/* ============================================
   VocStu – Modern Vocabulary Learning CSS
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

/* ---------- CSS Custom Properties ---------- */
:root {
    --primary: #6C5CE7;
    --primary-light: #a29bfe;
    --primary-dark: #4834d4;
    --accent: #00cec9;
    --accent-light: #81ecec;
    --success: #00b894;
    --danger: #e17055;
    --danger-light: #fab1a0;
    --warning: #fdcb6e;
    --bg-body: #0f0f1a;
    --bg-card: rgba(255, 255, 255, 0.05);
    --bg-card-hover: rgba(255, 255, 255, 0.08);
    --bg-glass: rgba(255, 255, 255, 0.07);
    --border-glass: rgba(255, 255, 255, 0.12);
    --text-primary: #f5f5f5;
    --text-secondary: #b2bec3;
    --text-muted: #636e72;
    --radius: 16px;
    --radius-sm: 10px;
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.45);
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

/* ---------- Global Styles ---------- */
*, *::before, *::after {
    box-sizing: border-box;
}

html {
    font-size: 16px;
    position: relative;
    min-height: 100%;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font);
    background: var(--bg-body);
    color: var(--text-primary);
    margin-bottom: 80px;
    overflow-x: hidden;
}

/* Animated gradient background */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background:
        radial-gradient(ellipse 600px 600px at 20% 20%, rgba(108, 92, 231, 0.15), transparent),
        radial-gradient(ellipse 500px 500px at 80% 80%, rgba(0, 206, 201, 0.1), transparent),
        radial-gradient(ellipse 400px 400px at 50% 50%, rgba(108, 92, 231, 0.05), transparent);
    z-index: -1;
    animation: bgShift 20s ease-in-out infinite alternate;
}

@keyframes bgShift {
    0% { opacity: 1; }
    50% { opacity: 0.7; }
    100% { opacity: 1; }
}

a {
    color: var(--primary-light);
    text-decoration: none;
    transition: var(--transition);
}
a:hover {
    color: var(--accent-light);
}

/* ---------- Navbar ---------- */
.navbar {
    background: rgba(15, 15, 26, 0.85) !important;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-glass) !important;
    padding: 0.8rem 0;
    box-shadow: none !important;
}

.navbar-brand {
    font-weight: 800;
    font-size: 1.4rem;
    background: linear-gradient(135deg, var(--primary-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
}

.navbar .nav-link {
    color: var(--text-secondary) !important;
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.5rem 1rem !important;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    position: relative;
}
.navbar .nav-link:hover,
.navbar .nav-link.active {
    color: var(--text-primary) !important;
    background: var(--bg-glass);
}

.navbar-toggler {
    border-color: var(--border-glass);
}
.navbar-toggler-icon {
    filter: invert(1);
}

/* ---------- Glass Card ---------- */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
}
.glass-card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* ---------- Buttons ---------- */
.btn-vocstudy {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.65rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.btn-vocstudy.primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    box-shadow: 0 4px 15px rgba(108, 92, 231, 0.4);
}
.btn-vocstudy.primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(108, 92, 231, 0.55);
    color: #fff;
}

.btn-vocstudy.accent {
    background: linear-gradient(135deg, var(--accent), #00b894);
    color: #fff;
    box-shadow: 0 4px 15px rgba(0, 206, 201, 0.35);
}
.btn-vocstudy.accent:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(0, 206, 201, 0.5);
    color: #fff;
}

.btn-vocstudy.danger {
    background: linear-gradient(135deg, var(--danger), #d63031);
    color: #fff;
    box-shadow: 0 4px 15px rgba(225, 112, 85, 0.35);
}
.btn-vocstudy.danger:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(225, 112, 85, 0.5);
    color: #fff;
}

.btn-vocstudy.outline {
    background: transparent;
    color: var(--primary-light);
    border: 1.5px solid var(--primary-light);
}
.btn-vocstudy.outline:hover {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.btn-vocstudy.ghost {
    background: var(--bg-glass);
    color: var(--text-secondary);
    border: 1px solid var(--border-glass);
}
.btn-vocstudy.ghost:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
}

/* ---------- Forms ---------- */
.form-vocstudy .form-control,
.form-vocstudy .form-select {
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    padding: 0.7rem 1rem;
    font-size: 0.95rem;
    transition: var(--transition);
}
.form-vocstudy .form-control:focus,
.form-vocstudy .form-select:focus {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(108, 92, 231, 0.25);
    color: var(--text-primary);
}
.form-vocstudy .form-control::placeholder {
    color: var(--text-muted);
}
.form-vocstudy label {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
    margin-bottom: 0.4rem;
}

/* ---------- Tables ---------- */
.table-vocstudy {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0 0.5rem;
}
.table-vocstudy thead th {
    background: transparent;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    padding: 0.7rem 1rem;
    border: none;
}
.table-vocstudy tbody tr {
    background: var(--bg-card);
    border-radius: var(--radius-sm);
    transition: var(--transition);
}
.table-vocstudy tbody tr:hover {
    background: var(--bg-card-hover);
    transform: scale(1.005);
}
.table-vocstudy td {
    padding: 0.9rem 1rem;
    border: none;
    vertical-align: middle;
    color: var(--text-primary);
}
.table-vocstudy td:first-child {
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}
.table-vocstudy td:last-child {
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

