:root {
    color-scheme: light;
    --bg: #f4f6f8;
    --surface: #ffffff;
    --surface-soft: #eef4f8;
    --input-bg: #fbfdff;
    --text: #15202b;
    --muted: #65717d;
    --border: #dce3ea;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-soft: #dbeafe;
    --accent: #0f766e;
    --secondary: #475569;
    --secondary-dark: #334155;
    --label: #334155;
    --icon-color: #0f172a;
    --hero-start: #ffffff;
    --hero-end: #eef7f6;
    --header-bg: rgba(255, 255, 255, 0.9);
    --selected-bg: #eff6ff;
    --danger-bg: #fee2e2;
    --danger-text: #991b1b;
    --danger-hover: #fecaca;
    --shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

body.theme-forest {
    --bg: #f1f7f2;
    --surface: #ffffff;
    --surface-soft: #e5f2e8;
    --input-bg: #fbfffc;
    --text: #173124;
    --muted: #607268;
    --border: #cadfd1;
    --primary: #15803d;
    --primary-dark: #166534;
    --primary-soft: #dcfce7;
    --accent: #0f766e;
    --secondary: #3f6250;
    --secondary-dark: #2f4d3d;
    --label: #294837;
    --icon-color: #12301f;
    --hero-start: #ffffff;
    --hero-end: #e5f5ea;
    --header-bg: rgba(255, 255, 255, 0.92);
    --selected-bg: #ecfdf5;
    --shadow: 0 18px 45px rgba(20, 83, 45, 0.09);
}

body.theme-sunrise {
    --bg: #f7f3ec;
    --surface: #ffffff;
    --surface-soft: #f3eadb;
    --input-bg: #fffdf8;
    --text: #2e2418;
    --muted: #7a6b5a;
    --border: #e5d8c4;
    --primary: #c2410c;
    --primary-dark: #9a3412;
    --primary-soft: #ffedd5;
    --accent: #0f766e;
    --secondary: #675246;
    --secondary-dark: #4f3f36;
    --label: #4b3b2e;
    --icon-color: #2e2418;
    --hero-start: #ffffff;
    --hero-end: #fff1df;
    --header-bg: rgba(255, 252, 247, 0.93);
    --selected-bg: #fff7ed;
    --shadow: 0 18px 45px rgba(154, 52, 18, 0.09);
}

body.theme-lavender {
    --bg: #f5f3f8;
    --surface: #ffffff;
    --surface-soft: #eee9f7;
    --input-bg: #fefcff;
    --text: #251e33;
    --muted: #6f6680;
    --border: #ded6ea;
    --primary: #7c3aed;
    --primary-dark: #6d28d9;
    --primary-soft: #ede9fe;
    --accent: #0f766e;
    --secondary: #5f5274;
    --secondary-dark: #4b405f;
    --label: #443856;
    --icon-color: #251e33;
    --hero-start: #ffffff;
    --hero-end: #f1ebfb;
    --header-bg: rgba(255, 255, 255, 0.92);
    --selected-bg: #f5f3ff;
    --shadow: 0 18px 45px rgba(91, 33, 182, 0.08);
}

body.theme-night {
    color-scheme: dark;
    --bg: #10151d;
    --surface: #17202b;
    --surface-soft: #1f2b38;
    --input-bg: #111923;
    --text: #edf2f7;
    --muted: #a7b2c1;
    --border: #2d3b4d;
    --primary: #38bdf8;
    --primary-dark: #0ea5e9;
    --primary-soft: #12384c;
    --accent: #5eead4;
    --secondary: #334155;
    --secondary-dark: #263445;
    --label: #dbeafe;
    --icon-color: #e2e8f0;
    --hero-start: #182433;
    --hero-end: #142b34;
    --header-bg: rgba(16, 21, 29, 0.9);
    --selected-bg: #172f42;
    --danger-bg: #4a1f29;
    --danger-text: #fecdd3;
    --danger-hover: #713042;
    --shadow: 0 18px 45px rgba(0, 0, 0, 0.28);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.5;
}

a {
    color: inherit;
}

header {
    background: var(--header-bg);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 10;
    backdrop-filter: blur(12px);
}

