:root {
    --bg: #f8fafc;
    --bg2: #f1f5f9;
    --surface: #ffffff;
    --border: #cbd5e1;
    --text: #1e293b;
    --text-muted: #64748b;
    --accent: #3b82f6;
    --accent2: #2563eb;
    --accent3: #1d4ed8;
    --accent-light: #dbeafe;
    --accent-soft: #eff6ff;
    --success: #16a34a;
    --danger: #dc2626;
    --warning: #f59e0b;
    --cyan: #0891b2;
    --violet: #7c3aed;
    --font-head: 'Georgia', 'Times New Roman', serif;
    --font-body: 'OpenDyslexic', 'Atkinson Hyperlegible', 'Verdana', 'Arial', sans-serif;
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.25s ease;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.1);
    --max-w: 1100px;
}

/* ─── DARK THEME ─── */
[data-theme="dark"] {
    --bg: #0f172a;
    --bg2: #1e293b;
    --surface: #1e293b;
    --border: #334155;
    --text: #f1f5f9;
    --text-muted: #94a3b8;
    --accent: #60a5fa;
    --accent2: #93c5fd;
    --accent3: #bfdbfe;
    --accent-light: #1e3a5f;
    --accent-soft: #172554;
    --success: #4ade80;
    --danger: #f87171;
    --warning: #fbbf24;
    --cyan: #22d3ee;
    --violet: #a78bfa;
    --shadow: 0 1px 3px rgba(0,0,0,0.3), 0 1px 2px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.35);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.45);
}

[data-theme="dark"] .navbar {
    background: rgba(15, 23, 42, 0.92);
}

[data-theme="dark"] .nav-links.open {
    background: var(--surface);
}

/* ─── THEME TOGGLE BUTTON ─── */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 2px solid var(--border);
    background: var(--surface);
    cursor: pointer;
    transition: all var(--transition);
    flex-shrink: 0;
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-left: 0.4rem;
}

.theme-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-soft);
    transform: rotate(20deg);
}

*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.75;
    letter-spacing: 0.01em;
    word-spacing: 0.05em;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
    font-family: var(--font-head);
    letter-spacing: -0.02em;
    line-height: 1.2;
    font-weight: 700;
}

p { margin-bottom: 1rem; }
a { color: var(--accent2); text-decoration: none; }
img { max-width: 100%; height: auto; }

.container {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 20px;
}

.section-heading {
    font-size: clamp(1.6rem, 3.5vw, 2.2rem);
    font-weight: 800;
    margin-bottom: 0.5rem;
    color: var(--text);
}

.section-sub {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 2rem;
    max-width: 600px;
    line-height: 1.7;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.7rem 1.5rem;
    border: 2px solid transparent;
    border-radius: 100px;
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: all var(--transition);
    white-space: nowrap;
    letter-spacing: 0.02em;
}

.btn-accent {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.25);
}

.btn-accent:hover {
    background: var(--accent2);
    border-color: var(--accent2);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
}

.btn-ghost {
    background: transparent;
    color: var(--text);
    border-color: var(--border);
}

.btn-ghost:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-soft);
}

.btn-lg { padding: 0.9rem 2.2rem; font-size: 1rem; }
.btn-sm { padding: 0.45rem 1rem; font-size: 0.85rem; }

.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: var(--accent-light);
    color: var(--accent2);
    font-size: 0.8rem;
    font-weight: 700;
    padding: 0.3rem 0.9rem;
    border-radius: 100px;
    letter-spacing: 0.03em;
    text-transform: uppercase;
}

.badge-dot {
    width: 7px;
    height: 7px;
    background: var(--accent);
    border-radius: 50%;
    animation: pulse-dot 1.8s ease-in-out infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.4; transform: scale(1.6); }
}

.tag {
    display: inline-block;
    padding: 0.35rem 0.85rem;
    border-radius: 100px;
    border: 1.5px solid var(--border);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    background: var(--surface);
    letter-spacing: 0.02em;
}

/* ─── NAVBAR ─── */
.navbar {
    position: sticky;
    top: 0;
    z-index: 999;
    background: rgba(248, 250, 252, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 0;
    transition: all var(--transition);
}

.nav-inner {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0.6rem 20px;
    height: 60px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    font-family: var(--font-head);
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text);
    flex-shrink: 0;
}

.logo-icon { font-size: 1.4rem; }

.nav-links {
    display: flex;
    list-style: none;
    gap: 0.2rem;
    margin-left: auto;
}

