/* ============================================================
 * Shared theme — admin / teacher / student web apps  (v2)
 * Professional, clean & airy dashboard. Neutral surfaces + green accent.
 * Same class names as before — refined, modern visuals.
 * ============================================================ */
:root{
  --bg:#f5f7fb; --surface:#ffffff; --surface-2:#f8fafc;
  --border:#e9edf3; --border-strong:#d8dee6;
  --text:#0f172a; --muted:#64748b; --faint:#94a3b8;
  --brand:#16a34a; --brand-dark:#15803d; --brand-soft:#f0fdf4;
  --blue:#0ea5e9; --blue-soft:#f0f9ff;
  --violet:#7c3aed; --violet-soft:#f5f3ff;
  --amber:#d97706; --amber-soft:#fffbeb;
  --red:#dc2626; --red-soft:#fef2f2;
  --radius:10px; --radius-lg:16px;
  --shadow:0 1px 2px rgba(16,24,40,.04),0 1px 3px rgba(16,24,40,.05);
  --shadow-md:0 6px 16px rgba(16,24,40,.08),0 2px 6px rgba(16,24,40,.04);
  --shadow-lg:0 18px 44px rgba(16,24,40,.16);
  --sidebar:250px;
  --font:'DM Sans',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{font-family:var(--font);background:var(--bg);color:var(--text);font-size:14px;line-height:1.55;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer}
input,select,textarea{font-family:inherit;font-size:14px}
::selection{background:rgba(22,163,74,.18)}
*{scrollbar-width:thin;scrollbar-color:#cbd5e1 transparent}
*::-webkit-scrollbar{width:9px;height:9px}
*::-webkit-scrollbar-thumb{background:#cbd5e1;border-radius:8px;border:2px solid transparent;background-clip:padding-box}
*::-webkit-scrollbar-thumb:hover{background:#94a3b8;background-clip:padding-box}