.topbar {
    align-items: center;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    margin: 0 auto;
    max-width: 1120px;
    padding: 0.9rem 1.25rem;
}

.brand {
    color: var(--text);
    font-size: 1.15rem;
    font-weight: 800;
    letter-spacing: 0;
    text-decoration: none;
}

nav {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
}

nav a {
    border-radius: 999px;
    color: var(--muted);
    font-size: 0.95rem;
    font-weight: 700;
    padding: 0.55rem 0.75rem;
    text-decoration: none;
}

nav a:hover {
    background: var(--surface-soft);
    color: var(--text);
}

nav a[aria-current="page"] {
    background: var(--primary-soft);
    color: var(--primary-dark);
}

.logout-form {
    display: block;
}

.nav-button {
    background: transparent;
    color: var(--muted);
    font-size: 0.95rem;
    min-height: auto;
    padding: 0.55rem 0.75rem;
}

.nav-button:hover {
    background: var(--surface-soft);
    box-shadow: none;
    color: var(--text);
    transform: none;
}

main {
    margin: 0 auto;
    max-width: 1120px;
    padding: 2rem 1.25rem 3rem;
}

h1,
h2,
h3,
p {
    margin-top: 0;
}

h1 {
    font-size: 2.6rem;
    line-height: 1.05;
    margin-bottom: 0.65rem;
}

h2 {
    font-size: 1.15rem;
    margin-bottom: 0.8rem;
}

.page-heading {
    align-items: center;
    background: linear-gradient(135deg, var(--hero-start) 0%, var(--hero-end) 100%);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: var(--shadow);
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    margin-bottom: 1.25rem;
    padding: 1.4rem;
}

.eyebrow {
    color: var(--accent);
    font-size: 0.8rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    margin-bottom: 0.45rem;
    text-transform: uppercase;
}

.muted {
    color: var(--muted);
    margin-bottom: 0;
}

.section-block,
.panel,
.form-shell {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 10px 26px rgba(15, 23, 42, 0.05);
    margin-bottom: 1rem;
    padding: 1.1rem;
}

.section-title {
    align-items: center;
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.9rem;
}

.heading-actions {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    justify-content: flex-end;
}

.section-title h2 {
    margin-bottom: 0;
}

.section-title a {
    color: var(--primary);
    font-weight: 800;
    text-decoration: none;
}

.login-shell {
    display: grid;
    min-height: calc(100vh - 160px);
    place-items: center;
}

.login-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: var(--shadow);
    max-width: 460px;
    padding: 1.4rem;
    width: 100%;
}

.alert-error {
    background: var(--danger-bg);
    border: 1px solid var(--danger-hover);
    border-radius: 8px;
    color: var(--danger-text);
    font-weight: 800;
    margin: 1rem 0;
    padding: 0.75rem 0.85rem;
}

button,
.button,
.small-button {
    align-items: center;
    background: var(--primary);
    border: 0;
    border-radius: 8px;
    color: white;
    cursor: pointer;
    display: inline-flex;
    font-size: 1rem;
    font-weight: 800;
    justify-content: center;
    min-height: 48px;
    padding: 0.78rem 1rem;
    text-decoration: none;
    transition: background 0.15s ease, box-shadow 0.15s ease, transform 0.15s ease;
}

button:hover,
.button:hover {
    background: var(--primary-dark);
    box-shadow: 0 10px 20px rgba(37, 99, 235, 0.22);
    transform: translateY(-1px);
}

button:disabled,
button[aria-busy="true"] {
    cursor: wait;
    opacity: 0.85;
    transform: none;
}

.loading-spinner {
    animation: spin 0.8s linear infinite;
    border: 2px solid rgba(255, 255, 255, 0.45);
    border-top-color: #ffffff;
    border-radius: 999px;
    display: none;
    height: 1rem;
    margin-right: 0.55rem;
    width: 1rem;
}