.nav-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 600;
    padding: 0.4rem 0.7rem;
    border-radius: 100px;
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.nav-links a:hover,
.nav-links a:focus {
    color: var(--text);
    background: var(--accent-soft);
}

.nav-cta { margin-left: 0.5rem; flex-shrink: 0; }

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.4rem;
    margin-left: auto;
}

.hamburger span {
    display: block;
    width: 24px;
    height: 2.5px;
    background: var(--text);
    border-radius: 3px;
    transition: all var(--transition);
}

.hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ─── HERO ─── */
.hero {
    padding: 3rem 0 4rem;
    background: var(--bg);
    position: relative;
    overflow: hidden;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-badge { margin-bottom: 1.2rem; }

.hero-heading {
    font-size: clamp(2rem, 4.5vw, 3.2rem);
    font-weight: 900;
    margin-bottom: 1rem;
    line-height: 1.1;
}

.hero-heading .accent-text { color: var(--accent); }

.hero-sub {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 1.8rem;
    max-width: 480px;
    line-height: 1.7;
}

.hero-btns {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    margin-bottom: 1.5rem;
}

.hero-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.stat-pill {
    font-size: 0.8rem;
    padding: 0.35rem 0.8rem;
    border-radius: 100px;
    background: var(--accent-soft);
    border: 1.5px solid var(--accent-light);
    color: var(--accent2);
    font-weight: 600;
    letter-spacing: 0.02em;
}

.hero-right {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 360px;
    position: relative;
}

.formula-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 20px;
    padding: 2rem 1.8rem;
    width: 280px;
    text-align: center;
    box-shadow: var(--shadow-lg);
    animation: card-float 5s ease-in-out infinite;
    position: relative;
}

@keyframes card-float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-12px); }
}

.formula-card-label {
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.12em;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-bottom: 0.4rem;
}

.formula-before {
    font-family: 'Courier New', monospace;
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent2);
    margin: 0.5rem 0;
}

.formula-arrow {
    font-size: 1.4rem;
    color: var(--accent);
    margin: 0.3rem 0;
    animation: arrow-bounce 1.2s ease-in-out infinite;
}

@keyframes arrow-bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(6px); }
}

.formula-after {
    font-size: 0.9rem;
    color: var(--text);
    line-height: 1.6;
    margin-top: 0.2rem;
}

.formula-after strong { color: var(--accent); }

.card-glow {
    position: absolute;
    inset: -2px;
    border-radius: 22px;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.15), rgba(8, 145, 178, 0.1));
    pointer-events: none;
    z-index: -1;
    animation: glow-pulse 3s ease-in-out infinite;
}

@keyframes glow-pulse {
    0%, 100% { opacity: 0.5; }
    50% { opacity: 1; }
}

/* ─── SECTIONS ─── */
section { padding: 4rem 0; }
.bg-alt { background: var(--bg2); }

/* ─── SELECTOR ─── */
.selector-section { text-align: center; }

.subject-toggle {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1.8rem;
    flex-wrap: wrap;
}

.subject-btn {
    padding: 0.9rem 2.5rem;
    border-radius: 14px;
    border: 2.5px solid var(--border);
    background: var(--surface);
    color: var(--text-muted);
    font-family: var(--font-body);
    font-size: 1.05rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.subject-btn:hover { border-color: var(--accent); color: var(--accent); }

.subject-btn.active {
    border-color: var(--accent);
    background: var(--accent-soft);
    color: var(--accent2);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.08);
}

.level-cards {
    display: flex;
    justify-content: center;
    gap: 0.8rem;
    flex-wrap: wrap;
    margin-bottom: 1.2rem;
}

.level-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.3rem;
    padding: 1.2rem 1.4rem;
    border-radius: var(--radius);
    border: 2.5px solid var(--border);
    background: var(--surface);
    cursor: pointer;
    transition: all var(--transition);
    min-width: 140px;
    font-family: var(--font-body);
    letter-spacing: 0.02em;
}

.level-card:hover {
    border-color: var(--accent);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.level-card.active {
    border-color: var(--accent);
    background: var(--accent-soft);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.08);
}

.level-icon { font-size: 1.8rem; }
.level-title { font-weight: 700; font-size: 0.9rem; color: var(--text); }
.level-age { font-size: 0.75rem; color: var(--text-muted); }

.selector-info { color: var(--text-muted); font-size: 0.9rem; }
.selector-info strong { color: var(--accent2); }

/* ─── INPUT ─── */
.input-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 1.8rem;
    max-width: 750px;
    margin: 0 auto;
    box-shadow: var(--shadow-md);
}

