px solid var(--border-strong);
}
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
td.muted { color: var(--muted); }

/* Ячейка «Студент» с аватаром */
.cell-user { display: flex; align-items: center; gap: 10px; min-width: 0; }
.cell-user .avatar { width: 30px; height: 30px; font-size: 11px; }
.cell-user strong { font-weight: 580; font-size: 14px; }

/* -------------------------------------------------------------------------
   15. Списки уроков / материалов
   ------------------------------------------------------------------------- */
.lesson-list { list-style: none; padding: 0; margin: 12px 0 0; }
.lesson-list li {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 11px 12px;
    margin: 0 -12px;
    border-radius: var(--radius-sm);
    border-bottom: 1px solid var(--border);
    transition: background .12s var(--ease);
}
.lesson-list li:hover { background: var(--surface-hover); }
.lesson-list li:last-child { border-bottom: none; }
.lesson-list a { font-weight: 520; color: var(--text); }
.lesson-list a:hover { color: var(--accent); }
.lesson-list .spacer { margin-left: auto; }

/* Кружок статуса урока: пройден / нет */
.check {
    display: grid;
    place-items: center;
    width: 22px;
    height: 22px;
    flex-shrink: 0;
    border-radius: 50%;
    border: 1.5px solid var(--border-strong);
    color: transparent;
    font-size: 12px;
    font-weight: 700;
    line-height: 1;
}
.check.is-done {
    background: var(--success);
    border-color: var(--success);
    color: #fff;
}

/* Иконка типа элемента слева в списке */
.item-icon {
    display: grid;
    place-items: center;
    width: 34px;
    height: 34px;
    flex-shrink: 0;
    border-radius: 10px;
    background: var(--accent-soft);
    color: var(--accent-dark);
}
.item-icon svg { width: 17px; height: 17px; }
.item-icon.icon-file    { background: var(--surface-3); color: var(--muted); }
.item-icon.icon-quiz    { background: var(--warning-soft); color: var(--warning); }
.item-icon.icon-task    { background: var(--info-soft); color: var(--info); }
.item-icon.icon-success { background: var(--success-soft); color: var(--success); }

/* Двухстрочная запись списка: заголовок + подпись */
.item-text { min-width: 0; flex: 1; }
.item-text > a, .item-text > strong { display: block; font-size: 14.5px; font-weight: 550; }
.item-text small { display: block; color: var(--muted); font-size: 13px; }

/* Материал урока: сохраняем переносы, читаемая колонка */
.lesson-body {
    white-space: pre-wrap;
    font-size: 15.5px;
    line-height: 1.75;
    color: var(--text-2);
    overflow-wrap: anywhere;
}

/* -------------------------------------------------------------------------
   16. Модуль курса (аккордеон-подобная группа)
   ------------------------------------------------------------------------- */
.module {
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: var(--surface);
    box-shadow: var(--shadow-sm);
    margin-bottom: 14px;
    overflow: hidden;
}
.module-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    flex-wrap: wrap;
    padding: 16px 20px;
    background: var(--surface-2);
    border-bottom: 1px solid var(--border);
}
.module-head h3 { margin: 0; display: flex; align-items: center; gap: 10px; }
.module-body { padding: 6px 20px 16px; }
.module-body .lesson-list { margin-top: 0; }

/* -------------------------------------------------------------------------
   17. Пустые состояния
   ------------------------------------------------------------------------- */
.empty {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 52px 24px;
    border: 1px dashed var(--border-strong);
    border-radius: var(--radius-lg);
    background: color-mix(in srgb, var(--surface) 60%, transparent);
    color: var(--muted);
}
.empty-icon {
    display: grid;
    place-items: center;
    width: 56px;
    height: 56px;
    margin-bottom: 16px;
    border-radius: 18px;
    background: var(--accent-soft);
    color: var(--accent);
}
.empty-icon svg { width: 26px; height: 26px; }
.empty h3 { margin: 0 0 6px; color: var(--text); font-size: 16.5px; }
.empty p { margin: 0; font-size: 14.5px; max-width: 46ch; }
.empty .actions { margin-top: 20px; }
.empty-sm { padding: 32px 20px; }

