@import url('https://fonts.googleapis.com/css2?family=DM+Serif+Display&family=DM+Sans:wght@400;500;600;700&family=DM+Mono:wght@400;500&display=swap');

:root{
  --ink:#1B1E33;--ink2:#42456B;--ink3:#71749B;
  --paper:#F6F7FC;--surface:#EDEEF8;--border:#DEE1F2;
  --teal:#5B5FEF;--teal-lt:#ECEBFE;--teal-dk:#4245C9;
  --rose:#EF4477;--rose-lt:#FDE8F0;
  --amber:#D97706;--amber-lt:#FEF3C7;
  --purple:#8B5CF6;--purple-lt:#F1EBFF;
  --blue:#3B82F6;--blue-lt:#EAF1FF;
  --shadow:0 1px 4px rgba(27,30,51,.08),0 4px 16px rgba(27,30,51,.06);
  --r:12px;--r-sm:8px;--r-lg:20px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scrollbar-color:var(--ink3) transparent}
::selection{background:var(--teal);color:#fff}
::-webkit-scrollbar{width:10px;height:10px}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:20px}
::-webkit-scrollbar-thumb:hover{background:var(--ink3)}
body{
  font-family:'DM Sans',system-ui,sans-serif;color:var(--ink);font-size:15px;line-height:1.6;
  background:
    radial-gradient(1100px 480px at 12% -8%, rgba(91,95,239,.09), transparent 60%),
    radial-gradient(900px 420px at 100% 0%, rgba(139,92,246,.07), transparent 55%),
    var(--paper);
  background-attachment:fixed;
  min-height:100vh;
}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}
h1,h2,h3{font-family:'DM Serif Display',serif;font-weight:400}
a{color:var(--teal)}
code{font-family:'DM Mono',monospace;background:var(--surface);padding:1px 6px;border-radius:5px;font-size:.9em}

.btn{font-family:'DM Sans';font-weight:600;border:none;border-radius:var(--r-sm);cursor:pointer;transition:transform .12s ease,box-shadow .12s ease,background .15s,border-color .15s,color .15s;display:inline-flex;align-items:center;gap:6px;text-decoration:none}
.btn-sm{font-size:12px;padding:6px 12px}
.btn-md{font-size:14px;padding:10px 20px}
.btn-lg{font-size:16px;padding:14px 28px}
.btn-teal{background:linear-gradient(180deg,#6A6EF5,var(--teal));color:#fff;box-shadow:0 1px 2px rgba(66,69,201,.25),0 6px 16px rgba(91,95,239,.28)}
.btn-teal:hover{background:linear-gradient(180deg,#6A6EF5,var(--teal-dk));box-shadow:0 1px 2px rgba(66,69,201,.3),0 8px 20px rgba(91,95,239,.36);transform:translateY(-1px)}
.btn-teal:active{transform:translateY(0);box-shadow:0 1px 2px rgba(66,69,201,.25)}
.btn-outline{background:#fff;color:var(--ink);border:1.5px solid var(--border)}.btn-outline:hover{border-color:var(--teal);color:var(--teal-dk);box-shadow:0 2px 8px rgba(27,30,51,.06)}
.btn-ghost{background:transparent;color:var(--ink3);border:none}.btn-ghost:hover{color:var(--ink);background:var(--surface)}
.btn-rose{background:linear-gradient(180deg,#F25C8B,var(--rose));color:#fff;box-shadow:0 6px 16px rgba(239,68,119,.28)}.btn-rose:hover{filter:brightness(.94)}
.btn:disabled{opacity:.5;cursor:not-allowed;box-shadow:none;transform:none}

.panel{background:#fff;border:1px solid var(--border);border-radius:var(--r-lg);padding:24px;margin-bottom:16px;box-shadow:var(--shadow)}
.panel-title{font-size:22px;margin-bottom:4px;display:flex;align-items:center;gap:10px}
.panel-title .picon{width:34px;height:34px;border-radius:10px;background:var(--teal-lt);color:var(--teal-dk);display:inline-flex;align-items:center;justify-content:center;font-size:16px;flex-shrink:0}
.panel-sub{font-size:13px;color:var(--ink3);margin-bottom:18px}

