:root {
  font-family: Georgia, 'Times New Roman', serif;
  color: #273142;
  background: #ffffff;
  --ink: #273142;
  --muted: #687386;
  --line: #d9dee7;
  --cream: #ffffff;
  --paper: #ffffff;
  --frost: #88c0d0;
  --blue: #5e81ac;
  --green: #a3be8c;
  --red: #bf616a;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; background: var(--cream); color: var(--ink); font-size: 15px; line-height: 1.45; }
button, input, select { font: inherit; }
button { cursor: pointer; }

.auth-screen { display: grid; min-height: 100vh; place-items: center; padding: 24px; background: #f7f9fb; }
.auth-panel { width: min(100%, 430px); padding: 38px; border: 1px solid var(--line); border-radius: 10px; background: #ffffff; box-shadow: 0 18px 50px rgba(39, 49, 66, .08); }
.brand-wordmark { margin: 0 0 11px; color: var(--blue); font: 700 clamp(36px, 8vw, 58px) Georgia, 'Times New Roman', serif; letter-spacing: -2px; line-height: 1; }
.auth-panel h2 { margin: 0 0 9px; color: var(--ink); font-size: clamp(25px, 5vw, 34px); font-weight: 400; letter-spacing: -1px; }
.auth-intro { margin: 0 0 25px; color: var(--muted); }
.auth-form { display: grid; gap: 15px; }
.auth-form label { display: grid; gap: 6px; color: var(--muted); font: 11px Arial, sans-serif; }
.auth-form label[hidden] { display: none; }
.auth-form input { width: 100%; border: 1px solid var(--line); border-radius: 4px; padding: 12px; color: var(--ink); background: #ffffff; }
.auth-form .primary-button { width: 100%; margin-top: 5px; }
.auth-toggle { margin-top: 18px; padding: 0; }
.auth-message { min-height: 20px; margin: 17px 0 0; color: var(--red); font: 12px Arial, sans-serif; }
.auth-message.success { color: #527044; }
.app-shell { display: none; }
.app-shell.ready { display: block; }

.app-shell { min-height: 100vh; }
.sidebar { display: flex; flex-direction: column; padding: 38px 27px; background: #ffffff; color: var(--ink); }
.brand { display: flex; align-items: center; gap: 10px; color: inherit; font: 700 20px Georgia, serif; text-decoration: none; letter-spacing: -.4px; }
.brand-mark { display: grid; place-items: center; width: 29px; height: 29px; border-radius: 8px 8px 8px 2px; background: var(--frost); color: var(--ink); font-family: Arial, sans-serif; }
.main-nav { display: grid; gap: 7px; margin-top: 80px; }
.nav-link { display: flex; align-items: center; gap: 12px; padding: 12px 13px; border-radius: 7px; color: #aeb7c6; text-decoration: none; }
.nav-link.active, .nav-link:hover { background: #eef3f7; color: var(--ink); }
.nav-icon { width: 18px; font: 18px Arial, sans-serif; text-align: center; }
.semester-card { display: grid; gap: 3px; margin-top: auto; padding: 16px; border: 1px solid var(--line); border-radius: 8px; color: var(--muted); font-size: 12px; }
.semester-card strong { color: var(--ink); font-size: 15px; }
.sidebar-note { margin: 18px 4px 0; color: var(--muted); font-size: 12px; }

