:root {
  --bg: #f4f6fb;
  --panel: #ffffff;
  --sidebar: #111827;
  --text: #182033;
  --muted: #77809a;
  --primary: #6c5ce7;
  --primary-soft: #eeebff;
  --blue: #3b82f6;
  --green: #20b486;
  --orange: #f59e5b;
  --border: #e7eaf1;
  --shadow: 0 16px 38px rgba(35, 42, 65, 0.06);
  --radius: 20px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
}

button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { color: inherit; }
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
h1, h2, h3, p { margin: 0; }
h1 { font-size: clamp(1.35rem, 2vw, 1.8rem); letter-spacing: -0.04em; }
h2 { font-size: 1.1rem; letter-spacing: -0.02em; }
h3 { font-size: 0.9rem; }

:focus-visible { outline: 3px solid rgba(108, 92, 231, 0.35); outline-offset: 3px; }

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0e1420;
  --panel: #171f2e;
  --text: #edf1fb;
  --muted: #99a4bb;
  --border: #2a3548;
  --primary-soft: #29264b;
  --shadow: 0 16px 38px rgba(0, 0, 0, 0.18);
}

html[data-theme="dark"] .search,
html[data-theme="dark"] .notification,
html[data-theme="dark"] .progress-ring::before,
html[data-theme="dark"] .dialog { background: var(--panel); color: var(--text); }
html[data-theme="dark"] .icon-button,
html[data-theme="dark"] .date-strip button,
html[data-theme="dark"] .progress-stats > div,
html[data-theme="dark"] .lesson__mode,
html[data-theme="dark"] .dialog input,
html[data-theme="dark"] .secondary-button { background: #222c3d; color: var(--text); }
html[data-theme="dark"] .date-strip button.selected { background: var(--primary); }
html[data-theme="dark"] .notification__badge { border-color: var(--panel); }

.skip-link { position: fixed; z-index: 100; top: 12px; left: 12px; padding: 10px 14px; border-radius: 8px; background: #fff; transform: translateY(-150%); }
.skip-link:focus { transform: translateY(0); }

.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 30;
  display: flex;
  width: 252px;
  padding: 28px 20px 22px;
  flex-direction: column;
  justify-content: space-between;
  overflow-y: auto;
  background: var(--sidebar);
  color: #fff;
}

.brand { display: flex; align-items: center; gap: 10px; padding: 0 8px; font-size: 1.25rem; font-weight: 800; letter-spacing: -0.04em; }
.brand > span:last-child span { color: #9d8cff; }
.brand__mark { display: grid; width: 38px; height: 38px; place-items: center; border-radius: 12px; background: var(--primary); }
.primary-button, .secondary-button { display: inline-flex; min-height: 42px; padding: 0 16px; align-items: center; justify-content: center; gap: 8px; border: 0; border-radius: 11px; cursor: pointer; font-weight: 700; }
.primary-button { background: var(--primary); color: #fff; }
.secondary-button { background: #eef0f5; }
.sidebar__add { width: 100%; margin: 30px 0 28px; }
.navigation__label, .eyebrow { color: var(--muted); font-size: 0.7rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; }
.navigation__label { padding: 0 12px 10px; color: #69738b; }
.navigation__list { display: grid; margin: 0; padding: 0; gap: 5px; list-style: none; }
.navigation__item { display: flex; min-height: 46px; padding: 0 13px; align-items: center; gap: 13px; border-radius: 11px; color: #98a2b8; font-size: 0.86rem; font-weight: 600; transition: 0.2s ease; }
.navigation__item i { width: 18px; text-align: center; }
.navigation__item:hover, .navigation__item.active { background: rgba(108, 92, 231, 0.16); color: #fff; }
.navigation__item.active { box-shadow: inset 3px 0 #8e7dff; }
.navigation__badge { min-width: 24px; margin-left: auto; padding: 3px 7px; border-radius: 20px; background: #ef6675; color: #fff; font-size: 0.68rem; text-align: center; }
.profile { display: flex; padding: 14px 10px 0; align-items: center; gap: 10px; border-top: 1px solid rgba(255,255,255,0.08); }
.profile__avatar { width: 40px; height: 40px; border: 2px solid #8e7dff; border-radius: 50%; object-fit: cover; }
.profile__details { min-width: 0; flex: 1; }
.profile__details strong, .profile__details span { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.profile__details strong { font-size: 0.76rem; }
.profile__details span { margin-top: 4px; color: #8f99af; font-size: 0.67rem; }