/* ---------- layout ---------- */
.layout{display:flex;min-height:100vh}
.sidebar{width:var(--sidebar);background:#ffffff;color:var(--muted);flex-shrink:0;display:flex;flex-direction:column;position:fixed;inset:0 auto 0 0;height:100vh;z-index:40;transition:transform .25s;border-right:1px solid var(--border);box-shadow:2px 0 14px rgba(16,24,40,.03)}
.sidebar-brand{display:flex;align-items:center;gap:11px;padding:18px 20px;border-bottom:1px solid var(--border);cursor:default}
.sidebar-brand .mark{width:38px;height:38px;border-radius:11px;background:linear-gradient(135deg,#22c55e,#16a34a);display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:17px;box-shadow:0 6px 16px rgba(34,197,94,.32);transition:transform .35s cubic-bezier(.2,.8,.2,1),box-shadow .35s}
.sidebar-brand:hover .mark{transform:rotate(-8deg) scale(1.09);box-shadow:0 10px 22px rgba(34,197,94,.45)}
.sidebar-brand .name{font-weight:700;color:var(--text);font-size:15px;line-height:1.15}
.sidebar-brand .role-pill{font-size:10px;color:var(--brand-dark);text-transform:uppercase;letter-spacing:1.2px;font-weight:700;margin-top:2px}
.nav{flex:1;overflow-y:auto;padding:14px 12px}
.nav>*{animation:navIn .45s cubic-bezier(.2,.8,.2,1) backwards}
.nav>*:nth-child(1){animation-delay:.03s}.nav>*:nth-child(2){animation-delay:.06s}.nav>*:nth-child(3){animation-delay:.09s}
.nav>*:nth-child(4){animation-delay:.12s}.nav>*:nth-child(5){animation-delay:.15s}.nav>*:nth-child(6){animation-delay:.18s}
.nav>*:nth-child(7){animation-delay:.21s}.nav>*:nth-child(8){animation-delay:.24s}.nav>*:nth-child(9){animation-delay:.27s}
.nav>*:nth-child(10){animation-delay:.30s}.nav>*:nth-child(11){animation-delay:.33s}.nav>*:nth-child(12){animation-delay:.36s}
.nav>*:nth-child(n+13){animation-delay:.39s}
.nav-group{margin-bottom:3px}
.nav-item{position:relative;display:flex;align-items:center;gap:12px;padding:10px 13px;border-radius:10px;color:#475569;font-size:13.5px;font-weight:500;cursor:pointer;transition:background .18s,color .18s,transform .18s,box-shadow .18s;white-space:nowrap}
.nav-item i{width:18px;text-align:center;font-size:15px;opacity:.85;transition:transform .2s cubic-bezier(.2,.8,.2,1),color .18s,opacity .18s}
.nav-item:hover{background:var(--surface-2);color:var(--text);transform:translateX(3px)}
.nav-item:hover i{transform:scale(1.18);color:var(--brand)}
.nav-item:active{transform:translateX(1px) scale(.99)}
.nav-item.active{background:linear-gradient(90deg,var(--brand-soft),rgba(240,253,244,.35));color:var(--brand-dark);font-weight:600;box-shadow:inset 0 0 0 1px rgba(22,163,74,.10)}
.nav-item.active i{opacity:1;color:var(--brand);transform:scale(1.08)}
.nav-item.active::before{content:"";position:absolute;left:-12px;top:50%;transform:translateY(-50%) scaleY(1);width:3px;height:22px;border-radius:0 3px 3px 0;background:var(--brand);box-shadow:0 0 8px rgba(22,163,74,.5);transform-origin:center;animation:barGrow .28s cubic-bezier(.2,.8,.2,1) both}
.nav-sub{margin:2px 0 6px 32px;display:none;flex-direction:column;gap:1px;border-left:1px solid var(--border);padding-left:8px}
.nav-group.open .nav-sub{display:flex}
.nav-group.open .nav-sub a{animation:subIn .3s ease backwards}
.nav-group.open .nav-sub a:nth-child(1){animation-delay:.02s}.nav-group.open .nav-sub a:nth-child(2){animation-delay:.05s}
.nav-group.open .nav-sub a:nth-child(3){animation-delay:.08s}.nav-group.open .nav-sub a:nth-child(4){animation-delay:.11s}
.nav-group.open .nav-sub a:nth-child(5){animation-delay:.14s}.nav-group.open .nav-sub a:nth-child(n+6){animation-delay:.17s}
.nav-sub a{padding:8px 11px;border-radius:8px;font-size:12.5px;color:var(--muted);transition:background .18s,color .18s,transform .18s}
.nav-sub a:hover{background:var(--surface-2);color:var(--text);transform:translateX(3px)}
.nav-sub a.active{color:var(--brand-dark);background:var(--brand-soft);font-weight:600}
.nav-caret{margin-left:auto;font-size:10px;opacity:.55;transition:transform .25s cubic-bezier(.2,.8,.2,1)}
.nav-group.open .nav-caret{transform:rotate(180deg)}
.sidebar-foot{padding:12px;border-top:1px solid var(--border)}
.logout-btn{display:flex;align-items:center;gap:10px;width:100%;padding:11px 12px;border:1px solid var(--border);background:var(--surface-2);color:var(--muted);border-radius:10px;font-size:13px;font-weight:600;transition:background .18s,color .18s,border-color .18s,transform .18s,box-shadow .18s}
.logout-btn i{transition:transform .2s cubic-bezier(.2,.8,.2,1)}
.logout-btn:hover{background:var(--red);border-color:var(--red);color:#fff;transform:translateY(-1px);box-shadow:0 6px 16px rgba(220,38,38,.28)}
.logout-btn:hover i{transform:translateX(3px)}
.logout-btn:active{transform:translateY(0)}
@keyframes navIn{from{opacity:0;transform:translateX(-12px)}to{opacity:1;transform:none}}
@keyframes subIn{from{opacity:0;transform:translateX(-8px)}to{opacity:1;transform:none}}
@keyframes barGrow{from{transform:translateY(-50%) scaleY(0)}to{transform:translateY(-50%) scaleY(1)}}
@media(prefers-reduced-motion:reduce){
  .nav>*,.nav-group.open .nav-sub a,.nav-item.active::before{animation:none}
  .nav-item:hover,.nav-sub a:hover,.logout-btn:hover,.sidebar-brand:hover .mark{transform:none}
}

