/* =====================================================================
   K-12 Design System (trung tính dùng chung)
   Bố cục mới: shell sidebar + topbar + nội dung dạng thẻ.
   Chỉ áp dụng khi <html data-ui="k12">. Giao diện cũ nằm ở *.classic.html.
   Nạp SAU theme.css để ưu tiên token của bố cục mới.
   ===================================================================== */

html[data-ui="k12"] {
    --k12-radius: 16px;
    --k12-radius-sm: 11px;
    --k12-gap: 16px;
    --k12-sidebar-w: 248px;
    --k12-topbar-h: 62px;

    --k12-primary: #4f46e5;
    --k12-primary-strong: #4338ca;
    --k12-primary-soft: rgba(79, 70, 229, .10);
    --k12-accent: #0ea5e9;
    --k12-success: #10b981;
    --k12-warn: #d97706;
    --k12-danger: #dc2626;

    --k12-bg: #f4f6fb;
    --k12-surface: #ffffff;
    --k12-surface-2: #f7f9fc;
    --k12-border: #e6eaf1;
    --k12-text: #0f172a;
    --k12-muted: #64748b;
    --k12-sidebar: #ffffff;
    --k12-sidebar-active: #eef1ff;
    --k12-shadow: 0 1px 2px rgba(15, 23, 42, .06), 0 8px 24px -18px rgba(15, 23, 42, .30);
}

html[data-ui="k12"][data-theme="dark"] {
    --k12-primary: #818cf8;
    --k12-primary-strong: #a5b4fc;
    --k12-primary-soft: rgba(129, 140, 248, .16);
    --k12-accent: #38bdf8;
    --k12-success: #34d399;
    --k12-warn: #fbbf24;
    --k12-danger: #f87171;

    --k12-bg: #0e1116;
    --k12-surface: #161a21;
    --k12-surface-2: #1b202a;
    --k12-border: #262c37;
    --k12-text: #e7eaf0;
    --k12-muted: #98a2b3;
    --k12-sidebar: #12151b;
    --k12-sidebar-active: rgba(129, 140, 248, .14);
    --k12-shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 12px 28px -20px rgba(0, 0, 0, .8);
}

html[data-ui="k12"][data-theme],
html[data-ui="k12"][data-theme] body {
    background: var(--k12-bg) !important;
    color: var(--k12-text);
}

html[data-ui="k12"] body {
    min-height: 100vh;
    max-width: 100%;
    overflow-x: clip;
}

html[data-ui="k12"] * { box-sizing: border-box; }

/* ---------- Bố cục tổng ---------- */
.k12-app { display: flex; min-height: 100vh; }

.k12-skip {
    position: fixed; left: 12px; top: -60px; z-index: 200;
    background: var(--k12-primary); color: #fff; padding: 10px 16px; border-radius: 10px;
    transition: top .2s;
}
.k12-skip:focus { top: 12px; }

/* ---------- Sidebar ---------- */
.k12-sidebar {
    position: fixed; inset: 0 auto 0 0; width: var(--k12-sidebar-w); z-index: 60;
    display: flex; flex-direction: column;
    background: var(--k12-sidebar);
    border-right: 1px solid var(--k12-border);
    transform: translateX(-100%);
    transition: transform .24s ease;
}
.k12-app.k12-nav-open .k12-sidebar { transform: translateX(0); }

.k12-brand {
    display: flex; align-items: center; gap: 10px;
    padding: 16px 18px; min-height: var(--k12-topbar-h);
    border-bottom: 1px solid var(--k12-border);
}
.k12-brand-logo {
    width: 38px; height: 38px; border-radius: 11px; flex: none;
    display: grid; place-items: center; overflow: hidden;
    background: linear-gradient(135deg, var(--k12-primary), var(--k12-accent));
    color: #fff; font-weight: 800; font-size: 18px;
}
.k12-brand-logo img { width: 100%; height: 100%; object-fit: contain; }
.k12-brand-name { font-weight: 800; line-height: 1.15; font-size: 15px; }
.k12-brand-slogan { font-size: 11px; color: var(--k12-muted); }