.page-shell { min-height: 100vh; margin-left: 252px; }
.topbar { display: flex; min-height: 100px; padding: 22px 30px; align-items: center; gap: 18px; }
.topbar .eyebrow { margin-bottom: 6px; }
.topbar__actions { display: flex; margin-left: auto; align-items: center; gap: 12px; }
.search { display: flex; width: min(300px, 30vw); height: 44px; padding: 0 14px; align-items: center; gap: 9px; border: 1px solid transparent; border-radius: 12px; background: #fff; color: var(--muted); box-shadow: 0 8px 24px rgba(35,42,65,0.04); }
.search:focus-within { border-color: #b9adff; }
.search input { width: 100%; border: 0; outline: 0; background: transparent; color: var(--text); font-size: 0.78rem; }
.icon-button { display: inline-grid; width: 38px; height: 38px; flex: 0 0 auto; place-items: center; border: 0; border-radius: 10px; background: #f3f5f9; cursor: pointer; }
.icon-button:hover { background: var(--primary-soft); color: var(--primary); }
.icon-button--dark { background: rgba(255,255,255,0.07); color: #aab2c3; }
.notification { position: relative; width: 44px; height: 44px; background: #fff; box-shadow: 0 8px 24px rgba(35,42,65,0.04); }
.notification__badge { position: absolute; top: 8px; right: 8px; width: 8px; height: 8px; border: 2px solid #fff; border-radius: 50%; background: #ef6675; }
.menu-button { display: none; }

.dashboard { display: grid; padding: 0 30px 30px; grid-template-columns: minmax(0, 1.65fr) minmax(280px, 0.75fr); gap: 22px; }
.panel { min-width: 0; padding: 22px; border: 1px solid rgba(231,234,241,0.8); border-radius: var(--radius); background: var(--panel); box-shadow: var(--shadow); }
html[data-theme="dark"] .panel { border-color: var(--border); }
.section-heading { display: flex; margin-bottom: 20px; align-items: center; justify-content: space-between; gap: 15px; }
.section-heading .eyebrow { margin-bottom: 6px; }
.text-link { color: var(--primary); font-size: 0.72rem; font-weight: 700; }
.text-link i { margin-left: 4px; }

.overview { display: grid; grid-column: 1/-1; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; }
.metric-card { display: flex; min-width: 0; padding: 17px; align-items: center; gap: 13px; border: 1px solid var(--border); border-radius: 16px; background: var(--panel); box-shadow: var(--shadow); }
.metric-card__icon { display: grid; width: 44px; height: 44px; flex: 0 0 auto; place-items: center; border-radius: 13px; }
.metric-card__icon--purple { background: var(--primary-soft); color: var(--primary); }
.metric-card__icon--blue { background: #e5f1ff; color: var(--blue); }
.metric-card__icon--orange { background: #fff0e5; color: var(--orange); }
.metric-card__icon--green { background: #e4f8f2; color: var(--green); }
.metric-card p { margin-bottom: 5px; overflow: hidden; color: var(--muted); font-size: 0.64rem; text-overflow: ellipsis; white-space: nowrap; }
.metric-card strong { display: block; margin-bottom: 4px; font-size: 1.18rem; letter-spacing: -0.04em; }
.metric-card div > span { display: block; color: var(--muted); font-size: 0.55rem; white-space: nowrap; }
.metric-card div > span i { margin-right: 3px; color: var(--green); }
html[data-theme="dark"] .metric-card__icon--blue { background: #1c3552; }
html[data-theme="dark"] .metric-card__icon--orange { background: #3c2d25; }
html[data-theme="dark"] .metric-card__icon--green { background: #183b35; }

.date-strip { display: grid; margin-bottom: 18px; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.date-strip button { display: grid; min-height: 62px; place-content: center; gap: 5px; border: 0; border-radius: 12px; background: #f7f8fb; cursor: pointer; }
.date-strip span { color: var(--muted); font-size: 0.65rem; }
.date-strip strong { font-size: 0.82rem; }
.date-strip button.selected { background: var(--primary); color: #fff; box-shadow: 0 9px 20px rgba(108,92,231,0.24); }
.date-strip button.selected span { color: #ddd8ff; }
.lesson-list { display: grid; gap: 10px; }
.lesson { position: relative; display: grid; min-height: 76px; padding: 12px 10px 12px 16px; grid-template-columns: 60px 4px 42px minmax(130px, 1fr) auto 38px; align-items: center; gap: 12px; border: 1px solid var(--border); border-radius: 14px; }
.lesson__time strong, .lesson__time span { display: block; }
.lesson__time strong { font-size: 0.82rem; }
.lesson__time span { margin-top: 4px; color: var(--muted); font-size: 0.62rem; }
.lesson__accent { width: 4px; height: 42px; border-radius: 8px; }
.lesson__accent--purple { background: var(--primary); }
.lesson__accent--green { background: var(--green); }
.lesson__icon { display: grid; width: 42px; height: 42px; place-items: center; border-radius: 12px; font-size: 1rem; }
.lesson__icon--purple { background: var(--primary-soft); color: var(--primary); }
.lesson__icon--green { background: #e4f8f2; color: var(--green); }
.lesson__content p { margin-top: 5px; color: var(--muted); font-size: 0.68rem; }
.lesson__mode { padding: 7px 10px; border-radius: 8px; background: #f6f7fa; color: var(--muted); font-size: 0.65rem; white-space: nowrap; }