.loading-label {
    display: none;
}

.is-loading .loading-spinner,
.is-loading .loading-label {
    display: inline-block;
}

.is-loading .button-label {
    display: none;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.button.secondary {
    background: var(--secondary);
}

.button.secondary:hover {
    background: var(--secondary-dark);
}

.small-button {
    font-size: 0.9rem;
    min-height: 36px;
    padding: 0.45rem 0.7rem;
}

.secondary-button {
    background: var(--secondary);
}

.secondary-button:hover {
    background: var(--secondary-dark);
}

form {
    display: grid;
    gap: 1rem;
}

.field,
.field-row {
    display: grid;
    gap: 0.45rem;
}

.field-row {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
}

.date-input-row {
    align-items: center;
    display: grid;
    gap: 0.5rem;
    grid-template-columns: minmax(0, 1fr) 48px;
}

.date-picker-button {
    align-items: center;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    display: grid;
    min-height: 48px;
    place-items: center;
    position: relative;
}

.date-picker-button::before {
    background:
        linear-gradient(var(--icon-color), var(--icon-color)) 0 5px / 100% 2px no-repeat,
        linear-gradient(var(--icon-color), var(--icon-color)) 4px 0 / 2px 5px no-repeat,
        linear-gradient(var(--icon-color), var(--icon-color)) 13px 0 / 2px 5px no-repeat;
    border: 2px solid var(--icon-color);
    border-radius: 4px;
    content: "";
    height: 18px;
    width: 20px;
}

.date-picker-button:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-soft);
}

.date-picker-control {
    cursor: pointer;
    inset: 0;
    opacity: 0;
    padding: 0;
    position: absolute;
}

.date-picker-control::-webkit-calendar-picker-indicator {
    cursor: pointer;
    height: 100%;
    position: absolute;
    width: 100%;
}

.generation-settings {
    border-top: 1px solid var(--border);
    display: grid;
    gap: 1rem;
    margin-top: 0.5rem;
    padding-top: 1rem;
}

.slider-list {
    display: grid;
    gap: 0.8rem;
}

.slider-row {
    align-items: center;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 0.75rem;
    grid-template-columns: minmax(160px, 1fr) 2fr;
    padding: 0.75rem;
}

.slider-row small {
    color: var(--muted);
    display: block;
    font-size: 0.82rem;
    font-weight: 700;
    margin-top: 0.15rem;
}

.slider-row.is-hidden {
    display: none;
}

.generation-summary {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
}

label {
    color: var(--label);
    font-size: 0.92rem;
    font-weight: 800;
}

input,
select,
textarea {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    font-size: 1rem;
    min-height: 48px;
    padding: 0.75rem 0.85rem;
    width: 100%;
}

input:focus,
select:focus,
textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-soft);
    outline: none;
}

textarea {
    resize: vertical;
}

.student-grid,
.student-manage-grid,
.placeholder-grid,
.study-set-grid,
.source-page-grid,
.vocab-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.student-grid form {
    max-width: none;
}

.compact-grid {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.student-card {
    align-items: center;
    background: var(--input-bg);
    border: 1px solid var(--border);
    color: var(--text);
    display: grid;
    gap: 0.75rem;
    grid-template-columns: minmax(0, 1fr) auto;
    justify-content: stretch;
    min-height: 96px;
    text-align: left;
    width: 100%;
}

.student-card span {
    align-self: center;
    background: var(--primary-soft);
    border-radius: 999px;
    color: var(--primary-dark);
    display: inline-flex;
    font-size: 0.78rem;
    justify-self: end;
    margin-top: 0;
    padding: 0.18rem 0.5rem;
    white-space: nowrap;
}

.student-card.selected {
    background: var(--selected-bg);
    border-color: var(--primary);
    box-shadow: inset 0 0 0 1px var(--primary);
}

.student-card.compact {
    min-height: 78px;
}

.manage-card {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 1rem;
    padding: 1rem;
}

