* {
  box-sizing: border-box;
}

:root {
  --bg: #eef2f7;
  --panel: #ffffff;
  --ink: #1b2638;
  --muted: #6c7a90;
  --accent: #0f5ea9;
  --accent-dark: #0b4a83;
  --line: #d8e1ee;
  --chip: #f1f5fb;
  --shadow: 0 18px 40px rgba(15, 40, 80, 0.08);
}

body {
  margin: 0;
  font-family: "Trebuchet MS", "Lucida Sans Unicode", "Candara", sans-serif;
  background: radial-gradient(circle at top left, #f6f9ff, #e8eef7 55%, #dce7f3 100%);
  color: var(--ink);
}

.app::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(600px 300px at 80% 10%, rgba(255, 255, 255, 0.6), transparent 60%),
    radial-gradient(500px 260px at 20% 20%, rgba(255, 255, 255, 0.45), transparent 60%),
    linear-gradient(135deg, rgba(11, 42, 74, 0.06), rgba(15, 94, 169, 0.08));
}

.app::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='800' height='300' viewBox='0 0 800 300' fill='none'><path d='M40 160c60-10 120-18 180-22 60-4 120-5 180-3 60 2 120 8 180 18' stroke='%23c7d6ea' stroke-width='2' stroke-linecap='round'/><path d='M540 70l40 10-15 5-25-15z' fill='%23c7d6ea'/><path d='M545 72l20 20-12 4-8-24z' fill='%23c7d6ea'/></svg>") no-repeat 85% 10%,
    url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='600' height='220' viewBox='0 0 600 220' fill='none'><path d='M20 120c50-12 100-20 150-25 55-6 110-8 165-7 55 1 110 6 165 16' stroke='%23d2dfef' stroke-width='2' stroke-linecap='round'/><path d='M360 40l28 8-10 4-18-12z' fill='%23d2dfef'/><path d='M365 42l14 14-8 3-6-17z' fill='%23d2dfef'/></svg>") no-repeat 10% 22%;
  opacity: 0.7;
}

.login-root {
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: linear-gradient(160deg, #0b2a4a, #14365f 50%, #1d3f6b);
}

.login-card {
  background: #ffffff;
  padding: 28px;
  border-radius: 16px;
  width: 320px;
  display: grid;
  gap: 12px;
  box-shadow: var(--shadow);
}

.brand-mark {
  width: 110px;
  height: 110px;
  margin: 0 auto 4px;
  border-radius: 14px;
  overflow: hidden;
  border: 1px solid #d6e1ee;
  background: #ffffff;
}

.login-card h1 {
  margin: 0;
  font-size: 22px;
  text-align: center;
}

.login-card p {
  margin: 0 0 6px;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

.login-error {
  color: #b42318;
  font-size: 12px;
}

.app {
  min-height: 100vh;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 240px;
  height: 100vh;
  background: linear-gradient(180deg, #0b2a4a, #102d52 55%, #0f2440);
  color: #e8f1ff;
  padding: 24px 18px;
  display: flex;
  flex-direction: column;
  gap: 24px;
  overflow-y: auto;
  overflow-x: hidden;
  z-index: 2;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-wrap {
  width: 54px;
  height: 54px;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: #0f2f54;
}

.logo-img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
}

.brand-title {
  font-weight: 700;
  font-size: 16px;
}

.brand-sub {
  font-size: 12px;
  opacity: 0.7;
}

.nav {
  display: grid;
  gap: 10px;
}

.nav-item {
  background: transparent;
  color: inherit;
  border: 1px solid rgba(255, 255, 255, 0.12);
  padding: 10px 12px;
  border-radius: 12px;
  text-align: left;
  cursor: pointer;
}

.nav-item.active,
.nav-item:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.3);
}

.side-card {
  margin-top: auto;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 16px;
  padding: 14px;
}

.side-card-title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 10px;
  opacity: 0.7;
}

.side-card-row {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
}

.main {
  margin-left: 240px;
  padding: 28px 32px 40px;
  display: grid;
  gap: 20px;
  animation: fadeIn 0.6s ease;
  position: relative;
  z-index: 1;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.topbar h1 {
  margin: 0;
  font-size: 26px;
}

.topbar p {
  margin: 6px 0 0;
  color: var(--muted);
}

.top-actions {
  display: flex;
  gap: 12px;
  align-items: center;
}

.search {
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  min-width: 220px;
  background: #fff;
}