.textarea-wrap {
    position: relative;
    margin-bottom: 1.2rem;
}

textarea {
    width: 100%;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-family: var(--font-body);
    font-size: 1rem;
    line-height: 1.7;
    padding: 1rem 1rem 2.8rem;
    resize: vertical;
    transition: border-color var(--transition);
    outline: none;
    min-height: 160px;
    letter-spacing: 0.02em;
    word-spacing: 0.05em;
}

textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.08);
}

textarea::placeholder { color: var(--text-muted); }

.textarea-footer {
    position: absolute;
    bottom: 0.6rem;
    left: 1rem;
    right: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.clear-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 0.9rem;
    padding: 0.3rem 0.5rem;
    border-radius: 50%;
    transition: all var(--transition);
    font-weight: 700;
}

.clear-btn:hover {
    color: var(--danger);
    background: rgba(220, 38, 38, 0.08);
}

.char-counter {
    font-size: 0.78rem;
    color: var(--text-muted);
    font-family: 'Courier New', monospace;
}

.input-actions {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.input-helper { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 1rem; }

.example-chips { display: flex; flex-wrap: wrap; gap: 0.4rem; align-items: center; }

.chip-label {
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-right: 0.2rem;
    font-weight: 600;
}

.chip {
    padding: 0.4rem 0.9rem;
    border-radius: 100px;
    border: 1.5px solid var(--border);
    background: var(--bg);
    color: var(--text-muted);
    font-size: 0.82rem;
    cursor: pointer;
    transition: all var(--transition);
    font-family: var(--font-body);
    letter-spacing: 0.02em;
}

.chip:hover { border-color: var(--accent); color: var(--accent2); background: var(--accent-soft); }
.chip.active { border-color: var(--accent); color: var(--accent2); background: var(--accent-soft); }

/* ─── OUTPUT ─── */
.output-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 1.8rem;
    max-width: 750px;
    margin: 0 auto;
    min-height: 250px;
    box-shadow: var(--shadow-md);
}

.output-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.8rem;
    margin-bottom: 1.2rem;
}

.level-badge {
    font-size: 0.78rem;
    font-weight: 700;
    padding: 0.35rem 0.9rem;
    border-radius: 100px;
    background: var(--accent-soft);
    border: 1.5px solid var(--accent-light);
    color: var(--accent2);
    letter-spacing: 0.03em;
}

.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    padding: 3rem 0;
    color: var(--text-muted);
}

.loader-ring {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}

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

.tab-bar {
    display: flex;
    gap: 0.3rem;
    border-bottom: 2px solid var(--border);
    margin-bottom: 1.2rem;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 0.55rem 1rem;
    border: none;
    background: none;
    color: var(--text-muted);
    font-family: var(--font-body);
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
    transition: all var(--transition);
    border-radius: 8px 8px 0 0;
    letter-spacing: 0.02em;
}

.tab-btn:hover { color: var(--text); background: var(--accent-soft); }
.tab-btn.active { color: var(--accent2); border-bottom-color: var(--accent); }

.tab-panel {
    font-size: 1rem;
    line-height: 1.8;
    color: var(--text);
    animation: fade-in 0.3s ease;
    padding: 0.5rem 0;
    letter-spacing: 0.02em;
    word-spacing: 0.05em;
}

@keyframes fade-in {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

.tab-panel p { margin-bottom: 0.8rem; }
.tab-panel ol { padding-left: 1.5rem; margin-bottom: 1rem; }
.tab-panel ol li { margin-bottom: 0.6rem; padding-left: 0.2rem; }
.tab-panel strong { color: var(--accent2); }

.quiz-q { margin-bottom: 1.2rem; padding: 0.8rem; background: var(--bg); border-radius: var(--radius-sm); }
.quiz-q p.q-text { font-weight: 700; margin-bottom: 0.5rem; color: var(--text); }

.quiz-option,
.quiz-bank-option {
    display: block;
    width: 100%;
    text-align: left;
    padding: 0.6rem 1rem;
    margin-bottom: 0.35rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--surface);
    color: var(--text);
    font-family: var(--font-body);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.quiz-option:hover,
.quiz-bank-option:hover { border-color: var(--accent); background: var(--accent-soft); }
.quiz-option.correct,
.quiz-bank-option.correct { border-color: var(--success); background: #f0fdf4; color: var(--success); font-weight: 700; }
.quiz-option.wrong,
.quiz-bank-option.wrong { border-color: var(--danger); background: #fef2f2; color: var(--danger); }
.quiz-option:disabled,
.quiz-bank-option:disabled { cursor: default; opacity: 0.8; }

