/* ========================================
   RESET & BASE
   ======================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-primary: #08080f;
    --bg-secondary: #0d0d1a;
    --bg-card: rgba(255, 255, 255, 0.02);
    --border-subtle: rgba(255, 255, 255, 0.05);
    --text-primary: #f0f0f8;
    --text-secondary: #8888aa;
    --text-muted: #4a4a6a;
    --accent: #e94560;
    --accent-dim: rgba(233, 69, 96, 0.08);
    --accent-glow: rgba(233, 69, 96, 0.2);
    --success: #4ade80;
    --success-dim: rgba(74, 222, 128, 0.06);
    --warning: #f5c842;
    --radius: 14px;
    --radius-lg: 24px;
    --transition: 0.4s cubic-bezier(0.22, 1, 0.36, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* ========================================
   BACKGROUND
   ======================================== */
.app {
    position: relative;
    width: 100%;
    max-width: 820px;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px 0;
}

.bg-orb {
    position: fixed;
    border-radius: 50%;
    filter: blur(160px);
    pointer-events: none;
    opacity: 0.06;
    z-index: 0;
}

.orb-1 {
    width: 600px;
    height: 600px;
    background: #e94560;
    top: -200px;
    right: -200px;
    opacity: 0.04;
}

.orb-2 {
    width: 500px;
    height: 500px;
    background: #4a6cf7;
    bottom: -150px;
    left: -150px;
    opacity: 0.03;
}

.orb-3 {
    width: 400px;
    height: 400px;
    background: #f5c842;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0.02;
}

.bg-grid {
    position: fixed;
    inset: 0;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.006) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.006) 1px, transparent 1px);
    background-size: 52px 52px;
    pointer-events: none;
    z-index: 0;
}

/* ========================================
   CONTAINER
   ======================================== */
.container {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 780px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 44px 48px;
    backdrop-filter: blur(60px);
    box-shadow: 
        0 40px 120px rgba(0, 0, 0, 0.5),
        inset 0 1px 0 rgba(255, 255, 255, 0.03);
    animation: containerIn 0.8s cubic-bezier(0.22, 1, 0.36, 1);
}

@keyframes containerIn {
    from {
        opacity: 0;
        transform: translateY(30px) scale(0.97);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

/* ========================================
   HEADER
   ======================================== */
.header {
    text-align: center;
    margin-bottom: 36px;
    position: relative;
}

.header::after {
    content: '';
    position: absolute;
    bottom: -18px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    border-radius: 2px;
}

.header-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 14px;
}

.brand-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--accent);
    box-shadow: 0 0 30px var(--accent-glow);
    animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(0.8); }
}

.brand-text {
    font-size: 0.6rem;
    font-weight: 700;
    letter-spacing: 4px;
    text-transform: uppercase;
    color: var(--text-secondary);
    opacity: 0.6;
}

.header h1 {
    font-size: 2.4rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    background: linear-gradient(135deg, #ffffff 35%, #8888bb);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
}

.header h1 span {
    background: linear-gradient(135deg, var(--accent), #ff6b8a);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 400;
    margin-top: 4px;
    letter-spacing: 0.5px;
}

/* ========================================
   AUTH SECTION
   ======================================== */
.auth-section {
    padding: 20px 0 30px 0;
    animation: fadeUp 0.7s ease-out 0.2s both;
}

@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(16px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.auth-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius);
    padding: 40px 32px;
    max-width: 400px;
    margin: 0 auto;
    text-align: center;
    transition: all var(--transition);
}

.auth-card:hover {
    border-color: rgba(255, 255, 255, 0.06);
}

.auth-card .shake {
    animation: authShake 0.5s ease-out;
}

@keyframes authShake {
    0%, 100% { transform: translateX(0); }
    15% { transform: translateX(-12px); }
    30% { transform: translateX(12px); }
    45% { transform: translateX(-8px); }
    60% { transform: translateX(8px); }
    80% { transform: translateX(-4px); }
}