.content { width: min(100%, 1280px); margin: 0 auto; padding: 38px clamp(25px, 5vw, 75px) 70px; }
.topbar, .page-heading, .section-heading { display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.topbar-actions { display: flex; align-items: center; gap: 22px; }
.page-nav { display: flex; align-items: center; gap: 5px; }
.page-nav .nav-link { padding: 8px 11px; border-radius: 5px; color: var(--muted); font: 700 11px Arial, sans-serif; text-decoration: none; }
.page-nav .nav-link:hover, .page-nav .nav-link.active { background: #eef3f7; color: var(--ink); }
.topbar .brand-wordmark { margin-bottom: 8px; font-size: clamp(32px, 4vw, 48px); }
.topbar h1 { margin: 0; font-size: clamp(24px, 3vw, 32px); letter-spacing: -.8px; }
.eyebrow { display: block; color: var(--muted); font: 700 10px Arial, sans-serif; letter-spacing: 1.3px; text-transform: uppercase; }
.profile-menu { position: relative; }
.avatar { width: 38px; height: 38px; border: 0; border-radius: 50%; background: var(--frost); color: var(--ink); font: 700 14px Arial, sans-serif; }
.avatar:hover, .avatar:focus-visible { background: var(--blue); color: #ffffff; }
.profile-menu-panel { position: absolute; top: calc(100% + 8px); right: 0; min-width: 125px; padding: 5px; border: 1px solid var(--line); border-radius: 6px; background: var(--paper); box-shadow: 0 10px 25px rgba(39, 49, 66, .14); z-index: 2; }
.profile-menu-panel[hidden] { display: none; }
.profile-menu-item { width: 100%; border: 0; border-radius: 4px; background: transparent; padding: 9px 11px; color: var(--ink); text-align: left; font: 700 12px Arial, sans-serif; }
.profile-menu-item:hover, .profile-menu-item:focus-visible { background: #eef3f7; }
.dark-mode { --ink: #eceff4; --muted: #d8dee9; --line: #4c566a; --cream: #2e3440; --paper: #3b4252; --frost: #88c0d0; --blue: #81a1c1; --green: #a3be8c; --red: #bf616a; }
.dark-mode .auth-screen, .dark-mode .auth-panel, .dark-mode .sidebar, .dark-mode .teacher-card, .dark-mode .modal, .dark-mode .profile-menu-panel { background: var(--paper); }
.dark-mode .auth-screen, .dark-mode .teacher-stats div, .dark-mode .class-counter div, .dark-mode .nav-link.active, .dark-mode .nav-link:hover, .dark-mode .page-nav .nav-link.active, .dark-mode .page-nav .nav-link:hover, .dark-mode .open-button, .dark-mode .profile-menu-item:hover, .dark-mode .profile-menu-item:focus-visible, .dark-mode .teacher-initial { background: #434c5e; }
.dark-mode .auth-form input, .dark-mode .teacher-stats div, .dark-mode .class-counter div { background: #434c5e; color: var(--ink); }
.dark-mode .auth-form input::placeholder { color: var(--muted); }
.dark-mode .auth-panel, .dark-mode .teacher-card { box-shadow: 0 18px 50px rgba(0, 0, 0, .18); }
.dark-mode .teacher-stats div, .dark-mode .class-counter div, .dark-mode .assignment-summary { background: #434c5e; }
.dark-mode .teacher-initial { color: #8fbcbb; }
.dark-mode .assignment-summary, .dark-mode .task-row { background: #3b4252; }
.dark-mode .task-row { border-color: var(--line); }
.dark-mode .modal input, .dark-mode .modal select { background: #434c5e; color: var(--ink); }
.dark-mode .delete-task { border-color: #70474f; background: #4b3037; }
.page-heading { margin: 68px 0 27px; align-items: end; }
.page-heading h2 { margin: 4px 0 0; font-size: clamp(31px, 5vw, 52px); line-height: 1; letter-spacing: -2px; font-weight: 400; }
.quiet-button, .primary-button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; border: 0; border-radius: 5px; background: var(--blue); color: #ffffff; padding: 11px 15px; font: 700 12px Arial, sans-serif; }
.quiet-button span { font-size: 18px; line-height: 12px; }