.term-card {
    padding: 0.8rem 1rem;
    margin-bottom: 0.5rem;
    background: var(--bg);
    border-radius: var(--radius-sm);
    border-left: 4px solid var(--accent);
}

.term-card strong { color: var(--accent2); }

.empty-state { text-align: center; padding: 3rem 1rem; color: var(--text-muted); }
.empty-state.small { padding: 1.5rem 1rem; }
.empty-icon { font-size: 2.5rem; margin-bottom: 0.8rem; }

.output-actions {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 1.2rem;
    padding-top: 1.2rem;
    border-top: 2px solid var(--border);
}

/* ─── STUDY TOOLS ─── */
.form-label {
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-muted);
}

.section-head.split {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.section-pill {
    padding: 0.4rem 0.9rem;
    border-radius: 999px;
    background: var(--accent-soft);
    border: 1.5px solid var(--accent-light);
    color: var(--accent2);
    font-weight: 700;
    font-size: 0.78rem;
    letter-spacing: 0.03em;
}

.panel-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 1.2rem;
    display: flex;
    flex-direction: column;
    gap: 0.7rem;
    box-shadow: var(--shadow-sm);
}

.panel-card h3 {
    font-size: 1rem;
    margin-bottom: 0.3rem;
}

.panel-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.8rem;
}

.panel-actions {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.filter-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
}

.switch-row {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.switch {
    position: relative;
    display: inline-block;
    width: 42px;
    height: 22px;
}

.switch input { display: none; }

.switch-slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background: var(--border);
    border-radius: 999px;
    transition: all var(--transition);
}

.switch-slider::before {
    content: "";
    position: absolute;
    height: 16px;
    width: 16px;
    left: 3px;
    top: 3px;
    background: var(--surface);
    border-radius: 50%;
    transition: all var(--transition);
}

.switch input:checked + .switch-slider {
    background: var(--accent);
}

.switch input:checked + .switch-slider::before {
    transform: translateX(20px);
}

.flashcard-layout {
    display: grid;
    grid-template-columns: 1fr 1.3fr;
    gap: 1.5rem;
    align-items: start;
}

.flashcard-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.flashcard-stage {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 20px;
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.flashcard-stats {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    margin-bottom: 1rem;
}

.stat-label {
    font-size: 0.7rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border);
    border-radius: 999px;
    overflow: hidden;
}

.progress-bar span {
    display: block;
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent), var(--accent2));
    transition: width 0.4s ease;
}

.stat-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.6rem;
}

.stat-row div {
    background: var(--bg);
    border-radius: 12px;
    padding: 0.6rem;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.stat-row strong {
    display: block;
    font-size: 1rem;
    color: var(--text);
}

.flashcard-viewport {
    margin: 1rem 0;
}

.flashcard-swipe {
    position: relative;
    width: 100%;
    min-height: 260px;
    perspective: 1200px;
    touch-action: pan-y;
    cursor: grab;
}

.flashcard-swipe:active { cursor: grabbing; }

.flashcard-inner {
    position: relative;
    width: 100%;
    min-height: 260px;
    transition: transform 0.6s ease;
    transform-style: preserve-3d;
}

.flashcard-inner.is-flipped {
    transform: rotateY(180deg);
}

.flashcard-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    font-size: 1.05rem;
    line-height: 1.6;
    box-shadow: var(--shadow-sm);
}

.flashcard-back {
    transform: rotateY(180deg);
}

.flashcard-face img {
    max-width: 100%;
    max-height: 200px;
    border-radius: 12px;
    margin-bottom: 0.8rem;
}

.flashcard-face pre {
    width: 100%;
    text-align: left;
    background: #0f172a;
    color: #e2e8f0;
    padding: 0.8rem;
    border-radius: 12px;
    font-size: 0.85rem;
    overflow-x: auto;
}

.flashcard-meta {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.flashcard-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    justify-content: center;
    margin-top: 0.8rem;
}

.flashcard-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 0.6rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.session-timer {
    font-size: 1.4rem;
    font-weight: 800;
    text-align: center;
    color: var(--accent2);
}

.quiz-layout {
    display: grid;
    grid-template-columns: 1fr 1.4fr;
    gap: 1.5rem;
}

.quiz-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.quiz-stage {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 20px;
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.quiz-questions { display: flex; flex-direction: column; gap: 1rem; }