.auth-icon {
    width: 56px;
    height: 56px;
    margin: 0 auto 14px;
    border-radius: 50%;
    background: var(--accent-dim);
    border: 1px solid rgba(233, 69, 96, 0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent);
    transition: all var(--transition);
}

.auth-card:hover .auth-icon {
    transform: scale(1.05);
    box-shadow: 0 0 40px var(--accent-glow);
}

.auth-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 4px;
}

.auth-desc {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 26px;
    font-weight: 400;
}

.auth-form {
    text-align: left;
}

.auth-error {
    font-size: 0.8rem;
    color: #e94560;
    background: rgba(233, 69, 96, 0.08);
    padding: 10px 14px;
    border-radius: 8px;
    border: 1px solid rgba(233, 69, 96, 0.12);
    margin-bottom: 16px;
    display: none;
    animation: fadeUp 0.3s ease-out;
}

.auth-error.visible {
    display: block;
}

/* ========================================
   LOGIN SECTION
   ======================================== */
.login-section {
    padding: 10px 0 18px 0;
    animation: fadeUp 0.7s ease-out 0.2s both;
    display: none;
}

.login-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius);
    padding: 36px 32px;
    max-width: 500px;
    margin: 0 auto;
    text-align: center;
    transition: all var(--transition);
}

.login-card:hover {
    border-color: rgba(255, 255, 255, 0.06);
}

.login-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 14px;
    border-radius: 50%;
    background: var(--accent-dim);
    border: 1px solid rgba(233, 69, 96, 0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent);
    transition: all var(--transition);
}

.login-card:hover .login-icon {
    transform: scale(1.05);
    box-shadow: 0 0 40px var(--accent-glow);
}

.login-icon svg {
    width: 28px;
    height: 28px;
}

.login-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 4px;
}

.login-desc {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 26px;
    font-weight: 400;
}

/* ========================================
   FORM
   ======================================== */
.form-section {
    margin-bottom: 18px;
}

.form-section-title {
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 12px;
    text-align: center;
    opacity: 0.6;
}

.form-divider {
    height: 1px;
    background: var(--border-subtle);
    margin: 16px 0 18px 0;
}

.form-group {
    text-align: left;
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 6px;
    text-transform: uppercase;
    letter-spacing: 0.8px;
}

.form-input {
    width: 100%;
    padding: 13px 18px;
    border-radius: 10px;
    border: 1.5px solid var(--border-subtle);
    background: rgba(0, 0, 0, 0.25);
    color: #fff;
    font-family: 'Inter', sans-serif;
    font-size: 0.95rem;
    outline: none;
    transition: all var(--transition);
}

.form-input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 4px var(--accent-dim);
    background: rgba(0, 0, 0, 0.35);
}

.form-input::placeholder {
    color: var(--text-muted);
    font-weight: 300;
}

.form-hint {
    display: block;
    font-size: 0.65rem;
    color: var(--text-secondary);
    opacity: 0.4;
    margin-top: 5px;
    font-weight: 400;
}

.btn-primary {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
    margin-top: 8px;
    padding: 15px;
    border: none;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), #d63851);
    color: #fff;
    font-family: 'Inter', sans-serif;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent, rgba(255, 255, 255, 0.05));
    opacity: 0;
    transition: opacity var(--transition);
}

.btn-primary:hover::before {
    opacity: 1;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 16px 48px rgba(233, 69, 96, 0.25);
}

.btn-primary:active {
    transform: scale(0.97);
}

.btn-primary svg {
    transition: transform var(--transition);
}

.btn-primary:hover svg {
    transform: translateX(4px);
}

/* ========================================
   QUIZ
   ======================================== */
.quiz-wrapper {
    animation: fadeUp 0.6s ease-out;
    display: none;
}

.stats-bar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0;
    background: var(--bg-card);
    border-radius: 12px;
    padding: 4px;
    margin-bottom: 28px;
    border: 1px solid var(--border-subtle);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 18px;
    flex: 1;
    justify-content: center;
    border-radius: 8px;
    transition: all var(--transition);
}