.section-block { margin-top: 56px; }
.section-heading { margin-bottom: 18px; }
.section-heading h3 { margin: 5px 0 0; font-size: 24px; font-weight: 400; letter-spacing: -.6px; }
.section-actions { display: flex; align-items: center; gap: 18px; }
.section-count { color: var(--muted); font: 12px Arial, sans-serif; }
.teacher-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 15px; }
.teacher-card { padding: 13px; border: 1px solid var(--line); border-radius: 7px; background: var(--paper); box-shadow: 0 3px 12px rgba(39, 49, 66, .05); transition: transform .2s ease, box-shadow .2s ease; }
.teacher-card:hover { transform: translateY(-3px); box-shadow: 0 10px 24px rgba(46, 52, 64, .12); }
.teacher-top { display: flex; align-items: start; justify-content: space-between; gap: 12px; }
.teacher-initial { display: grid; place-items: center; width: 43px; height: 43px; border-radius: 50%; background: #eef3f7; color: #47748a; font: 700 15px Arial, sans-serif; }
.teacher-card h4 { margin: 3px 0 0; font-size: 20px; font-weight: 400; }
.teacher-subject { display: grid; gap: 2px; margin: 6px 0 0; color: var(--ink); font-size: 13px; }
.teacher-subject span { color: var(--muted); font: 700 10px Arial, sans-serif; letter-spacing: 1px; text-transform: uppercase; }
.teacher-stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 4px; margin-top: 13px; }
.teacher-stats div { display: grid; gap: 2px; min-width: 0; padding: 6px 5px; border-top: 3px solid var(--blue); background: #f7f9fb; }
.teacher-stats div:nth-child(2) { border-top-color: var(--frost); }
.teacher-stats div:nth-child(3) { border-top-color: var(--green); }
.teacher-stats .absence-stat { border-top-color: var(--red); }
.teacher-stats strong { color: var(--ink); font: 700 17px Arial, sans-serif; }
.teacher-stats span { color: var(--muted); font: 10px Arial, sans-serif; text-transform: uppercase; }
.teacher-room { margin: 11px 0 0; color: var(--muted); font: 11px Arial, sans-serif; }
.class-counter { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; margin-top: 17px; }
.class-counter div { display: grid; gap: 2px; padding: 9px 8px; border: 1px solid var(--line); border-radius: 5px; background: #f7f9fb; }
.class-counter strong { color: var(--ink); font: 700 18px Arial, sans-serif; }
.class-counter span { color: var(--muted); font: 10px Arial, sans-serif; text-transform: uppercase; letter-spacing: .5px; }
.class-counter div:last-child strong, .class-counter div:last-child span { color: #e18b93; }
.semester-total { margin: 9px 0 0; color: var(--muted); font: 10px Arial, sans-serif; }
.teacher-actions { margin-top: 12px; padding-top: 10px; border-top: 1px solid var(--line); }
.action-label { display: block; margin-bottom: 5px; color: var(--muted); font: 700 10px Arial, sans-serif; letter-spacing: 1px; text-transform: uppercase; }
.action-buttons { display: flex; gap: 6px; }
.attendance-button, .open-button { flex: 1; border: 1px solid var(--line); border-radius: 4px; background: transparent; padding: 7px 5px; color: var(--muted); font: 700 11px Arial, sans-serif; }
.attendance-button.present { border-color: #75965f; background: #edf5e9; color: #416136; }
.attendance-button.present:hover, .attendance-button.present.selected { border-color: var(--green); background: #a3be8c; color: #273142; }
.attendance-button.absent { border-color: #c77a82; background: #fff0f1; color: #a84f59; }
.attendance-button.absent:hover, .attendance-button.absent.selected { border-color: var(--red); background: #bf616a; color: #ffffff; }
.open-button { flex: 1.3; background: #eef3f7; color: var(--ink); }
.undo-attendance { margin-top: 9px; border: 0; background: transparent; color: var(--muted); font: 700 10px Arial, sans-serif; }
.undo-attendance:hover { color: var(--blue); text-decoration: underline; }
.remove-teacher { margin-top: 6px; border: 0; background: transparent; color: #d9969d; font: 700 10px Arial, sans-serif; text-align: left; }
.remove-teacher:hover { color: var(--red); text-decoration: underline; }
.text-button { border: 0; background: transparent; color: var(--blue); font: 700 12px Arial, sans-serif; }

.task-list { display: grid; gap: 1px; border-top: 1px solid var(--line); }
.task-row { display: grid; grid-template-columns: 28px 1fr auto auto; align-items: center; gap: 12px; padding: 16px 4px; border-bottom: 1px solid var(--line); }
.task-check { width: 18px; height: 18px; accent-color: var(--blue); }
.task-title { margin: 0; font-size: 15px; }
.task-title.done { color: var(--muted); text-decoration: line-through; }
.task-meta { display: flex; flex-wrap: wrap; gap: 5px 12px; margin: 3px 0 0; color: var(--muted); font: 11px Arial, sans-serif; }
.task-meta strong { color: var(--ink); font-weight: 700; }
.task-due { color: var(--red); font: 11px Arial, sans-serif; }
.delete-task { display: grid; width: 30px; height: 30px; place-items: center; border: 1px solid #f0c8cc; border-radius: 5px; background: #fff5f6; color: var(--red); font-size: 17px; line-height: 1; }
.delete-task:hover { border-color: var(--red); background: var(--red); color: #ffffff; }
.empty-state { display: grid; gap: 4px; padding: 30px 4px; border-bottom: 1px solid var(--line); color: var(--muted); }
.empty-state strong { color: var(--ink); font-size: 16px; font-weight: 400; }
.empty-state span { font: 12px Arial, sans-serif; }
.assignment-heading { margin-bottom: 35px; }
.page-intro { max-width: 470px; margin: 14px 0 0; color: var(--muted); }
.assignment-summary { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; max-width: 680px; padding: 16px; border: 1px solid var(--line); border-radius: 8px; background: #f7f9fb; }
.assignment-summary div { display: grid; gap: 3px; padding: 4px 16px; border-left: 3px solid var(--blue); }
.assignment-summary div:nth-child(2) { border-left-color: var(--green); }
.assignment-summary div:nth-child(3) { border-left-color: var(--red); }
.assignment-summary strong { font: 700 25px Arial, sans-serif; }
.assignment-summary span { color: var(--muted); font: 10px Arial, sans-serif; letter-spacing: .8px; text-transform: uppercase; }
.assignment-section { margin-top: 48px; max-width: 920px; }