.difficulty-row {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.quiz-actions {
    margin-top: 0.6rem;
}

.quiz-hint {
    margin-top: 0.5rem;
    padding: 0.6rem 0.8rem;
    background: rgba(59, 130, 246, 0.1);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--accent2);
    display: none;
}

.recommendation-card {
    background: var(--accent-soft);
    border-radius: 12px;
    padding: 0.8rem;
    color: var(--accent2);
    text-align: center;
}

.topic-list { display: flex; flex-direction: column; gap: 0.4rem; }

.rec-title { margin: 0; font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.08em; }

.topic-list p { margin-bottom: 0.4rem; font-size: 0.85rem; color: var(--text-muted); }

.modal {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.55);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 1rem;
}

.modal.open { display: flex; }

.modal-card {
    background: var(--surface);
    border-radius: 18px;
    padding: 1.8rem;
    width: min(420px, 100%);
    box-shadow: var(--shadow-lg);
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.modal-close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    border: none;
    background: none;
    font-size: 1rem;
    cursor: pointer;
    color: var(--text-muted);
}

.modal-sub {
    color: var(--text-muted);
    margin-top: -0.3rem;
}

.auth-tabs { display: flex; gap: 0.5rem; }
.auth-form { display: flex; flex-direction: column; gap: 0.6rem; }
.auth-form.hidden { display: none; }
.auth-status { min-height: 1.2rem; color: var(--text-muted); font-size: 0.85rem; }
.auth-session { display: flex; flex-direction: column; gap: 0.6rem; }

.nav-auth { margin-left: 0.3rem; }
.muted { color: var(--text-muted); font-size: 0.85rem; }

.tool-card {
    display: grid;
    grid-template-columns: 1.1fr 1fr;
    gap: 1.5rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 1.6rem;
    box-shadow: var(--shadow-md);
}

.tool-form {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.tool-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
}

.tool-field { flex: 1; min-width: 160px; }
.tool-selection { font-size: 0.85rem; color: var(--text-muted); }

.tool-actions {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.tool-output {
    background: var(--bg);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    min-height: 220px;
}

.tool-status { min-height: 1.2rem; font-size: 0.85rem; color: var(--text-muted); margin: 0; }

.flashcard-grid {
    display: grid;
    gap: 0.8rem;
}

.flashcard {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    transition: all var(--transition);
}

.flashcard.revealed { border-color: var(--accent); box-shadow: var(--shadow-sm); }

.flashcard-index {
    font-size: 0.7rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
}

.flashcard-front p { margin: 0.4rem 0 0; font-weight: 600; color: var(--text); }

.flashcard-back {
    margin-top: 0.7rem;
    padding-top: 0.6rem;
    border-top: 1px solid var(--border);
    color: var(--text);
    
}

.flashcard.revealed .flashcard-back { display: block; }

.flashcard-toggle { margin-top: 0.7rem; }

.quiz-explanation {
    margin-top: 0.6rem;
    padding: 0.6rem 0.8rem;
    background: var(--accent-soft);
    border-radius: var(--radius-sm);
    color: var(--accent2);
    font-size: 0.85rem;
    display: none;
}

/* ─── FEATURES ─── */
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; }

.feature-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 1.4rem;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.feature-card:hover { transform: translateY(-4px); border-color: var(--accent); box-shadow: var(--shadow-lg); }
.feature-icon { font-size: 1.8rem; display: block; margin-bottom: 0.6rem; }

.feature-tag {
    display: inline-block;
    font-size: 0.68rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    padding: 0.2rem 0.55rem;
    border-radius: 100px;
    background: var(--accent-soft);
    color: var(--accent2);
    border: 1.5px solid var(--accent-light);
    margin-bottom: 0.5rem;
}

.feature-card h3 { font-size: 1rem; margin-bottom: 0.3rem; }
.feature-card p { font-size: 0.85rem; color: var(--text-muted); line-height: 1.6; margin-bottom: 0; }

/* ─── SHOWCASE ─── */
.showcase-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }

.showcase-col {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 2rem;
}

.showcase-title { font-family: var(--font-head); font-size: 1.3rem; font-weight: 800; margin-bottom: 1rem; color: var(--accent2); }

.showcase-list { list-style: none; display: flex; flex-direction: column; gap: 0.5rem; }

.showcase-list li {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text);
    padding: 0.5rem 0.7rem;
    border-radius: var(--radius-sm);
    background: var(--bg);
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.showcase-list li::before { content: '→'; color: var(--accent); font-weight: 700; flex-shrink: 0; }
.showcase-list li:hover { background: var(--accent-soft); }