.stat-item:hover {
    background: rgba(255, 255, 255, 0.02);
}

.stat-label {
    font-size: 0.55rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.stat-value {
    font-size: 0.95rem;
    font-weight: 700;
    color: #fff;
    min-width: 30px;
    text-align: center;
    transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.stat-value.pop {
    animation: pop 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes pop {
    0% { transform: scale(1); }
    40% { transform: scale(1.25); }
    70% { transform: scale(0.95); }
    100% { transform: scale(1); }
}

.stat-value#score-display {
    color: var(--accent);
}
.stat-value#mistakes-display {
    color: var(--warning);
}

.stat-divider {
    width: 1px;
    height: 28px;
    background: var(--border-subtle);
}

.status-active { color: #4ade80; }
.status-correct { color: #4ade80; }
.status-wrong { color: #e94560; }
.status-failed { color: #e94560; }

.progress-track {
    width: 100%;
    height: 3px;
    background: var(--border-subtle);
    border-radius: 4px;
    margin-bottom: 22px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent), #ff6b8a);
    border-radius: 4px;
    transition: width 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}

.progress-bar.failed {
    background: linear-gradient(90deg, #e94560, #ff3333);
}

.question-meta {
    margin-bottom: 8px;
}

.question-number {
    font-size: 0.6rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 2px;
    opacity: 0.6;
}

.question-text {
    font-size: 1.3rem;
    font-weight: 600;
    line-height: 1.7;
    margin-bottom: 18px;
    color: #f5f5fa;
    min-height: 55px;
    animation: slideUp 0.5s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.partial-toggle {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 16px;
    padding: 10px 16px;
    background: rgba(255, 255, 255, 0.02);
    border-radius: 10px;
    border: 1px solid var(--border-subtle);
    flex-wrap: wrap;
}

.partial-btn {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 18px;
    border: 1.5px solid var(--border-subtle);
    border-radius: 8px;
    background: transparent;
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
}

.partial-btn:hover {
    border-color: rgba(255, 255, 255, 0.15);
    background: rgba(255, 255, 255, 0.02);
}

.partial-btn.active {
    border-color: var(--warning);
    background: var(--warning-dim);
    color: var(--warning);
}

.partial-btn.active .partial-indicator {
    background: var(--warning);
    box-shadow: 0 0 20px rgba(245, 200, 66, 0.2);
}

.partial-indicator {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-secondary);
    transition: all var(--transition);
}

.partial-hint {
    font-size: 0.7rem;
    color: var(--text-secondary);
    opacity: 0.4;
}

.answer-reveal {
    background: var(--success-dim);
    border: 1px solid rgba(74, 222, 128, 0.08);
    border-radius: 10px;
    padding: 12px 18px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 14px;
    animation: fadeUp 0.4s ease-out;
}

.answer-label {
    font-size: 0.5rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--success);
    background: rgba(74, 222, 128, 0.08);
    padding: 3px 14px;
    border-radius: 100px;
    white-space: nowrap;
}

.answer-text {
    font-size: 0.9rem;
    font-weight: 500;
    color: #d0d0dd;
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-bottom: 22px;
}

.option-btn {
    padding: 15px 20px;
    border: 1.5px solid var(--border-subtle);
    border-radius: 10px;
    background: var(--bg-card);
    color: #d0d0dd;
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    font-weight: 400;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
    text-align: left;
    line-height: 1.4;
    position: relative;
}

.option-btn::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 10px;
    background: linear-gradient(135deg, rgba(233, 69, 96, 0.02), transparent);
    opacity: 0;
    transition: opacity var(--transition);
}

.option-btn:hover:not(:disabled)::before {
    opacity: 1;
}

.option-btn:hover:not(:disabled) {
    border-color: rgba(233, 69, 96, 0.2);
    background: rgba(255, 255, 255, 0.02);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.15);
}

.option-btn:active:not(:disabled) {
    transform: scale(0.97);
}

.option-btn:disabled {
    cursor: default;
    opacity: 0.35;
}

.option-btn .option-letter {
    display: inline-block;
    width: 26px;
    height: 26px;
    line-height: 26px;
    text-align: center;
    border-radius: 6px;
    background: rgba(255, 255, 255, 0.03);
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--text-secondary);
    margin-right: 12px;
    transition: all var(--transition);
}

