:root{
  --green:#19a84a;
  --black:#111;
  --light:#f5f7f5;
  --muted:#67706b;
  --border:#dfe6df;
  --danger:#b42318;
}
*{box-sizing:border-box}
body{
  margin:0;
  font-family:Arial, Helvetica, sans-serif;
  background:var(--light);
  color:var(--black);
}
.topbar{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:24px;
  padding:28px;
  background:#111;
  color:white;
}
.eyebrow{
  margin:0 0 6px;
  color:var(--green);
  font-weight:800;
  letter-spacing:.08em;
  text-transform:uppercase;
  font-size:12px;
}
h1,h2,h3{margin:0}
h1{font-size:36px}
.subtitle{margin:8px 0 0;color:#d6d6d6}
.actions,.date-row,.student-form,.modal-actions{
  display:flex;
  gap:10px;
  flex-wrap:wrap;
}
.layout{
  padding:24px;
  display:grid;
  gap:20px;
}
.card{
  background:white;
  border:1px solid var(--border);
  border-radius:22px;
  padding:22px;
  box-shadow:0 10px 30px rgba(0,0,0,.05);
}
.grid{
  display:grid;
  grid-template-columns:repeat(4, minmax(180px,1fr));
  gap:14px;
  margin-top:16px;
}
label{
  display:flex;
  flex-direction:column;
  gap:6px;
  font-weight:700;
  color:#263029;
}
input{
  border:1px solid var(--border);
  border-radius:12px;
  padding:12px 13px;
  font-size:15px;
}
.btn{
  border:0;
  border-radius:12px;
  padding:12px 16px;
  background:var(--green);
  color:white;
  font-weight:800;
  cursor:pointer;
}
.btn.secondary{
  background:white;
  color:#111;
  border:1px solid var(--border);
}
.btn.danger{background:var(--danger)}
.icon-btn{
  border:0;
  background:#f2f2f2;
  border-radius:999px;
  width:38px;
  height:38px;
  font-size:24px;
  cursor:pointer;
}
.chips{
  display:flex;
  gap:8px;
  flex-wrap:wrap;
  margin-top:12px;
}
.chip{
  display:inline-flex;
  align-items:center;
  gap:8px;
  background:#ecf8ef;
  color:#0f6a2e;
  border:1px solid #bce8c8;
  padding:8px 10px;
  border-radius:999px;
  font-weight:700;
}
.chip button{
  border:0;
  background:transparent;
  color:#0f6a2e;
  cursor:pointer;
  font-weight:900;
}
.student-form{
  margin-top:15px;
}
.student-form input{flex:1;min-width:220px}
.sheet-header{
  display:flex;
  justify-content:space-between;
  gap:20px;
  border-bottom:3px solid var(--green);
  padding-bottom:16px;
  margin-bottom:18px;
}
.brand{
  margin:0 0 6px;
  font-weight:900;
  color:var(--green);
}
#courseMeta{color:var(--muted);margin:8px 0 0}
.stamp{
  border:1px solid var(--border);
  border-radius:16px;
  padding:12px 16px;
  min-width:170px;
  text-align:center;
}
.stamp span{
  display:block;
  font-size:12px;
  color:var(--muted);
  margin-bottom:5px;
}
.table-wrap{overflow:auto}
table{
  width:100%;
  border-collapse:collapse;
  min-width:780px;
}
th,td{
  border:1px solid var(--border);
  padding:10px;
  text-align:left;
  vertical-align:middle;
}
th{
  background:#111;
  color:white;
  font-size:13px;
}
td.small, th.small{width:55px;text-align:center}
.presence-cell{
  min-width:165px;
}
.presence-tools{
  display:grid;
  gap:7px;
}
.checkline{
  display:flex;
  gap:8px;
  align-items:center;
  font-size:13px;
}
.sign-preview{
  height:42px;
  border:1px dashed #aeb7af;
  border-radius:8px;
  background:#fff;
  display:flex;
  align-items:center;
  justify-content:center;
  overflow:hidden;
  color:#8a928c;
  font-size:12px;
}
.sign-preview img{
  width:100%;
  height:100%;
  object-fit:contain;
}
.sign-btn{
  border:1px solid var(--green);
  background:#f1fff5;
  color:#0f6a2e;
  border-radius:8px;
  padding:7px 8px;
  font-weight:800;
  cursor:pointer;
}
.row-btn{
  border:0;
  background:#fff2f2;
  color:var(--danger);
  border-radius:8px;
  padding:7px;
  cursor:pointer;
}
.footer-note{
  display:flex;
  justify-content:space-between;
  gap:18px;
  color:#4b554f;
  margin-top:18px;
  font-size:13px;
}
.modal{
  position:fixed;
  inset:0;
  background:rgba(0,0,0,.55);
  display:flex;
  align-items:center;
  justify-content:center;
  padding:20px;
  z-index:50;
}
.modal.hidden{display:none}
.modal-box{
  background:white;
  width:min(820px,100%);
  border-radius:22px;
  padding:20px;
}
.modal-header{
  display:flex;
  justify-content:space-between;
  align-items:center;
  margin-bottom:14px;
}
canvas{
  width:100%;
  height:260px;
  border:2px dashed #aab3ad;
  border-radius:16px;
  background:white;
  touch-action:none;
}
@media(max-width:900px){
  .topbar,.sheet-header,.footer-note{flex-direction:column}
  .grid{grid-template-columns:1fr}
}
@media print{
  body{background:white}
  .topbar,.setup,.sign-btn,.row-btn,.modal{display:none !important}
  .layout{padding:0}
  .card{box-shadow:none;border:0;border-radius:0}
  th{background:#111 !important;color:white !important;-webkit-print-color-adjust:exact;print-color-adjust:exact}
  .sign-preview{border:0}
  input[type="checkbox"]{transform:scale(1.2)}
}


.login-screen{
  position:fixed;
  inset:0;
  background:linear-gradient(135deg, #101010, #1b1f1c);
  display:flex;
  align-items:center;
  justify-content:center;
  padding:22px;
  z-index:999;
}
.login-screen.hidden{
  display:none;
}
.login-card{
  width:min(430px, 100%);
  background:white;
  border-radius:26px;
  padding:32px;
  box-shadow:0 30px 80px rgba(0,0,0,.35);
}
.login-card h1{
  color:#111;
  font-size:32px;
}
.login-text{
  color:var(--muted);
  line-height:1.45;
}
.login-card input{
  width:100%;
  margin:12px 0;
}
.login-card .btn{
  width:100%;
}
.login-error{
  min-height:20px;
  color:var(--danger);
  font-weight:700;
  margin:12px 0 0;
}
body.locked{
  overflow:hidden;
}
@media print{
  .login-screen, #logoutBtn{display:none !important}
}