/* -------------------------------------------------------------------------
   18. Главная: герой
   ------------------------------------------------------------------------- */
.hero {
    position: relative;
    padding: 56px 0 48px;
    text-align: center;
    overflow: hidden;
}
.hero h1 {
    font-size: clamp(34px, 6vw, 56px);
    line-height: 1.06;
    letter-spacing: -.045em;
    max-width: 15ch;
    margin: 18px auto 0;
}
.hero .grad {
    background: linear-gradient(100deg, var(--brand-500), var(--accent-500) 90%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}
.hero .lead { margin: 20px auto 0; font-size: 18px; max-width: 54ch; }
.hero .actions { margin-top: 30px; justify-content: center; }

.hero-points {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 18px;
    margin: 52px 0 12px;
}
.hero-point {
    padding: 22px;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: color-mix(in srgb, var(--surface) 75%, transparent);
    backdrop-filter: blur(6px);
    text-align: left;
}
.hero-point .item-icon { margin-bottom: 12px; }
.hero-point h3 { margin: 0 0 4px; font-size: 15.5px; }
.hero-point p { margin: 0; color: var(--muted); font-size: 14px; }

/* -------------------------------------------------------------------------
   19. Вход и регистрация
   ------------------------------------------------------------------------- */
.auth-shell {
    display: grid;
    grid-template-columns: 1fr;
    gap: 40px;
    align-items: center;
    max-width: 1000px;
    margin: 24px auto;
}
.auth-card {
    width: 100%;
    max-width: 440px;
    margin: 0 auto;
    padding: 32px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}
.auth-card h1 { font-size: 26px; }
.auth-card .lead { font-size: 14.5px; margin-top: 6px; margin-bottom: 26px; }
.auth-foot {
    margin-top: 22px;
    padding-top: 18px;
    border-top: 1px solid var(--border);
    text-align: center;
    font-size: 14px;
    color: var(--muted);
}
.auth-foot a { font-weight: 600; }

/* Левая колонка на широком экране */
.auth-aside { display: none; }
.auth-aside h2 { font-size: 30px; margin: 0 0 14px; letter-spacing: -.035em; }
.auth-aside .lead { margin-left: 0; }
.auth-aside ul { list-style: none; padding: 0; margin: 28px 0 0; display: grid; gap: 16px; }
.auth-aside li { display: flex; gap: 13px; align-items: flex-start; }
.auth-aside li strong { display: block; font-size: 14.5px; }
.auth-aside li span { font-size: 13.5px; color: var(--muted); }

/* Выбор роли при регистрации */
.role-picker { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.role-opt {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 14px 10px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    text-align: center;
    cursor: pointer;
    transition: border-color .15s var(--ease), background .15s var(--ease);
}
.role-opt:hover { border-color: var(--brand-300); background: var(--surface-hover); }
.role-opt:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); }
.role-opt input { position: absolute; opacity: 0; pointer-events: none; }
.role-opt svg { width: 20px; height: 20px; color: var(--accent); }
.role-opt span { font-size: 14px; font-weight: 580; color: var(--text); }

/* -------------------------------------------------------------------------
   20. Страницы ошибок
   ------------------------------------------------------------------------- */
.error-page {
    max-width: 520px;
    margin: 60px auto;
    text-align: center;
}
.error-code {
    font-size: 88px;
    font-weight: 800;
    line-height: 1;
    letter-spacing: -.05em;
    background: linear-gradient(140deg, var(--brand-500), var(--accent-500));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}
.error-page h1 { margin: 14px 0 10px; }
.error-page .actions { margin-top: 26px; justify-content: center; }

/* -------------------------------------------------------------------------
   21. Навигация по урокам
   ------------------------------------------------------------------------- */
.pager {
    display: flex;
    justify-content: space-between;
    gap: 14px;
    margin-top: 32px;
}
.pager-link {
    display: flex;
    align-items: center;
    gap: 12px;
    flex: 0 1 320px;
    padding: 14px 18px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    box-shadow: var(--shadow-xs);
    color: var(--text);
    transition: border-color .15s var(--ease), box-shadow .15s var(--ease), transform .15s var(--ease);
}
.pager-link:hover {
    border-color: var(--accent);
    box-shadow: var(--shadow-sm);
    transform: translateY(-1px);
    color: var(--text);
}
.pager-link svg { width: 18px; height: 18px; color: var(--muted); flex-shrink: 0; }
.pager-link small { display: block; font-size: 12px; color: var(--muted); }
.pager-link strong { display: block; font-size: 14.5px; font-weight: 580; }
.pager-next { margin-left: auto; text-align: right; flex-direction: row-reverse; }