.grid {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 20px;
}

.panel {
  background: var(--panel);
  border-radius: 18px;
  box-shadow: var(--shadow);
  padding: 18px;
  border: 1px solid var(--line);
  backdrop-filter: blur(2px);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 12px;
}

.panel-header h2 {
  margin: 0;
  font-size: 18px;
}

.hint {
  font-size: 12px;
  color: var(--muted);
}

.student-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 10px;
  max-height: 460px;
  overflow: auto;
}

.student-item {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
  display: grid;
  gap: 4px;
  cursor: pointer;
  background: #fff;
}

.student-item:hover,
.student-item.active {
  border-color: var(--accent);
  box-shadow: 0 8px 16px rgba(15, 94, 169, 0.15);
}

.student-meta {
  font-size: 12px;
  color: var(--muted);
}

.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 14px;
}

.metric {
  background: var(--chip);
  padding: 12px;
  border-radius: 14px;
}

.metric-label {
  font-size: 12px;
  color: var(--muted);
}

.metric-value {
  font-size: 20px;
  font-weight: 700;
  margin-top: 6px;
}

.tabs {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
}

.tab {
  border: 1px solid var(--line);
  background: #fff;
  padding: 8px 14px;
  border-radius: 10px;
  cursor: pointer;
}

.tab.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.tab-content table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  text-align: left;
  padding: 10px 6px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}

.empty {
  color: var(--muted);
  text-align: center;
  padding: 20px 0;
}

.meta {
  color: var(--muted);
  font-size: 13px;
}

.form-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.attendance-form {
  grid-template-columns: 220px 180px 180px;
  align-items: center;
}

.attendance-meta {
  display: flex;
  gap: 18px;
  margin: 10px 0 6px;
  color: var(--muted);
  font-size: 13px;
}

.attendance-hero {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 20px;
  align-items: center;
}

.attendance-percent {
  background: radial-gradient(circle at 30% 20%, #ffffff, #e5eefb 60%, #d5e4f8 100%);
  border-radius: 20px;
  padding: 18px;
  border: 1px solid #d7e4f4;
  box-shadow: 0 16px 30px rgba(9, 44, 88, 0.12);
}

.attendance-percent-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: #5b6c86;
}

.attendance-percent-value {
  font-size: 48px;
  font-weight: 800;
  color: #0b4a83;
  margin-top: 6px;
}

.attendance-list table {
  width: 100%;
  border-collapse: collapse;
}

input {
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
}

.btn {
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: #fff;
  cursor: pointer;
}

.btn.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.btn.primary:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
}

.logout-btn {
  margin-top: 0;
  background: transparent;
  color: #e8f1ff;
  border-color: rgba(255, 255, 255, 0.2);
}

.logout-btn:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.35);
}

.section {
  display: grid;
  gap: 20px;
}

.hidden {
  display: none;
}

.section.hidden {
  display: none;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 1100px) {
  .sidebar {
    width: 200px;
  }

  .main {
    margin-left: 200px;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  .form-row {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 820px) {
  .sidebar {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    top: auto;
    height: 80px;
    width: 100%;
    padding: 8px 10px;
    flex-direction: row;
    align-items: stretch;
    justify-content: flex-start;
    gap: 8px;
    border-top: 1px solid rgba(255, 255, 255, 0.15);
    overflow: hidden;
  }

  .brand,
  .side-card {
    display: none;
  }

  .nav {
    display: flex;
    gap: 8px;
    overflow-x: auto;
    overflow-y: hidden;
    padding-bottom: 4px;
    scrollbar-width: thin;
    flex: 1;
  }

  .nav-item {
    white-space: nowrap;
    padding: 10px 12px;
    min-width: max-content;
  }

  .logout-btn {
    margin: 0;
    white-space: nowrap;
    padding: 10px 12px;
    align-self: center;
  }

  .main {
    margin-left: 0;
    padding: 18px 14px 110px;
  }

  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .top-actions {
    width: 100%;
    overflow-x: auto;
  }

  .search {
    min-width: 0;
    width: 100%;
  }

  .metrics {
    grid-template-columns: 1fr 1fr;
  }

  .attendance-hero {
    grid-template-columns: 1fr;
  }

  .attendance-percent-value {
    font-size: 40px;
  }

  th,
  td {
    font-size: 12px;
    padding: 8px 4px;
  }
}