/* ─── HOW IT WORKS ─── */
.steps-row { display: flex; align-items: flex-start; gap: 0; flex-wrap: wrap; }

.step-card { flex: 1; min-width: 200px; text-align: center; padding: 1.5rem 1rem; position: relative; }

.step-num {
    font-family: 'Courier New', monospace;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--accent);
    letter-spacing: 0.1em;
    margin-bottom: 0.5rem;
}

.step-icon { font-size: 2rem; display: block; margin-bottom: 0.8rem; }
.step-card h3 { font-size: 1rem; margin-bottom: 0.4rem; }
.step-card p { font-size: 0.85rem; color: var(--text-muted); line-height: 1.6; margin-bottom: 0; }

.step-connector {
    width: 50px;
    height: 2px;
    background: var(--accent-light);
    align-self: center;
    flex-shrink: 0;
    margin-top: -1rem;
    display: block;
}

/* ─── STATS ─── */
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; margin-bottom: 2rem; }

.stat-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    transition: all var(--transition);
}

.stat-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.stat-card.accent-stat { border-color: var(--accent-light); background: var(--accent-soft); }

.stat-num {
    font-family: var(--font-head);
    font-size: 2.4rem;
    font-weight: 900;
    color: var(--accent);
    display: block;
    margin-bottom: 0.4rem;
    line-height: 1;
}

.stat-label { font-size: 0.85rem; color: var(--text-muted); line-height: 1.5; }

.pull-quote {
    text-align: center;
    font-size: 1.1rem;
    font-style: italic;
    color: var(--text-muted);
    border-left: 4px solid var(--accent);
    padding: 1rem 1.5rem;
    max-width: 650px;
    margin: 0 auto;
    background: var(--accent-soft);
    border-radius: 0 var(--radius) var(--radius) 0;
    letter-spacing: 0.03em;
    line-height: 1.7;
}

/* ─── TESTIMONIALS ─── */
.testimonials-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.2rem; }

.testimonial-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    padding: 1.8rem;
    position: relative;
    transition: all var(--transition);
}

.testimonial-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); border-color: var(--accent-light); }

.quote-mark {
    font-size: 3.5rem;
    line-height: 0.6;
    color: var(--accent);
    font-family: Georgia, serif;
    margin-bottom: 0.6rem;
    display: block;
    opacity: 0.5;
}

.testimonial-card p { font-size: 0.95rem; color: var(--text); line-height: 1.7; margin-bottom: 0.8rem; letter-spacing: 0.02em; }
.testimonial-author { font-size: 0.82rem; color: var(--accent2); font-weight: 700; }

/* ─── ABOUT ─── */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; align-items: center; }

.about-text p {
    color: var(--text-muted);
    margin-bottom: 0.9rem;
    font-size: 0.95rem;
    line-height: 1.8;
    letter-spacing: 0.02em;
}

.about-highlight {
    font-size: 1rem !important;
    color: var(--text) !important;
    font-weight: 600;
    border-left: 4px solid var(--accent);
    padding-left: 1rem;
    margin: 1.2rem 0 !important;
}

.about-tags { display: flex; gap: 0.6rem; flex-wrap: wrap; margin-top: 1.2rem; }
.about-visual { display: flex; flex-direction: column; align-items: center; gap: 1rem; }
.about-card-stack { display: flex; flex-wrap: wrap; gap: 0.5rem; justify-content: center; margin-bottom: 1rem; }

.about-mini-card {
    padding: 0.6rem 1.2rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 0.85rem;
    font-weight: 700;
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.about-mini-card:hover { border-color: var(--accent); transform: translateY(-2px); }

.about-big-text {
    font-family: var(--font-head);
    font-size: 2rem;
    font-weight: 900;
    line-height: 1.2;
    color: var(--accent);
    text-align: center;
}

/* ─── COMPARISON ─── */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    border: 2px solid var(--border);
}

.comparison-table th,
.comparison-table td {
    padding: 0.9rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
    font-size: 0.9rem;
    letter-spacing: 0.02em;
}

.comparison-table th {
    background: var(--accent-soft);
    font-weight: 800;
    color: var(--accent2);
    font-family: var(--font-head);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

.comparison-table tr:last-child td { border-bottom: none; }
.comparison-table .check { color: var(--success); font-weight: 700; }
.comparison-table .cross { color: var(--danger); }
.comparison-table .partial { color: var(--warning); }
.comparison-table .highlight-col { background: var(--accent-soft); }