.modal-backdrop { position: fixed; inset: 0; display: grid; place-items: center; padding: 20px; background: rgba(39, 49, 66, .35); z-index: 5; }
.modal-backdrop[hidden] { display: none; }
.modal { position: relative; display: grid; gap: 14px; width: min(100%, 420px); padding: 30px; border-radius: 9px; background: var(--paper); box-shadow: 0 20px 60px rgba(46, 52, 64, .2); }
.modal h2 { margin: 0 0 8px; font-size: 29px; font-weight: 400; }
.modal label { display: grid; gap: 6px; color: var(--muted); font: 11px Arial, sans-serif; }
.modal input, .modal select { width: 100%; border: 1px solid var(--line); border-radius: 4px; padding: 11px; color: var(--ink); background: #ffffff; }
.modal-close { position: absolute; top: 15px; right: 17px; border: 0; background: transparent; color: var(--muted); font-size: 25px; line-height: 1; }
.primary-button { margin-top: 7px; padding: 13px; }
.detail-subject { margin: -7px 0 0; color: var(--muted); }
.detail-attendance { display: grid; gap: 10px; margin-top: 10px; padding-top: 16px; border-top: 1px solid var(--line); }
.detail-attendance div { display: flex; gap: 8px; }
.detail-attendance .attendance-button { flex: 1; }
.toast { position: fixed; right: 24px; bottom: 24px; padding: 12px 17px; border-radius: 4px; background: var(--ink); color: #ffffff; font: 12px Arial, sans-serif; opacity: 0; transform: translateY(10px); transition: .25s ease; pointer-events: none; }
.toast.show { opacity: 1; transform: translateY(0); }

@media (max-width: 720px) {
  .app-shell { display: block; }
  .sidebar { padding: 18px 20px; }
  .main-nav { display: flex; gap: 2px; margin: 22px 0 0; }
  .nav-link { padding: 8px 11px; font-size: 13px; }
  .semester-card, .sidebar-note { display: none; }
  .content { padding: 27px 20px 50px; }
  .topbar-actions { gap: 8px; }
  .page-nav .nav-link { padding: 7px 8px; }
  .page-heading { margin-top: 48px; }
  .teacher-grid { grid-template-columns: 1fr; }
  .section-block { margin-top: 42px; }
}

@media (max-width: 560px) {
  .section-heading { align-items: flex-start; flex-direction: column; gap: 10px; }
  .section-actions { width: 100%; justify-content: space-between; }
  .assignment-summary { width: 100%; }
}

@media (max-width: 430px) {
  .auth-panel { padding: 28px 22px; }
  .topbar .brand-wordmark { font-size: 35px; }
  .topbar h1 { font-size: 23px; }
  .topbar { align-items: flex-start; }
  .topbar-actions { align-items: flex-end; flex-direction: column-reverse; gap: 10px; }
  .page-nav .nav-link { font-size: 10px; }
  .page-heading { align-items: start; flex-direction: column; gap: 18px; }
  .page-heading h2 { font-size: 41px; }
  .quiet-button { width: 100%; }
  .task-row { grid-template-columns: 25px 1fr auto; }
  .task-due { grid-column: 2; }
  .delete-task { grid-column: 3; grid-row: 1 / span 2; }
  .teacher-actions { flex-wrap: wrap; }
  .teacher-card { padding: 11px; }
  .teacher-stats { gap: 4px; }
  .teacher-stats div { padding: 5px 4px; }
  .teacher-stats strong { font-size: 16px; }
  .attendance-button, .open-button { min-width: 29%; }
  .assignment-summary { gap: 4px; padding: 12px 8px; }
  .assignment-summary div { padding: 4px 8px; }
  .assignment-summary strong { font-size: 21px; }
}