.main{flex:1;margin-left:var(--sidebar);display:flex;flex-direction:column;min-width:0}
.topbar{height:64px;background:rgba(255,255,255,.82);backdrop-filter:saturate(180%) blur(12px);border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 26px;position:sticky;top:0;z-index:30}
.topbar h1{font-size:18px;font-weight:600;margin:0;letter-spacing:-.2px}
.topbar-right{display:flex;align-items:center;gap:14px}
.bell{position:relative;width:40px;height:40px;border-radius:11px;border:1px solid var(--border);background:var(--surface);display:flex;align-items:center;justify-content:center;color:var(--muted);transition:background .15s,border-color .15s}
.bell:hover{background:var(--surface-2);border-color:var(--border-strong)}
.bell .dot{position:absolute;top:-5px;right:-5px;min-width:18px;height:18px;padding:0 4px;border-radius:9px;background:var(--red);color:#fff;font-size:10px;font-weight:700;display:flex;align-items:center;justify-content:center;border:2px solid #fff}
.avatar{width:40px;height:40px;border-radius:50%;background:var(--brand-soft);color:var(--brand-dark);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px;border:1px solid #d3f4dd}
.user-mini{display:flex;align-items:center;gap:10px}
.user-mini .nm{font-weight:600;font-size:13.5px;line-height:1.1}
.user-mini .rl{font-size:11px;color:var(--faint)}
.hamburger{display:none;width:40px;height:40px;border-radius:11px;border:1px solid var(--border);background:var(--surface);align-items:center;justify-content:center}
.content{padding:26px;flex:1;max-width:1440px;width:100%}

/* ---------- hero / page header banner ---------- */
.hero{position:relative;overflow:hidden;border-radius:var(--radius-lg);padding:26px 28px;margin-bottom:22px;color:#fff;
      background:linear-gradient(120deg,#15803d 0%,#16a34a 55%,#0ea5e9 160%);box-shadow:0 12px 30px rgba(22,163,74,.22);
      display:flex;align-items:center;justify-content:space-between;gap:18px}
.hero::after{content:"";position:absolute;width:280px;height:280px;border-radius:50%;background:radial-gradient(circle,#ffffff24,transparent 70%);top:-120px;right:-60px}
.hero-text{position:relative;z-index:1}
.hero-text h2{margin:0 0 6px;font-size:23px;font-weight:700;letter-spacing:-.3px}
.hero-text p{margin:0;font-size:14px;color:#eafff2cc}
.hero-ico{position:relative;z-index:1;width:60px;height:60px;border-radius:16px;background:#ffffff22;border:1px solid #ffffff33;display:flex;align-items:center;justify-content:center;font-size:26px;flex-shrink:0}
@media(max-width:600px){.hero-ico{display:none}.hero{padding:22px 20px}.hero-text h2{font-size:20px}}

/* ---------- cards & stat tiles ---------- */
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);overflow:hidden}
.card-head{display:flex;align-items:center;justify-content:space-between;padding:17px 20px;border-bottom:1px solid var(--border)}
.card-head h3{margin:0;font-size:15px;font-weight:600}
.card-body{padding:20px}
.grid{display:grid;gap:18px}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-4{grid-template-columns:repeat(4,1fr)}
@media(max-width:1100px){.grid-4{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(2,1fr)}}
@media(max-width:680px){.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}}

.stat{position:relative;background:var(--surface);border:1px solid var(--border);border-top:3px solid var(--brand);border-radius:var(--radius-lg);padding:18px 20px;box-shadow:var(--shadow);display:flex;flex-direction:column;gap:6px;transition:transform .16s,box-shadow .16s}
.stat:hover{transform:translateY(-3px);box-shadow:var(--shadow-md)}
.stat-top{display:flex;align-items:flex-start;justify-content:space-between;gap:10px}
.stat .lbl{font-size:12.5px;color:var(--muted);font-weight:600;display:flex;align-items:center;gap:8px;letter-spacing:.2px}
.stat .ico{width:40px;height:40px;border-radius:12px;display:flex;align-items:center;justify-content:center;font-size:17px;flex-shrink:0}
.stat .val{font-size:28px;font-weight:700;letter-spacing:-.8px;line-height:1.1;margin-top:2px}
.stat .sub{font-size:12px;color:var(--faint);font-weight:500}
.stat.accent-green{border-top-color:var(--brand)}
.stat.accent-blue{border-top-color:var(--blue)}
.stat.accent-violet{border-top-color:var(--violet)}
.stat.accent-amber{border-top-color:var(--amber)}
.stat.accent-red{border-top-color:var(--red)}
.ico-green{background:var(--brand-soft);color:var(--brand-dark)}
.ico-blue{background:var(--blue-soft);color:var(--blue)}
.ico-violet{background:var(--violet-soft);color:var(--violet)}
.ico-amber{background:var(--amber-soft);color:var(--amber)}
.ico-red{background:var(--red-soft);color:var(--red)}