.option-btn.selected {
    border-color: var(--accent);
    background: var(--accent-dim);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(233, 69, 96, 0.05);
}

.option-btn.selected .option-letter {
    background: rgba(233, 69, 96, 0.12);
    color: var(--accent);
}

.option-btn.selected-correct {
    border-color: var(--success);
    background: var(--success-dim);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(74, 222, 128, 0.05);
    animation: correctSelect 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes correctSelect {
    0% { transform: scale(1) translateY(0); }
    40% { transform: scale(1.06) translateY(-4px); }
    70% { transform: scale(0.98) translateY(-2px); }
    100% { transform: scale(1) translateY(-2px); }
}

.option-btn.selected-correct .option-letter {
    background: rgba(74, 222, 128, 0.1);
    color: var(--success);
}

.option-btn.selected-wrong {
    border-color: var(--accent);
    background: rgba(233, 69, 96, 0.04);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(233, 69, 96, 0.05);
    animation: wrongSelect 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes wrongSelect {
    0% { transform: scale(1) translateY(0); }
    40% { transform: scale(1.06) translateY(-4px); }
    70% { transform: scale(0.98) translateY(-2px); }
    100% { transform: scale(1) translateY(-2px); }
}

.option-btn.selected-wrong .option-letter {
    background: rgba(233, 69, 96, 0.1);
    color: var(--accent);
}

.option-btn.show-correct {
    border-color: var(--success);
    background: var(--success-dim);
}

.option-btn.show-correct .option-letter {
    background: rgba(74, 222, 128, 0.08);
    color: var(--success);
}

.btn-next {
    display: none;
    align-items: center;
    justify-content: center;
    gap: 12px;
    width: 100%;
    padding: 15px;
    border: none;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), #d63851);
    color: #fff;
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    margin-top: 4px;
    position: relative;
    overflow: hidden;
}

.btn-next::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent, rgba(255, 255, 255, 0.05));
    opacity: 0;
    transition: opacity var(--transition);
}

.btn-next:hover::before {
    opacity: 1;
}

.btn-next.visible {
    display: flex;
    animation: fadeUp 0.4s ease-out;
}

.btn-next:hover {
    transform: translateY(-3px);
    box-shadow: 0 16px 48px rgba(233, 69, 96, 0.2);
}

.btn-next:active {
    transform: scale(0.97);
}

.btn-next svg {
    transition: transform var(--transition);
}

.btn-next:hover svg {
    transform: translateX(4px);
}

/* ========================================
   RESULTS
   ======================================== */
.results-container {
    text-align: center;
    padding: 20px 0;
    animation: fadeUp 0.6s ease-out;
}

.results-icon {
    font-size: 4rem;
    margin-bottom: 12px;
    display: block;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

.results-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.results-score {
    font-size: 4.5rem;
    font-weight: 800;
    margin: 8px 0;
    letter-spacing: -2px;
}

.results-percentage {
    font-size: 1.2rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 14px;
}

.results-message {
    font-size: 1rem;
    padding: 16px 22px;
    background: var(--bg-card);
    border-radius: 10px;
    margin: 14px 0 22px 0;
    border: 1px solid var(--border-subtle);
    line-height: 1.7;
}

.results-stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin: 18px 0;
    flex-wrap: wrap;
}

.results-stats .stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
}

.results-stats .stat-value {
    font-size: 1.6rem;
    font-weight: 700;
}

.results-stats .stat-label {
    font-size: 0.6rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.results-review {
    margin-top: 32px;
    text-align: left;
    max-height: 420px;
    overflow-y: auto;
    padding-right: 4px;
}

.results-review::-webkit-scrollbar {
    width: 4px;
}
.results-review::-webkit-scrollbar-track {
    background: var(--bg-card);
    border-radius: 4px;
}
.results-review::-webkit-scrollbar-thumb {
    background: rgba(233, 69, 96, 0.2);
    border-radius: 4px;
}

