@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600;700&display=swap');

:root {
  /* Palette: Modern & Dynamic */
  --bg-color: #f4f7fc; /* Soft, light blue-gray background */
  --surface-color: #ffffff;
  --primary-color: #4a69e2; /* Vibrant blue for primary actions */
  --primary-hover: #3b55b5;
  --secondary-color: #1e293b; /* Deep slate for text and headers */
  --accent-color: #f59e0b; /* Warm amber for accents */
  --border-color: #e2e8f0;
  --text-color: #334155;
  --muted-color: #64748b;

  /* Typography */
  --font-body: 'Poppins', sans-serif;
  --font-heading: 'Poppins', sans-serif;

  /* Layout */
  --max-width: 1200px;
  --radius-sm: 0.375rem;
  --radius-md: 0.75rem;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Base & Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.7;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

main {
  flex-grow: 1;
  padding: 2rem 1rem;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--secondary-color);
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 1rem;
}

a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition);
}

a:hover {
  color: var(--primary-hover);
}

/* Header */
.hero {
  background-color: var(--surface-color);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

.hero-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 2rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.logo {
  display: grid;
  place-items: center;
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: linear-gradient(45deg, var(--primary-color), #6a82ff);
  color: white;
  font-size: 1.6rem;
  font-weight: 700;
  font-family: var(--font-body);
  box-shadow: 0 4px 12px rgba(74, 105, 226, 0.3);
  transition: transform var(--transition);
}

.brand:hover .logo {
  transform: translateY(-2px) scale(1.05);
}

.titles h1 {
  font-size: 1.25rem;
  margin: 0;
  font-family: var(--font-heading);
  font-weight: 600;
}

.titles p {
  margin: 0;
  color: var(--muted-color);
  font-size: 0.9rem;
}

/* Navigation Tabs */
.header-actions {
  justify-self: end;
}

.tabs {
  display: flex;
  gap: 0.25rem;
  list-style: none;
  margin-top: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.tab {
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--muted-color);
  background-color: transparent;
  border: 1px solid transparent;
  white-space: nowrap;
  transition: all var(--transition);
  cursor: pointer;
}

.tab:hover {
  color: var(--secondary-color);
  background-color: #eef2ff;
  text-decoration: none;
}

.tab.active {
  color: white;
  background-color: var(--primary-color);
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(74, 105, 226, 0.2);
}

/* Main Content & Panels */
.panel {
  display: none;
}

.panel.active {
  display: block;
  animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Reduce flashing/jitter on Homework panel */
#homework.panel.active {
  animation: none;
}

/* Cards */
.card {
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-md);
  transition: all var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

/* Forms & Buttons */
.selector {
  padding: 2rem;
  align-items: center;
}

#student-select {
  min-width: 250px;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background-color: var(--surface-color);
  font-size: 1rem;
  font-weight: 500;
  transition: all var(--transition);
}

#student-select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(74, 105, 226, 0.15);
}

#copy-link {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: var(--radius-sm);
  background: linear-gradient(45deg, var(--primary-color), #6a82ff);
  color: white;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: var(--shadow-md);
}

#copy-link:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* Tables */
.table-container {
  overflow-x: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background-color: var(--surface-color);
  box-shadow: var(--shadow-sm);
}

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

.table th, .table td {
  padding: 1rem 1.5rem;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.table th {
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--muted-color);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.table tbody tr:last-child th,
.table tbody tr:last-child td {
  border-bottom: 0;
}

.table tbody tr:hover {
  background-color: var(--bg-color);
}

/* Accordion for Homework & Notes */
.accordion {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.accordion details {
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.accordion details[open] {
  box-shadow: var(--shadow-lg);
}

.accordion summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.25rem 1.5rem;
  cursor: pointer;
  list-style: none; /* Remove default marker */
  font-weight: 600;
  color: var(--secondary-color);
}

.accordion summary::-webkit-details-marker {
  display: none; /* Chrome, Safari */
}

.accordion summary::after {
  content: '+';
  font-size: 1.5rem;
  font-weight: 400;
  color: var(--primary-color);
  transition: transform var(--transition);
}

.accordion details[open] summary::after {
  transform: rotate(45deg);
}

.hw-content {
  padding: 0 1.5rem 1.5rem;
  border-top: 1px solid var(--border-color);
}

.hw-iframe-container {
  position: relative;
  min-height: 300px;
}

.iframe-placeholder {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 300px;
  background-color: var(--bg-color);
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color var(--transition);
}

.iframe-placeholder:hover {
  background-color: #eef2ff;
}

.iframe-placeholder .load-btn {
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.iframe-placeholder .load-btn svg {
  width: 20px;
  height: 20px;
}

.progress-bar-container {
  width: 80%;
  max-width: 400px;
  background-color: var(--border-color);
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar {
  width: 0%;
  height: 10px;
  background-color: var(--primary-color);
  border-radius: 999px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.progress-text {
  margin-top: 0.5rem;
  font-weight: 500;
  color: var(--muted-color);
}

/* Footer */
.site-footer {
  margin-top: auto; /* push to bottom when content is short */
  border-top: 1px solid var(--border-color);
  background-color: var(--surface-color);
  color: var(--muted-color);
}