.k12-nav { flex: 1; overflow-y: auto; padding: 12px 10px 20px; }
.k12-nav-group { margin-bottom: 14px; }
.k12-nav-label {
    font-size: 10.5px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase;
    color: var(--k12-muted); padding: 6px 12px;
}
.k12-nav-item {
    display: flex; align-items: center; gap: 11px; width: 100%;
    padding: 10px 12px; margin: 2px 0; border: 0; background: transparent;
    border-radius: 11px; cursor: pointer; text-align: left;
    color: var(--k12-text); font-size: 14px; font-weight: 500; line-height: 1.2;
    transition: background .15s, color .15s;
}
.k12-nav-item:hover { background: var(--k12-surface-2); }
.k12-nav-icon { font-size: 18px; width: 22px; text-align: center; flex: none; }
.k12-nav-item .k12-nav-badge { margin-left: auto; }

/* Trạng thái active: mỗi trang dùng class khác nhau (switchTab cũ) */
html[data-ui="k12"] .k12-nav-item.is-active,
html[data-ui="k12"][data-page="student"] .k12-nav-item.bg-slate-700,
html[data-ui="k12"][data-page="teacher"] .k12-nav-item.bg-indigo-600 {
    background: var(--k12-sidebar-active) !important;
    color: var(--k12-primary) !important;
    font-weight: 700;
}
html[data-ui="k12"] .k12-nav-item.bg-slate-700 .k12-nav-icon,
html[data-ui="k12"] .k12-nav-item.bg-indigo-600 .k12-nav-icon,
html[data-ui="k12"] .k12-nav-item.is-active .k12-nav-icon { filter: none; }
/* Teacher: .bg-slate-700 là mục KHÔNG active -> giữ trung tính */
html[data-ui="k12"][data-page="teacher"] .k12-nav-item.bg-slate-700 {
    background: transparent !important;
    color: var(--k12-text) !important;
    font-weight: 500;
}
html[data-ui="k12"][data-page="teacher"] .k12-nav-item.bg-slate-700:hover { background: var(--k12-surface-2) !important; }

.k12-sidebar-foot { padding: 10px 12px; border-top: 1px solid var(--k12-border); }

/* ---------- Vùng nội dung ---------- */
.k12-body { flex: 1; min-width: 0; display: flex; flex-direction: column; }

.k12-topbar {
    position: sticky; top: 0; z-index: 30;
    display: flex; align-items: center; gap: 12px;
    min-height: var(--k12-topbar-h); padding: 10px 18px;
    background: color-mix(in srgb, var(--k12-surface) 88%, transparent);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--k12-border);
}
.k12-menu-btn {
    display: inline-grid; place-items: center; width: 40px; height: 40px; flex: none;
    border: 1px solid var(--k12-border); background: var(--k12-surface);
    border-radius: 11px; cursor: pointer; font-size: 18px; color: var(--k12-text);
}
.k12-topbar-title { font-size: 16px; font-weight: 800; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.k12-topbar-actions { margin-left: auto; display: flex; align-items: center; gap: 8px; }

.k12-userchip {
    display: inline-flex; align-items: center; gap: 8px; max-width: 46vw;
    padding: 6px 12px 6px 6px; border: 1px solid var(--k12-border);
    background: var(--k12-surface); border-radius: 999px; cursor: pointer; color: var(--k12-text);
}
.k12-userchip .k12-avatar {
    width: 30px; height: 30px; border-radius: 999px; flex: none;
    display: grid; place-items: center; font-weight: 800; font-size: 13px; color: #fff;
    background: linear-gradient(135deg, var(--k12-primary), var(--k12-accent));
}
.k12-userchip .k12-user-name { font-size: 13px; font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.k12-iconbtn {
    display: inline-grid; place-items: center; width: 40px; height: 40px; flex: none;
    border: 1px solid var(--k12-border); background: var(--k12-surface); color: var(--k12-text);
    border-radius: 11px; cursor: pointer; font-size: 17px; position: relative;
}
.k12-iconbtn:hover { background: var(--k12-surface-2); }

.k12-main { flex: 1; min-width: 0; padding: 22px 18px 64px; }
.k12-page { max-width: 1180px; margin: 0 auto; width: 100%; }
.k12-page.wide { max-width: 100%; }
.k12-page-head { margin-bottom: 18px; }
.k12-page-title { font-size: 22px; font-weight: 800; letter-spacing: -.01em; }
.k12-page-sub { color: var(--k12-muted); font-size: 13.5px; margin-top: 3px; }