/* Липкая полоса «Отметить как пройденный» */
.lesson-actions {
    display: flex;
    align-items: center;
    gap: 14px;
    flex-wrap: wrap;
    padding: 16px 20px;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: var(--surface);
    box-shadow: var(--shadow-sm);
}
.lesson-actions form { margin: 0; }

/* -------------------------------------------------------------------------
   22. Подвал
   ------------------------------------------------------------------------- */
footer {
    border-top: 1px solid var(--border);
    padding: 24px 0;
    color: var(--muted);
    font-size: 13.5px;
    background: color-mix(in srgb, var(--surface) 70%, transparent);
}
footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}
footer .brand { font-size: 14px; }
footer .brand-mark { width: 26px; height: 26px; border-radius: 8px; }
footer .brand-mark svg { width: 15px; height: 15px; }

/* Переключатель языка */
.lang-switch {
    display: inline-flex;
    padding: 3px;
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    background: var(--surface-2);
}
.lang-switch a {
    padding: 4px 13px;
    border-radius: var(--radius-pill);
    font-size: 13px;
    font-weight: 580;
    color: var(--muted);
    transition: background .15s var(--ease), color .15s var(--ease);
}
.lang-switch a:hover { color: var(--text); }
.lang-switch a.is-active { background: var(--surface); color: var(--text); box-shadow: var(--shadow-xs); }

/* -------------------------------------------------------------------------
   23. Утилиты
   ------------------------------------------------------------------------- */
.sr-only {
    position: absolute;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
    border: 0;
}
.stack { display: flex; flex-direction: column; gap: 18px; }
.stack-sm { display: flex; flex-direction: column; gap: 10px; }
.row { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.spacer { margin-left: auto; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.mt-2 { margin-top: 20px; }
.mb-2 { margin-bottom: 20px; }
.mb-3 { margin-bottom: 28px; }
.nowrap { white-space: nowrap; }
.divider { height: 1px; border: 0; background: var(--border); margin: 24px 0; }

/* Опасная зона — удаление курса и подобное */
.danger-zone {
    border-color: var(--danger-line);
    background: color-mix(in srgb, var(--danger-soft) 55%, var(--surface));
}
.danger-zone h3 { color: var(--danger); }

/* -------------------------------------------------------------------------
   24. Адаптив
   ------------------------------------------------------------------------- */
@media (min-width: 900px) {
    .auth-shell { grid-template-columns: 1.05fr .95fr; }
    .auth-aside { display: block; }
    .auth-card { margin: 0; }
}

@media (max-width: 980px) {
    .nav-toggle { display: grid; }

    /* Навигация уезжает в выдвижную панель */
    .nav {
        position: fixed;
        inset: var(--header-h) 0 auto 0;
        z-index: 45;
        flex-direction: column;
        align-items: stretch;
        gap: 4px;
        margin: 0;
        padding: 12px 16px 18px;
        background: var(--surface);
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-lg);
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px);
        transition: opacity .2s var(--ease), transform .2s var(--ease), visibility .2s;
    }
    .nav.is-open { opacity: 1; visibility: visible; transform: none; }
    .nav a { padding: 11px 14px; font-size: 15px; }
    .usermenu-name { display: none; }
    .usermenu-trigger { padding: 4px; }
    .usermenu-trigger .chev { display: none; }
}

@media (max-width: 720px) {
    .container { padding: 0 16px; }
    main { padding: 22px 0 56px; }
    h2 { font-size: 19px; margin: 32px 0 14px; }
    .card { padding: 18px; border-radius: var(--radius); }
    .auth-card { padding: 24px 20px; }
    .page-head { gap: 14px; margin-bottom: 22px; }
    .page-head .actions { width: 100%; }
    .pager { flex-direction: column; }
    .pager-link { flex: 1; }
    .pager-next { margin-left: 0; }
    .grid { grid-template-columns: 1fr; }
    .stat-grid { grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 10px; }
    .stat { padding: 14px 16px; }
    .stat-value { font-size: 23px; }
    th, td { padding: 10px 12px; }
    footer .container { justify-content: center; text-align: center; }
    .hero { padding: 36px 0 32px; }
    .hero .actions .btn { flex: 1 1 auto; }
}

/* -------------------------------------------------------------------------
   25. Уважение к настройкам пользователя и печать
   ------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: .001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: .001ms !important;
        scroll-behavior: auto !important;
    }
}

@media print {
    .topbar, footer, .actions, .pager, .nav-toggle { display: none !important; }
    body { background: #fff; }
    .card, .table-wrap { box-shadow: none; border-color: #ccc; }
}