.site-footer .footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  padding: 1.2rem 1rem;
}

.site-footer .footer-title {
  margin: 0 0 .4rem 0;
  font-size: 1rem;
  color: var(--secondary-color);
}

.site-footer .footer-list {
  list-style: none;
  margin: 0;
  padding: 0;
  color: var(--muted-color);
  font-size: .95rem;
}

.site-footer .footer-list li { margin: .25rem 0; }

.site-footer .footer-bottom {
  border-top: 1px solid var(--border-color);
  background: var(--surface-color);
}

.site-footer .footer-bottom small {
  display: block;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: .8rem 1rem;
  color: var(--muted-color);
}

@media (max-width: 768px) {
  .site-footer .footer-inner {
    grid-template-columns: 1fr;
  }
}

/* Center loading indicator for homework iframes */
.loading-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  min-height: 200px;
}

.loading-spinner {
  width: 48px;
  height: 48px;
  border: 5px solid var(--border-color);
  border-bottom-color: var(--primary-color);
  border-radius: 50%;
  display: inline-block;
  box-sizing: border-box;
  animation: rotation 1s linear infinite;
}

@keyframes rotation {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

.hw-iframe-container iframe {
  width: 100%;
  height: 80vh;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background-color: white;
}



/* ========================= */
/* Responsive enhancements   */
/* ========================= */

/* Utility text classes */
.muted { color: var(--muted-color); }
.small { font-size: 0.9rem; }

/* Layout helpers */
.grid { display: grid; gap: 1.25rem; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.row-wrap { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; }

/* Key-value tables */
.kv { width: 100%; border-collapse: collapse; }
.kv th, .kv td { padding: .5rem .75rem; border-bottom: 1px solid var(--border-color); text-align: left; }
.kv th { width: 38%; color: var(--muted-color); font-weight: 600; }
.kv tr:last-child th, .kv tr:last-child td { border-bottom: 0; }

/* Portal (Results) */
.portal-card { background: var(--surface-color); }
.portal-inner { display: flex; flex-direction: column; gap: .75rem; }
.portal-title { margin: 0; }
.portal-sub { color: var(--muted-color); margin-top: -.4rem; }
.portal-fields { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: .75rem; margin-top: .5rem; }
.portal-input { padding: .7rem .9rem; border: 1px solid var(--border-color); border-radius: var(--radius-sm); font-size: 1rem; }
.portal-or { color: var(--muted-color); }
.portal-actions { margin-top: .5rem; }
.portal-btn { padding: .7rem 1.25rem; border: none; border-radius: var(--radius-sm); background: var(--primary-color); color: #fff; font-weight: 600; cursor: pointer; }
.portal-btn:hover { background: var(--primary-hover); }
.portal-note { color: var(--muted-color); font-size: .95rem; margin-top: .5rem; }

/* Actions row */
.actions { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; margin: .6rem 0 .8rem 0; }

/* Media sizing */
img, svg, video, canvas { max-width: 100%; height: auto; }
.hw-iframe-container iframe { max-width: 100%; }

/* Transcript header layout */
.transcript-header { display: flex; align-items: center; gap: 1rem; flex-wrap: wrap; }
.transcript-logo { width: 56px; height: 56px; border-radius: 10px; border: 1px solid var(--border-color); background: #fff; object-fit: cover; }
.transcript-title { flex: 1 1 auto; }
.transcript-heading { margin: .1rem 0 0 0; }
.transcript-actions { display: flex; gap: .5rem; align-self: flex-start; }

/* Tablet and mobile breakpoints */
@media (max-width: 1024px) {
  .grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 768px) {
  /* Header layout */
  .hero-inner { grid-template-columns: 1fr; gap: 1rem; }
  .brand { flex-direction: column; align-items: flex-start; justify-content: flex-start; gap: .5rem; }
  .logo { width: 44px; height: 44px; font-size: 1.3rem; }
  .titles h1 { font-size: 1.1rem; }

  /* Tabs: keep horizontal on mobile, allow scroll */
  .tabs {
    flex-direction: row;
    align-items: center;
    gap: 0.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
    overflow-x: auto;
  }
  .tab {
    display: inline-block;
    width: auto;
    white-space: nowrap;
    text-align: center;
    border: 1px solid transparent;
    background-color: transparent;
  }
  .tab.active { color: #fff; background-color: var(--primary-color); border-color: var(--primary-color); }

  /* Grid stacks */
  .grid.two { grid-template-columns: 1fr; }

  /* Card padding compacts */
  .card { padding: 1.25rem; }

  /* Selector layout stacks */
  .selector { display: flex; flex-direction: column; align-items: stretch; gap: .75rem; }
  #student-select { width: 100%; min-width: 0; }

  /* Portal fields stack */
  .portal-fields { grid-template-columns: 1fr; }
  .portal-or { display: none; }
  .portal-actions { display: flex; }

  /* Make wide tables scrollable */
  .table { display: block; overflow-x: auto; white-space: nowrap; }
  .table th, .table td { white-space: nowrap; }
}

@media (max-width: 420px) {
  .tab { padding: .45rem .8rem; font-size: .9rem; }
  .titles h1 { font-size: 1rem; }
}