.manage-card.selected {
    border-color: var(--primary);
    box-shadow: inset 0 0 0 1px var(--primary);
}

.inline-edit {
    gap: 0.45rem;
}

.inline-controls {
    display: flex;
    gap: 0.6rem;
}

.inline-controls input {
    min-width: 0;
}

.inline-controls button {
    flex: 0 0 auto;
}

.danger-button {
    background: var(--danger-bg);
    color: var(--danger-text);
    width: 100%;
}

.danger-button.compact {
    min-height: 36px;
    padding: 0.45rem 0.7rem;
}

.danger-button:hover {
    background: var(--danger-hover);
    box-shadow: 0 10px 20px rgba(153, 27, 27, 0.14);
}

.list {
    display: grid;
    gap: 0.75rem;
}

.list-item {
    align-items: center;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    padding: 0.95rem;
}

.list-item a,
.study-card {
    color: var(--text);
    font-weight: 800;
    text-decoration: none;
}

.list-item p,
.study-card p,
.study-card small,
.panel p {
    color: var(--muted);
}

.list-item p {
    margin-bottom: 0;
}

.list-actions {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    justify-content: flex-end;
}

.dashboard-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: minmax(0, 1.5fr) minmax(280px, 0.8fr);
}

.dashboard-summary {
    display: grid;
    gap: 0.75rem;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.dashboard-summary div {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 0.2rem;
    padding: 0.85rem;
}

.dashboard-summary strong {
    font-size: 1.8rem;
    line-height: 1;
}

.dashboard-summary span {
    color: var(--muted);
    font-size: 0.85rem;
    font-weight: 800;
}

.dashboard-card-grid {
    display: grid;
    gap: 0.85rem;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.dashboard-card,
.review-item {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 0.85rem;
    padding: 0.95rem;
}

.dashboard-card-main,
.review-item {
    align-items: start;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
}

.dashboard-card h3 {
    font-size: 1.15rem;
    margin-bottom: 0.3rem;
}

.dashboard-card h3 a {
    color: var(--text);
    text-decoration: none;
}

.dashboard-stats,
.dashboard-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.45rem;
}

.dashboard-stats span {
    background: var(--surface-soft);
    border: 1px solid var(--border);
    border-radius: 999px;
    color: var(--muted);
    font-size: 0.78rem;
    font-weight: 800;
    padding: 0.25rem 0.55rem;
}

.context-chip.urgent {
    background: #fff7ed;
    border-color: #fed7aa;
    color: #c2410c;
}

.review-item p {
    color: var(--muted);
    margin: 0.25rem 0 0;
}

.review-actions {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: flex-end;
}

.pill,
.context-chip {
    background: #ecfdf5;
    border: 1px solid #bbf7d0;
    border-radius: 999px;
    color: #047857;
    display: inline-flex;
    font-size: 0.82rem;
    font-weight: 800;
    padding: 0.32rem 0.65rem;
    white-space: nowrap;
}

.context-chip {
    background: var(--surface-soft);
    border-color: var(--border);
    color: var(--muted);
}

.study-card {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 0.65rem;
    min-height: 180px;
    padding: 1rem;
    transition: border-color 0.15s ease, box-shadow 0.15s ease, transform 0.15s ease;
}

.study-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow);
    transform: translateY(-2px);
}

.study-card-main {
    color: inherit;
    display: grid;
    gap: 0.65rem;
    text-decoration: none;
}

.study-card h2 {
    font-size: 1.25rem;
    margin-bottom: 0;
}

.card-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin-top: auto;
}

.card-actions form {
    display: block;
}

.actions {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.action-form {
    display: block;
}

.help-text {
    color: var(--muted);
    font-size: 0.9rem;
    margin-bottom: 0;
}

.source-page-card {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: grid;
    gap: 0.8rem;
    overflow: hidden;
}

.source-page-card img {
    aspect-ratio: 4 / 3;
    background: var(--surface-soft);
    display: block;
    object-fit: cover;
    width: 100%;
}