.comparison-cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; margin-top: 1.5rem; }

.comparison-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 1.4rem;
    text-align: center;
    transition: all var(--transition);
}

.comparison-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); border-color: var(--accent); }
.comparison-card .comp-icon { font-size: 2rem; margin-bottom: 0.6rem; display: block; }
.comparison-card h4 { font-size: 0.9rem; margin-bottom: 0.3rem; color: var(--accent2); }
.comparison-card p { font-size: 0.8rem; color: var(--text-muted); margin-bottom: 0; line-height: 1.5; }

/* ─── FUTURE ─── */
.future-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }

.future-card {
    background: var(--surface);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 1.4rem;
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.future-card.future-link {
    text-decoration: none;
    color: inherit;
}

.future-card:hover { border-color: var(--accent); transform: translateY(-3px); box-shadow: var(--shadow-md); }

.future-card .coming-soon {
    position: absolute;
    top: 0.6rem;
    right: 0.6rem;
    font-size: 0.6rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--violet);
    border: 1.5px solid rgba(124, 58, 237, 0.3);
    padding: 0.15rem 0.5rem;
    border-radius: 100px;
}

.future-card .coming-soon.live {
    color: var(--success);
    border-color: rgba(16, 185, 129, 0.35);
}

.future-card>span:first-of-type { font-size: 1.6rem; }
.future-card>span:last-of-type { font-family: var(--font-head); font-size: 0.95rem; font-weight: 700; }
.future-card p { font-size: 0.82rem; color: var(--text-muted); margin-bottom: 0; }
.future-cta { font-size: 0.72rem; font-weight: 800; letter-spacing: 0.08em; color: var(--accent2); margin-top: 0.4rem; text-transform: uppercase; }

/* ─── IMPACT ─── */
.impact-pillars { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.2rem; max-width: 750px; margin: 2rem auto 0; }

.pillar {
    padding: 1.8rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 18px;
    text-align: center;
    transition: all var(--transition);
}

.pillar:hover { transform: translateY(-4px); border-color: var(--accent); box-shadow: var(--shadow-lg); }
.pillar-icon { font-size: 2.2rem; margin-bottom: 0.8rem; display: block; }
.pillar h3 { font-size: 1rem; margin-bottom: 0.3rem; }
.pillar p { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 0; }

.impact-statement {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto 1rem;
    line-height: 1.8;
    text-align: center;
    letter-spacing: 0.02em;
}

/* ─── CONTACT ─── */
.contact-form { display: flex; flex-direction: column; gap: 0.8rem; max-width: 500px; margin: 0 auto; }

.form-input {
    width: 100%;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-family: var(--font-body);
    font-size: 0.95rem;
    padding: 0.85rem 1rem;
    outline: none;
    transition: border-color var(--transition);
    letter-spacing: 0.02em;
}

.form-input:focus { border-color: var(--accent); box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.08); }
.form-input::placeholder { color: var(--text-muted); }

.form-textarea { resize: vertical; min-height: 110px; }
.form-note { font-size: 0.85rem; color: var(--success); min-height: 1.3em; text-align: center; }

/* ─── FOOTER ─── */
.footer { padding: 1.5rem 0; background: var(--surface); border-top: 2px solid var(--border); }

.footer-inner {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.5rem;
    font-size: 0.82rem;
    color: var(--text-muted);
    letter-spacing: 0.02em;
}

.footer-logo { font-family: var(--font-head); font-weight: 700; color: var(--text); }

/* ─── TOAST ───
.toast {
    position: fixed;
    bottom: 1.5rem;
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    background: var(--text);
    color: #fff;
    padding: 0.7rem 1.5rem;
    border-radius: 100px;
    font-size: 0.88rem;
    font-weight: 600;
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
    z-index: 9999;
    box-shadow: var(--shadow-lg);
    letter-spacing: 0.03em;
}