/* ---------- tables ---------- */
.table-wrap{overflow-x:auto}
table.tbl{width:100%;border-collapse:collapse;font-size:13.5px}
table.tbl th{text-align:left;padding:12px 16px;background:var(--surface-2);color:var(--muted);font-weight:600;font-size:11.5px;text-transform:uppercase;letter-spacing:.6px;border-bottom:1px solid var(--border);white-space:nowrap}
table.tbl td{padding:14px 16px;border-bottom:1px solid var(--border);vertical-align:middle}
table.tbl tr:last-child td{border-bottom:none}
table.tbl tbody tr{transition:background .12s}
table.tbl tbody tr:hover{background:var(--surface-2)}

/* ---------- badges ---------- */
.badge{display:inline-flex;align-items:center;gap:5px;padding:4px 11px;border-radius:20px;font-size:11.5px;font-weight:600;line-height:1.5}
.badge-green{background:var(--brand-soft);color:var(--brand-dark)}
.badge-blue{background:var(--blue-soft);color:#0369a1}
.badge-amber{background:var(--amber-soft);color:#b45309}
.badge-red{background:var(--red-soft);color:#b91c1c}
.badge-gray{background:#f1f5f9;color:#475569}
.badge-violet{background:var(--violet-soft);color:#6d28d9}

/* ---------- buttons ---------- */
.btn{display:inline-flex;align-items:center;gap:7px;padding:10px 16px;border-radius:10px;border:1px solid var(--border-strong);background:var(--surface);color:var(--text);font-size:13.5px;font-weight:600;transition:background .15s,border-color .15s,transform .12s,box-shadow .15s}
.btn:hover{background:var(--surface-2)}
.btn:active{transform:translateY(1px)}
.btn-primary{background:var(--brand);border-color:var(--brand);color:#fff;box-shadow:0 4px 12px rgba(22,163,74,.24)}
.btn-primary:hover{background:var(--brand-dark);border-color:var(--brand-dark)}
.btn-blue{background:var(--blue);border-color:var(--blue);color:#fff;box-shadow:0 4px 12px rgba(14,165,233,.24)}
.btn-blue:hover{filter:brightness(.96)}
.btn-danger{background:var(--red);border-color:var(--red);color:#fff;box-shadow:0 4px 12px rgba(220,38,38,.24)}
.btn-danger:hover{filter:brightness(.96)}
.btn-ghost{border-color:transparent;background:transparent;color:var(--muted);box-shadow:none}
.btn-ghost:hover{background:var(--surface-2);color:var(--text)}
.btn-sm{padding:6px 12px;font-size:12.5px}
.btn-icon{padding:8px 10px}
.btn:disabled{opacity:.55;cursor:not-allowed;transform:none;box-shadow:none}

/* ---------- forms ---------- */
.field{margin-bottom:15px}
.field label{display:block;font-size:12.5px;font-weight:600;color:var(--muted);margin-bottom:6px}
.field .req{color:var(--red)}
.input,select.input,textarea.input{width:100%;padding:11px 13px;border:1px solid var(--border-strong);border-radius:10px;background:var(--surface);color:var(--text);transition:border .15s,box-shadow .15s}
.input::placeholder,textarea.input::placeholder{color:#aab4c0}
.input:focus,select.input:focus,textarea.input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(22,163,74,.13)}
textarea.input{resize:vertical;min-height:84px}
.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:0 16px}
@media(max-width:680px){.form-grid{grid-template-columns:1fr}}
.form-actions{display:flex;gap:10px;justify-content:flex-end;margin-top:8px}