.progress-panel { text-align: center; }
.progress-panel .section-heading { text-align: left; }
.progress-ring { display: grid; width: 150px; height: 150px; margin: 12px auto 24px; place-items: center; border-radius: 50%; background: conic-gradient(var(--primary) calc(var(--progress) * 1%), #eceefa 0); }
.progress-ring::before { content: ""; grid-area: 1/1; width: 118px; height: 118px; border-radius: 50%; background: #fff; }
.progress-ring div { z-index: 1; grid-area: 1/1; }
.progress-ring strong, .progress-ring span { display: block; }
.progress-ring strong { font-size: 1.55rem; }
.progress-ring span { margin-top: 3px; color: var(--muted); font-size: 0.68rem; }
.progress-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.progress-stats > div { display: flex; padding: 12px; align-items: center; gap: 9px; border-radius: 12px; background: #f8f9fc; text-align: left; }
.stat-icon { display: grid; width: 32px; height: 32px; place-items: center; border-radius: 9px; }
.stat-icon--purple { background: var(--primary-soft); color: var(--primary); }
.stat-icon--orange { background: #fff0e5; color: var(--orange); }
.progress-stats strong, .progress-stats span { display: block; }
.progress-stats strong { font-size: 0.72rem; }
.progress-stats span { margin-top: 3px; color: var(--muted); font-size: 0.58rem; }

.material-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.material-card { position: relative; display: flex; min-height: 214px; padding: 16px; flex-direction: column; justify-content: space-between; overflow: hidden; border-radius: 16px; color: #fff; }
.material-card--purple { background: linear-gradient(145deg, #7666eb, #5a4bd3); }
.material-card--blue { background: linear-gradient(145deg, #4d9af7, #3479d3); }
.material-card--orange { background: linear-gradient(145deg, #f5a765, #e68143); }
.material-card__top { display: flex; align-items: center; justify-content: space-between; }
.material-card__top span { padding: 5px 8px; border-radius: 7px; background: rgba(255,255,255,0.17); font-size: 0.58rem; }
.material-card__top button { border: 0; background: transparent; color: #fff; cursor: pointer; }
.material-card__art { position: absolute; top: 58px; right: 20px; color: rgba(255,255,255,0.18); font-size: 4.4rem; transform: rotate(-8deg); }
.material-card h3 { position: relative; margin-bottom: 6px; color: #fff; }
.material-card p { color: rgba(255,255,255,0.72); font-size: 0.62rem; }

.groups { grid-row: span 2; }
.group-list { display: grid; gap: 10px; }
.group { display: grid; padding: 12px; grid-template-columns: 44px minmax(0, 1fr) 34px; align-items: center; gap: 11px; border: 1px solid var(--border); border-radius: 13px; transition: 0.2s ease; }
.group:hover { border-color: #d8d2ff; }
.group__avatar, .avatar { display: grid; place-items: center; border-radius: 12px; font-weight: 700; }
.group__avatar { width: 44px; height: 44px; }
.group__avatar--purple, .avatar--purple { background: var(--primary-soft); color: var(--primary); }
.group__avatar--blue, .avatar--blue { background: #e5f1ff; color: var(--blue); }
.group__avatar--orange, .avatar--orange { background: #fff0e5; color: var(--orange); }
.group p { margin-top: 5px; color: var(--muted); font-size: 0.66rem; }
.group__toggle { width: 34px; height: 34px; }
.group__toggle i { transition: transform 0.2s ease; }
.group.expanded .group__toggle i { transform: rotate(180deg); }
.group__details { display: none; padding: 11px 3px 2px 55px; grid-column: 1/-1; grid-template-columns: 1fr 1fr; gap: 7px; border-top: 1px solid var(--border); color: var(--muted); font-size: 0.62rem; }
.group.expanded .group__details { display: grid; }
.group__details a { grid-column: 1/-1; color: var(--primary); font-weight: 700; }