.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ─── ADHD FOCUS MODE ─── */
body.adhf-focus {
    --bg: #1a1a1a;
    --bg2: #2a2a2a;
    --surface: #242424;
    --border: #404040;
}

body.adhf-focus * {
    letter-spacing: 0.05em !important;
    line-height: 1.9 !important;
}

body.adhf-focus .input-wrap,
body.adhf-focus .output-wrap,
body.adhf-focus .tab-panel {
    padding: 2rem !important;
    margin: 1.5rem 0 !important;
}

body.adhf-focus .tab-panel p {
    margin-bottom: 1.5rem !important;
    font-size: 1.05rem !important;
}

body.adhf-focus .tab-panel ol {
    margin-bottom: 1.5rem !important;
}

body.adhf-focus .term-card,
body.adhf-focus .quiz-q {
    margin-bottom: 1.2rem !important;
    padding: 1.2rem !important;
    border-width: 3px !important;
}

body.adhf-focus .quiz-option {
    padding: 1rem !important;
    margin-bottom: 0.8rem !important;
    font-size: 1rem !important;
}

body.adhf-focus .level-cards,
body.adhf-focus .subject-selector {
    opacity: 0.5 !important;
    pointer-events: none !important;
}

body.adhf-focus .nav-links,
body.adhf-focus .features-grid {
    display: none !important;
}

/* ─── FORMULA CARD ─── */
.formula-card {
    padding: 1.2rem;
    margin-bottom: 1rem;
    background: var(--accent-soft);
    border-left: 5px solid var(--accent);
    border-radius: var(--radius-sm);
    border-right: 1px solid var(--border);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
}

.formula-card strong {
    color: var(--accent2);
    font-family: 'Courier New', monospace;
    font-size: 1.1rem;
    display: block;
    margin-bottom: 0.5rem;
}

.formula-card p {
    font-size: 0.95rem;
    color: var(--text);
    margin: 0;
}

/* ─── RESPONSIVE ─── */
@media (max-width: 1024px) {
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .comparison-cards { grid-template-columns: repeat(2, 1fr); }
    .step-connector { display: none; }
    .steps-row { gap: 1rem; }
    .tool-card { grid-template-columns: 1fr; }
    .flashcard-layout { grid-template-columns: 1fr; }
    .quiz-layout { grid-template-columns: 1fr; }
    .stat-row { grid-template-columns: repeat(2, 1fr); }
    .panel-row { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
    .hero .container { grid-template-columns: 1fr; gap: 1.5rem; }
    .hero-right { min-height: 280px; order: -1; }
    .formula-card { width: 240px; padding: 1.5rem; }
    .about-grid { grid-template-columns: 1fr; }
    .showcase-grid { grid-template-columns: 1fr; }
    .testimonials-grid { grid-template-columns: 1fr; }
    .future-grid { grid-template-columns: repeat(2, 1fr); }
    .impact-pillars { grid-template-columns: 1fr; }
    .comparison-cards { grid-template-columns: 1fr 1fr; }
    .nav-links { display: none; }
    .nav-cta { display: none; }
    .hamburger { display: flex; }
    .nav-links.open {
        display: flex;
        flex-direction: column;
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--surface);
        padding: 1rem;
        border-bottom: 2px solid var(--border);
        z-index: 998;
        box-shadow: var(--shadow-lg);
    }
    .nav-links.open .nav-cta-mobile { display: inline-flex; margin-top: 0.5rem; width: fit-content; }
    .footer-inner { flex-direction: column; text-align: center; }
    .comparison-table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
    .comparison-table { min-width: 650px; }
}

@media (max-width: 520px) {
    .level-cards { gap: 0.5rem; }
    .level-card { min-width: 120px; padding: 1rem 0.8rem; }
    .future-grid { grid-template-columns: 1fr; }
    .stats-grid { grid-template-columns: 1fr; }
    .features-grid { grid-template-columns: 1fr; }
    .comparison-cards { grid-template-columns: 1fr; }
    .steps-row { flex-direction: column; }
    .step-card { min-width: auto; }
    .subject-btn { padding: 0.7rem 1.5rem; font-size: 0.9rem; }
}

/* Google Translate Styling */
#google_translate_element .goog-te-gadget {
    font-family: var(--font-body) !important;
}

#google_translate_element .goog-te-gadget-simple {
    background: var(--surface) !important;
    border: 2px solid var(--border) !important;
    border-radius: 8px !important;
    padding: 0.4rem 0.8rem !important;
    font-size: 0.9rem !important;
}

#google_translate_element .goog-te-gadget-simple img {
    display: none !important;
}

#google_translate_element .goog-te-gadget-simple span {
    color: var(--text) !important;
}

.goog-te-banner-frame.skiptranslate {
    display: none !important;
}

body {
    top: 0px !important;
    position: static !important;
}

iframe.goog-te-banner-frame {
    display: none !important;
}
.goog-te-banner-frame { display: none !important; }
body { top: 0 !important; }
.goog-te-gadget-simple { border-radius: 8px !important; border: 2px solid var(--border) !important; }
.goog-te-gadget-simple img { display: none !important; }