/* ---------- toolbar ---------- */
.toolbar{display:flex;align-items:center;gap:12px;margin-bottom:20px;flex-wrap:wrap}
.toolbar .search{flex:1;min-width:200px;position:relative}
.toolbar .search i{position:absolute;left:14px;top:50%;transform:translateY(-50%);color:var(--faint);font-size:14px}
.toolbar .search input{width:100%;padding:11px 13px 11px 40px;border:1px solid var(--border-strong);border-radius:10px;background:var(--surface);transition:border .15s,box-shadow .15s}
.toolbar .search input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(22,163,74,.13)}
.spacer{flex:1}

/* ---------- modal ---------- */
.modal-bg{position:fixed;inset:0;z-index:100;background:rgba(15,23,42,.55);backdrop-filter:blur(5px);display:flex;align-items:flex-start;justify-content:center;padding:40px 16px;opacity:0;visibility:hidden;transition:opacity .2s,visibility .2s;overflow-y:auto}
.modal-bg.open{opacity:1;visibility:visible}
.modal{width:min(640px,100%);background:var(--surface);border-radius:18px;box-shadow:var(--shadow-lg);transform:translateY(16px) scale(.98);transition:transform .24s cubic-bezier(.2,.8,.2,1)}
.modal-bg.open .modal{transform:translateY(0) scale(1)}
.modal-head{display:flex;align-items:center;justify-content:space-between;padding:18px 22px;border-bottom:1px solid var(--border)}
.modal-head h3{margin:0;font-size:16px;font-weight:600}
.modal-close{width:34px;height:34px;border:none;background:var(--surface-2);border-radius:50%;font-size:18px;color:var(--muted);transition:background .15s,color .15s}
.modal-close:hover{background:#e2e8f0;color:var(--text)}
.modal-body{padding:22px;max-height:70vh;overflow-y:auto}
.modal-foot{display:flex;gap:10px;justify-content:flex-end;padding:16px 22px;border-top:1px solid var(--border)}

/* ---------- toast ---------- */
#toastWrap{position:fixed;bottom:24px;right:24px;z-index:200;display:flex;flex-direction:column;gap:10px}
.toast{min-width:240px;max-width:360px;padding:14px 17px;border-radius:13px;background:#0f172a;color:#fff;font-size:13.5px;box-shadow:var(--shadow-lg);opacity:0;transform:translateX(20px);transition:all .3s;border-left:4px solid var(--brand)}
.toast.show{opacity:1;transform:translateX(0)}
.toast-success{border-left-color:var(--brand)}
.toast-error{border-left-color:var(--red)}
.toast-info{border-left-color:var(--blue)}

/* ---------- misc ---------- */
.empty{text-align:center;padding:52px 20px;color:var(--faint)}
.empty i{font-size:40px;margin-bottom:14px;display:block;opacity:.45}
.loading{text-align:center;padding:44px;color:var(--muted)}
.spinner{width:32px;height:32px;border:3px solid var(--border);border-top-color:var(--brand);border-radius:50%;animation:spin .7s linear infinite;margin:0 auto 12px}
@keyframes spin{to{transform:rotate(360deg)}}
.page-title{font-size:21px;font-weight:700;margin:0 0 4px;letter-spacing:-.3px}
.page-sub{color:var(--muted);font-size:13.5px;margin:0 0 22px}
.row{display:flex;align-items:center;gap:10px}
.muted{color:var(--muted)} .faint{color:var(--faint)}
.mt0{margin-top:0}.mb0{margin-bottom:0}

/* ---------- mobile ---------- */
.sidebar-backdrop{display:none;position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:39}
@media(max-width:920px){
  .sidebar{transform:translateX(-100%);box-shadow:var(--shadow-lg)}
  .sidebar.open{transform:translateX(0)}
  .sidebar-backdrop.open{display:block}
  .main{margin-left:0}
  .hamburger{display:flex}
  .user-mini .nm,.user-mini .rl{display:none}
  .content{padding:18px}
}