.source-page-card div {
    padding: 0 0.9rem 0.9rem;
}

.source-page-card p {
    color: var(--muted);
    margin: 0.3rem 0 0;
}

.content-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.stack-list {
    display: grid;
    gap: 0.75rem;
}

.mini-card {
    align-items: start;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    padding: 0.9rem;
}

.mini-card p,
.mini-card small {
    color: var(--muted);
    display: block;
    margin: 0.3rem 0 0;
}

.panel {
    min-height: 170px;
}

.panel-icon {
    align-items: center;
    background: var(--surface-soft);
    border-radius: 999px;
    color: var(--accent);
    display: inline-flex;
    font-size: 0.8rem;
    font-weight: 900;
    height: 36px;
    justify-content: center;
    margin-bottom: 0.85rem;
    width: 36px;
}

.empty-state {
    background: var(--input-bg);
    border: 1px dashed #b6c2cf;
    border-radius: 8px;
    color: var(--muted);
    grid-column: 1 / -1;
    padding: 1.25rem;
}

.empty-state h2,
.empty-state h3 {
    color: var(--text);
    margin-bottom: 0.35rem;
}

.practice-card,
.feedback-panel,
.theory-box,
.test-question {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 10px 26px rgba(15, 23, 42, 0.05);
    margin-bottom: 1rem;
    padding: 1.1rem;
}

.feedback-panel {
    align-items: center;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
}

.feedback-panel.correct {
    border-color: #86efac;
}

.feedback-panel.needs-work {
    border-color: #fed7aa;
}

.answer-review {
    display: grid;
    gap: 0.75rem;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    margin: 1rem 0;
}

.answer-review div {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.8rem;
}

.answer-review p {
    color: var(--muted);
    margin: 0.35rem 0 0;
}

.mastery-meter {
    min-width: 170px;
}

.mastery-meter span {
    display: block;
    font-size: 1.7rem;
    font-weight: 900;
    margin-bottom: 0.35rem;
}

.mastery-meter div {
    background: var(--surface-soft);
    border-radius: 999px;
    height: 10px;
    overflow: hidden;
}

.mastery-meter i {
    background: var(--accent);
    display: block;
    height: 100%;
}

.mastery-meter small {
    color: var(--muted);
    display: block;
    font-weight: 800;
    margin-top: 0.35rem;
}

.theory-box {
    background: var(--surface-soft);
    box-shadow: none;
}

.choice-list {
    display: grid;
    gap: 0.65rem;
}

.choice-option {
    align-items: center;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    gap: 0.65rem;
    padding: 0.75rem;
}

.choice-option input {
    min-height: auto;
    width: auto;
}

.test-form {
    display: grid;
    gap: 1rem;
}

.feedback-list {
    color: var(--muted);
    margin: 0;
    padding-left: 1.25rem;
}

.feedback-list li + li {
    margin-top: 0.45rem;
}

@media (max-width: 760px) {
    .topbar,
    .page-heading,
    .heading-actions,
    .list-item,
    .mini-card,
    .feedback-panel {
        align-items: stretch;
        flex-direction: column;
    }

    nav {
        width: 100%;
    }

    nav a {
        background: var(--surface-soft);
        flex: 1 1 auto;
        text-align: center;
    }

    main {
        padding: 1rem;
    }

    .page-heading {
        padding: 1rem;
    }

    h1 {
        font-size: 2rem;
    }

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

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

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

    .student-card span {
        justify-self: start;
    }

    .inline-controls {
        flex-direction: column;
    }

    .button {
        width: 100%;
    }

    .list-actions {
        justify-content: flex-start;
    }

    .action-form button {
        width: 100%;
    }

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

    .dashboard-grid,
    .dashboard-card-grid {
        grid-template-columns: 1fr;
    }

    .dashboard-card-main,
    .review-item {
        align-items: stretch;
        flex-direction: column;
    }

    .review-actions {
        justify-content: flex-start;
    }

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

    .pill {
        width: fit-content;
    }
}