/* ---------- Thẻ & thành phần ---------- */
.k12-card {
    background: var(--k12-surface); border: 1px solid var(--k12-border);
    border-radius: var(--k12-radius); box-shadow: var(--k12-shadow);
}
.k12-card-pad { padding: 18px; }
.k12-card-head {
    display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
    padding: 14px 16px; border-bottom: 1px solid var(--k12-border);
}
.k12-card-title { font-size: 15px; font-weight: 700; }
.k12-card-body { padding: 16px; }

.k12-grid { display: grid; gap: var(--k12-gap); }
.k12-grid.cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.k12-grid.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.k12-grid.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 1023px) {
    .k12-grid.cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .k12-grid.cols-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 560px) {
    .k12-grid.cols-2, .k12-grid.cols-3, .k12-grid.cols-4 { grid-template-columns: minmax(0, 1fr); }
}

.k12-btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 7px;
    padding: 10px 16px; border-radius: 11px; border: 1px solid var(--k12-border);
    background: var(--k12-surface); color: var(--k12-text);
    font-size: 14px; font-weight: 600; cursor: pointer; text-decoration: none;
    transition: background .15s, border-color .15s, transform .05s;
}
.k12-btn:hover { background: var(--k12-surface-2); }
.k12-btn:active { transform: translateY(1px); }
.k12-btn-primary {
    background: var(--k12-primary); border-color: var(--k12-primary); color: #fff;
}
.k12-btn-primary:hover { background: var(--k12-primary-strong); border-color: var(--k12-primary-strong); }
.k12-btn-success { background: var(--k12-success); border-color: var(--k12-success); color: #fff; }
.k12-btn-ghost { background: transparent; }
.k12-btn-sm { padding: 7px 12px; font-size: 13px; border-radius: 9px; }
.k12-btn-block { width: 100%; }

.k12-chip {
    display: inline-flex; align-items: center; gap: 5px;
    padding: 3px 10px; border-radius: 999px; font-size: 11.5px; font-weight: 600;
    background: var(--k12-surface-2); border: 1px solid var(--k12-border); color: var(--k12-muted);
}
.k12-chip.primary { background: var(--k12-primary-soft); color: var(--k12-primary); border-color: transparent; }
.k12-chip.success { background: rgba(16, 185, 129, .12); color: var(--k12-success); border-color: transparent; }
.k12-chip.warn { background: rgba(217, 119, 6, .14); color: var(--k12-warn); border-color: transparent; }

.k12-stat {
    background: var(--k12-surface); border: 1px solid var(--k12-border);
    border-radius: var(--k12-radius); padding: 16px;
}
.k12-stat-num { font-size: 26px; font-weight: 800; letter-spacing: -.02em; }
.k12-stat-label { font-size: 12px; color: var(--k12-muted); margin-top: 2px; }

/* ---------- Hero (trang chủ) ---------- */
.k12-hero {
    position: relative; overflow: hidden;
    border-radius: 22px; padding: 34px 30px; margin-bottom: 22px;
    background: linear-gradient(135deg, var(--k12-primary) 0%, #6d28d9 55%, var(--k12-accent) 100%);
    color: #fff;
}
.k12-hero h1 { font-size: clamp(24px, 3.4vw, 34px); font-weight: 900; letter-spacing: -.02em; }
.k12-hero p { opacity: .92; margin-top: 8px; max-width: 620px; font-size: 15px; }
.k12-hero-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 18px; }
.k12-hero .k12-btn-primary { background: #fff; border-color: #fff; color: var(--k12-primary); }
.k12-hero .k12-btn-primary:hover { background: #f1f5f9; border-color: #f1f5f9; }
.k12-hero .k12-btn-ghost { color: #fff; border-color: rgba(255, 255, 255, .5); }
.k12-hero .k12-btn-ghost:hover { background: rgba(255, 255, 255, .12); }

.k12-search {
    display: flex; align-items: center; gap: 8px;
    background: var(--k12-surface); border: 1px solid var(--k12-border);
    border-radius: 13px; padding: 4px 4px 4px 14px;
}
.k12-search input {
    flex: 1; min-width: 0; border: 0; background: transparent; color: var(--k12-text);
    font-size: 14px; padding: 9px 4px; outline: none;
}