.inbox { grid-column: 1/-1; }
.message-list { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.message { position: relative; display: grid; padding: 15px; grid-template-columns: 42px minmax(0, 1fr); gap: 11px; border: 1px solid var(--border); border-radius: 14px; }
.message.unread::before { content: ""; position: absolute; top: 12px; right: 12px; width: 7px; height: 7px; border-radius: 50%; background: var(--primary); }
.avatar { width: 42px; height: 42px; font-size: 0.7rem; }
.message__content > div { display: flex; padding-right: 10px; justify-content: space-between; gap: 8px; }
.message__content time { color: var(--muted); font-size: 0.58rem; white-space: nowrap; }
.message__content p { margin-top: 7px; color: var(--muted); font-size: 0.67rem; line-height: 1.5; }
.message__actions { display: flex; margin-top: 11px; padding-top: 10px; grid-column: 1/-1; justify-content: flex-end; gap: 7px; border-top: 1px solid var(--border); }
.reply-button { padding: 7px 12px; border: 0; border-radius: 8px; background: var(--primary-soft); color: var(--primary); cursor: pointer; font-size: 0.65rem; font-weight: 700; }
.message__actions .icon-button { width: 30px; height: 30px; color: #ef6675; }

.toast { position: fixed; z-index: 80; right: 24px; bottom: 24px; max-width: min(360px, calc(100vw - 48px)); padding: 12px 16px; border-radius: 11px; background: #20283a; color: #fff; box-shadow: 0 12px 30px rgba(0,0,0,0.18); font-size: 0.75rem; opacity: 0; pointer-events: none; transform: translateY(12px); transition: 0.2s ease; }
.toast.show { opacity: 1; transform: translateY(0); }
.searchable.hidden { display: none; }

.dialog { width: min(420px, calc(100% - 32px)); padding: 0; border: 0; border-radius: 18px; box-shadow: 0 24px 70px rgba(13,19,33,0.24); }
.dialog::backdrop { background: rgba(13,19,33,0.52); backdrop-filter: blur(3px); }
.dialog form { display: grid; padding: 24px; gap: 10px; }
.dialog__heading { display: flex; margin-bottom: 10px; align-items: flex-start; justify-content: space-between; }
.dialog__heading .eyebrow { margin-bottom: 5px; }
.dialog label { font-size: 0.72rem; font-weight: 700; }
.dialog input { width: 100%; height: 44px; padding: 0 12px; border: 1px solid var(--border); border-radius: 10px; outline: 0; }
.dialog input:focus { border-color: var(--primary); }
.dialog__actions { display: flex; margin-top: 12px; justify-content: flex-end; gap: 8px; }

@media (max-width: 1100px) {
  .overview { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .dashboard { grid-template-columns: minmax(0, 1fr) 300px; }
  .materials { grid-column: 1/-1; }
  .groups { grid-row: auto; }
  .inbox { grid-column: 1/-1; }
  .message-list { grid-template-columns: 1fr; }
}

@media (max-width: 820px) {
  .sidebar { transform: translateX(-100%); transition: transform 0.25s ease; }
  .sidebar.open { transform: translateX(0); }
  .sidebar-backdrop { position: fixed; z-index: 20; inset: 0; background: rgba(13,19,33,0.5); }
  .sidebar-backdrop:not([hidden]) { display: block; }
  .page-shell { margin-left: 0; }
  .menu-button { display: inline-grid; }
  .dashboard { grid-template-columns: minmax(0, 1fr); }
  .materials, .inbox { grid-column: auto; }
}

@media (max-width: 620px) {
  .topbar { min-height: auto; padding: 18px 16px; flex-wrap: wrap; }
  .topbar > div:nth-child(2) { flex: 1; }
  .topbar__actions { width: 100%; margin: 0; }
  .search { width: auto; flex: 1; }
  .dashboard { padding: 0 16px 24px; gap: 16px; }
  .overview { grid-template-columns: 1fr; }
  .panel { padding: 17px; border-radius: 16px; }
  .lesson { grid-template-columns: 52px 3px 38px minmax(0,1fr) 34px; gap: 8px; }
  .lesson__icon { width: 38px; height: 38px; }
  .lesson__mode { display: none; }
  .material-grid { grid-template-columns: 1fr; }
  .material-card { min-height: 170px; }
  .material-card__art { top: 52px; }
  .progress-stats { grid-template-columns: 1fr; }
  .message__content > div { display: block; }
  .message__content time { display: block; margin-top: 4px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}