.review-title {
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 14px;
    text-align: center;
    opacity: 0.6;
}

.review-item {
    background: var(--bg-card);
    padding: 14px 18px;
    margin-bottom: 6px;
    border-radius: 8px;
    border-left: 2px solid rgba(233, 69, 96, 0.12);
    transition: all var(--transition);
}

.review-item:hover {
    background: rgba(255, 255, 255, 0.02);
}

.review-item .rq {
    font-size: 0.85rem;
    color: #d0d0dd;
    margin-bottom: 4px;
}
.review-item .rc {
    font-size: 0.8rem;
    color: var(--success);
    margin-left: 14px;
}
.review-item .rw {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-left: 14px;
    opacity: 0.4;
}

.btn-restart {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 15px 40px;
    border: none;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--success), #2ecc71);
    color: #fff;
    font-family: 'Inter', sans-serif;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    margin-top: 16px;
}

.btn-restart:hover {
    transform: translateY(-3px);
    box-shadow: 0 16px 48px rgba(74, 222, 128, 0.2);
}

.btn-restart:active {
    transform: scale(0.97);
}

.results-failed .results-title { color: var(--accent); }
.results-failed .results-score { color: var(--accent); }
.results-failed .results-message { border-color: rgba(233, 69, 96, 0.08); }
.results-passed .results-title { color: var(--success); }
.results-passed .results-score { color: var(--success); }

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    15% { transform: translateX(-10px); }
    30% { transform: translateX(10px); }
    45% { transform: translateX(-6px); }
    60% { transform: translateX(6px); }
    80% { transform: translateX(-3px); }
}
.shake { animation: shake 0.5s ease-out; }

/* ========================================
   FOOTER
   ======================================== */
.footer {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--border-subtle);
    text-align: center;
}

.footer-brand {
    color: var(--text-secondary);
    font-size: 0.65rem;
    font-weight: 500;
    letter-spacing: 2px;
    text-transform: uppercase;
    opacity: 0.5;
    margin-bottom: 6px;
}

.footer-credit {
    color: var(--text-secondary);
    font-size: 0.7rem;
    font-weight: 400;
    letter-spacing: 0.5px;
    opacity: 0.35;
    transition: all var(--transition);
}

.footer-credit span {
    color: var(--accent);
    font-weight: 600;
    opacity: 0.7;
    transition: all var(--transition);
    position: relative;
}

.footer-credit span::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--accent);
    transition: width var(--transition);
}

.footer-credit:hover span::after {
    width: 100%;
}

.footer-credit:hover {
    opacity: 0.8;
}

.footer-credit:hover span {
    opacity: 1;
}

/* ========================================
   RESPONSIVE
   ======================================== */
@media (max-width: 700px) {
    .container { padding: 28px 24px; border-radius: 20px; }
    .header h1 { font-size: 1.8rem; }
    .options-grid { grid-template-columns: 1fr; }
    .question-text { font-size: 1.1rem; }
    .answer-reveal { flex-direction: column; align-items: flex-start; gap: 6px; }
    .stats-bar { flex-wrap: wrap; gap: 2px; padding: 6px 4px; }
    .stat-item { padding: 4px 10px; flex: 1 1 30%; }
    .stat-divider { display: none; }
    .results-score { font-size: 3.2rem; }
    .results-stats { gap: 20px; }
    .login-card { padding: 28px 20px; }
    .auth-card { padding: 28px 20px; }
    .partial-toggle { flex-direction: column; align-items: stretch; gap: 8px; }
}

@media (max-width: 420px) {
    .container { padding: 18px 16px; border-radius: 16px; }
    .header h1 { font-size: 1.4rem; }
    .stat-item { font-size: 0.65rem; padding: 4px 6px; }
    .stat-value { font-size: 0.8rem; }
    .question-text { font-size: 0.95rem; }
    .option-btn { font-size: 0.8rem; padding: 12px 14px; }
    .answer-text { font-size: 0.8rem; }
    .login-card h3 { font-size: 1rem; }
    .auth-card h3 { font-size: 1rem; }
    .results-score { font-size: 2.8rem; }
}