/* ---------- Bảng lọc (catalog) ---------- */
.k12-filters { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.k12-filters select,
.k12-filters input {
    background: var(--k12-surface) !important; color: var(--k12-text) !important;
    border: 1px solid var(--k12-border) !important; border-radius: 10px;
    padding: 8px 10px; font-size: 13px; outline: none;
}
html[data-ui="k12"] select option { background: var(--k12-surface); color: var(--k12-text); }

/* ---------- Drawer/modal auth (trang chủ) ---------- */
html[data-ui="k12"] #authAside {
    position: fixed !important; z-index: 90; right: 0; top: 0; bottom: 0; left: auto !important;
    width: min(420px, 100%); max-height: none !important; height: 100%;
    overflow-y: auto; padding: 0; margin: 0;
    background: var(--k12-bg);
    border-left: 1px solid var(--k12-border);
    transform: translateX(105%); transition: transform .26s ease; visibility: hidden;
    box-shadow: -20px 0 50px -30px rgba(0, 0, 0, .6);
}
html[data-ui="k12"] #authAside.sheet-open { transform: translateX(0); visibility: visible; }
html[data-ui="k12"] #authBackdrop { z-index: 85; }
html[data-ui="k12"] #authFab { display: inline-flex !important; }
html[data-ui="k12"] #sessionPanel:not(.hidden) { display: flex !important; align-items: center; gap: 8px; }
html[data-ui="k12"] #sessionPanel:not(.hidden) ~ #authFab { display: none !important; }

/* Nhãn trường trong form auth cho dễ đọc trên nền sáng/tối */
html[data-ui="k12"] #authCard { background: var(--k12-surface); border: 1px solid var(--k12-border); border-radius: var(--k12-radius); overflow: hidden; color: var(--k12-text); }
html[data-ui="k12"] #sessionPanel { background: var(--k12-surface); border: 1px solid var(--k12-border); border-radius: var(--k12-radius); }

/* Nút đổi giao diện (themeBtn) canh phải để không đè sidebar */
html[data-ui="k12"] #themeSwitcher { left: auto !important; right: 16px !important; bottom: 16px !important; }

/* ---------- Scrim (mobile nav) ---------- */
.k12-scrim {
    position: fixed; inset: 0; z-index: 55; background: rgba(2, 6, 23, .55);
    opacity: 0; pointer-events: none; transition: opacity .2s;
}
.k12-app.k12-nav-open .k12-scrim { opacity: 1; pointer-events: auto; }

/* ---------- Bảng (dùng trong nội dung) ---------- */
html[data-ui="k12"] .k12-main table { border-collapse: collapse; }
html[data-ui="k12"] .k12-main img,
html[data-ui="k12"] .k12-main iframe,
html[data-ui="k12"] .k12-main video,
html[data-ui="k12"] .k12-main canvas,
html[data-ui="k12"] .k12-main svg,
html[data-ui="k12"] .k12-main table,
html[data-ui="k12"] .k12-main pre { max-width: 100%; }

/* ---------- Responsive ---------- */
@media (min-width: 1024px) {
    .k12-sidebar { transform: translateX(0); }
    .k12-body { margin-left: var(--k12-sidebar-w); }
    .k12-menu-btn { display: none; }
    .k12-main { padding: 28px 30px 72px; }
}

/* ----- Làm dịu các thẻ nội dung cũ để hoà với bố cục mới ----- */
html[data-ui="k12"] .k12-main .rounded-2xl.bg-slate-800,
html[data-ui="k12"] .k12-main .rounded-xl.bg-slate-800,
html[data-ui="k12"] .k12-main .bg-slate-800 { background-color: var(--k12-surface) !important; }
html[data-ui="k12"] .k12-main .bg-slate-900,
html[data-ui="k12"] .k12-main .bg-slate-900\/60 { background-color: var(--k12-surface-2) !important; }
html[data-ui="k12"] .k12-main .border-slate-700,
html[data-ui="k12"] .k12-main .border-slate-600 { border-color: var(--k12-border) !important; }

@media print {
    html[data-ui="k12"] .k12-sidebar,
    html[data-ui="k12"] .k12-topbar,
    html[data-ui="k12"] #themeSwitcher { display: none !important; }
    html[data-ui="k12"] .k12-body { margin-left: 0 !important; }
}