/* top nav, shared across app pages */
.topnav{position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:12px;padding:14px 24px;
  background:rgba(255,255,255,.82);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);
  border-bottom:1px solid var(--border);box-shadow:0 1px 0 rgba(27,30,51,.02)}
.topnav .brand{font-family:'DM Serif Display',serif;font-size:18px;color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:8px}
.topnav .brand em{font-style:italic;color:var(--teal)}
.topnav .sp{flex:1}
.topnav .avatar{width:28px;height:28px;border-radius:50%;background:linear-gradient(135deg,var(--teal),var(--purple));color:#fff;font-size:12px;font-weight:700;display:inline-flex;align-items:center;justify-content:center}

/* data tables */
.dtable{width:100%;border-collapse:separate;border-spacing:0;font-size:13px}
.dtable thead th{position:sticky;top:0;background:var(--surface);color:var(--ink3);text-align:left;font-size:10.5px;font-weight:700;text-transform:uppercase;letter-spacing:.4px;padding:10px 12px;border-bottom:1px solid var(--border)}
.dtable tbody td{padding:10px 12px;border-bottom:1px solid var(--border);vertical-align:middle}
.dtable tbody tr:last-child td{border-bottom:none}
.dtable tbody tr:hover td{background:var(--surface)}
.dtable-wrap{border:1px solid var(--border);border-radius:var(--r);overflow:hidden}

.empty{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;padding:28px 16px;color:var(--ink3);text-align:center}
.empty .eicon{font-size:26px;opacity:.6}
.empty .etext{font-size:13px}

.fld{display:flex;flex-direction:column;gap:4px;margin-bottom:12px}
.fld label{font-size:11px;font-weight:700;color:var(--ink2);letter-spacing:.4px;text-transform:uppercase}
.fld input,.fld select,.fld textarea{padding:9px 11px;border-radius:var(--r-sm);border:1.5px solid var(--border);font-family:'DM Sans';font-size:14px;background:#fff;color:var(--ink)}
.fld input:focus,.fld select:focus,.fld textarea:focus{outline:none;border-color:var(--teal);box-shadow:0 0 0 3px var(--teal-lt)}

.msg-err{background:var(--rose-lt);color:#9B1B3B;border-radius:var(--r-sm);padding:10px 14px;font-weight:600;font-size:13px;margin-top:10px}
.msg-ok{background:var(--teal-lt);color:var(--teal-dk);border-radius:var(--r-sm);padding:10px 14px;font-weight:600;font-size:13px;margin-top:10px}

.pill{display:inline-flex;font-size:11px;font-weight:700;border-radius:20px;padding:3px 10px}
.badge{font-size:10px;font-weight:700;border-radius:6px;padding:2px 7px}

.toast-stack{position:fixed;top:16px;right:16px;z-index:400;display:flex;flex-direction:column;gap:8px;max-width:320px}
.toast{background:var(--ink);color:#fff;padding:10px 14px;border-radius:var(--r-sm);font-size:13px;font-weight:600;box-shadow:var(--shadow);animation:slidein .2s ease-out}
.toast.stuck{background:var(--rose)}
@keyframes slidein{from{transform:translateX(20px);opacity:0}to{transform:translateX(0);opacity:1}}

/* status colors, shared across teacher grid + student buttons */
.st-not_started{background:var(--surface);color:var(--ink3);border-color:var(--border)}
.st-in_progress{background:var(--blue-lt);color:var(--blue);border-color:var(--blue)}
.st-done{background:var(--teal-lt);color:var(--teal-dk);border-color:var(--teal)}
.st-stuck{background:var(--rose-lt);color:var(--rose);border-color:var(--rose)}

@keyframes celebrate{
  0%{transform:scale(1)}
  30%{transform:scale(1.12)}
  55%{transform:scale(.97)}
  100%{transform:scale(1)}
}
.celebrating{animation:celebrate .6s ease-in-out;box-shadow:0 0 0 3px var(--amber)!important}