/* ---------- Stat Cards ---------- */
.stat-card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}
.stat-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: var(--radius) var(--radius) 0 0;
}
.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}
.stat-card .stat-value {
    font-size: 2.2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.stat-card .stat-label {
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 500;
    margin-top: 0.3rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* ---------- Mode Cards (Dashboard) ---------- */
.mode-card {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    text-decoration: none;
    color: var(--text-primary);
    display: block;
}
.mode-card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
    color: var(--text-primary);
}
.mode-card .mode-icon {
    font-size: 2.5rem;
    margin-bottom: 0.8rem;
    display: block;
}
.mode-card .mode-title {
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 0.4rem;
}
.mode-card .mode-desc {
    color: var(--text-muted);
    font-size: 0.85rem;
    line-height: 1.5;
}

/* ---------- Learning Section ---------- */
.learn-container {
    max-width: 700px;
    margin: 0 auto;
}

.flashcard {
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    min-height: 220px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.flashcard .word-display {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.flashcard .word-sub {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.flashcard .progress-bar-custom {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 0 0 var(--radius) var(--radius);
    transition: width 0.5s ease;
}

/* ---------- Multiple Choice ---------- */
.choice-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-top: 1.5rem;
}

.choice-btn {
    background: var(--bg-card);
    border: 1.5px solid var(--border-glass);
    border-radius: var(--radius-sm);
    padding: 1rem 1.2rem;
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}
.choice-btn:hover {
    border-color: var(--primary-light);
    background: rgba(108, 92, 231, 0.1);
    transform: scale(1.03);
}
.choice-btn.correct {
    border-color: var(--success);
    background: rgba(0, 184, 148, 0.15);
    animation: pulseCorrect 0.5s ease;
}
.choice-btn.incorrect {
    border-color: var(--danger);
    background: rgba(225, 112, 85, 0.15);
    animation: shakeWrong 0.5s ease;
}
.choice-btn.highlight-answer {
    border-color: var(--success);
    background: rgba(0, 184, 148, 0.25);
    box-shadow: 0 0 15px rgba(0, 184, 148, 0.3);
}

/* ---------- Match Pair ---------- */
.match-columns {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.match-item {
    background: var(--bg-card);
    border: 1.5px solid var(--border-glass);
    border-radius: var(--radius-sm);
    padding: 0.9rem 1.2rem;
    margin-bottom: 0.7rem;
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    user-select: none;
}
.match-item:hover {
    border-color: var(--primary-light);
    background: rgba(108, 92, 231, 0.1);
}
.match-item.selected {
    border-color: var(--primary);
    background: rgba(108, 92, 231, 0.2);
    box-shadow: 0 0 12px rgba(108, 92, 231, 0.3);
}
.match-item.matched {
    border-color: var(--success);
    background: rgba(0, 184, 148, 0.12);
    opacity: 0.7;
    pointer-events: none;
}
.match-item.wrong {
    border-color: var(--danger);
    background: rgba(225, 112, 85, 0.12);
    animation: shakeWrong 0.5s ease;
}

/* ---------- Typing Mode ---------- */
.typing-input {
    background: rgba(255, 255, 255, 0.06);
    border: 2px solid var(--border-glass);
    border-radius: var(--radius-sm);
    padding: 1rem 1.3rem;
    font-size: 1.2rem;
    font-weight: 500;
    color: var(--text-primary);
    width: 100%;
    text-align: center;
    transition: var(--transition);
    font-family: var(--font);
}
.typing-input:focus {
    outline: none;
    border-color: var(--primary-light);
    background: rgba(255, 255, 255, 0.1);
    box-shadow: 0 0 0 4px rgba(108, 92, 231, 0.2);
}
.typing-input.correct {
    border-color: var(--success);
    box-shadow: 0 0 0 4px rgba(0, 184, 148, 0.2);
}
.typing-input.incorrect {
    border-color: var(--danger);
    box-shadow: 0 0 0 4px rgba(225, 112, 85, 0.2);
    animation: shakeWrong 0.5s ease;
}

/* ---------- Progress Ring ---------- */
.progress-ring-container {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}
.progress-ring-text {
    position: absolute;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
}

/* ---------- Score Summary ---------- */
.score-summary {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 2.5rem;
    text-align: center;
}
.score-summary .score-big {
    font-size: 4rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.score-summary .score-label {
    color: var(--text-muted);
    font-size: 1.1rem;
    margin-top: 0.3rem;
}

/* ---------- Badge / Tag ---------- */
.badge-status {
    display: inline-block;
    padding: 0.25rem 0.7rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.3px;
}
.badge-status.mastered {
    background: rgba(0, 184, 148, 0.2);
    color: var(--success);
}
.badge-status.learning {
    background: rgba(108, 92, 231, 0.2);
    color: var(--primary-light);
}
.badge-status.weak {
    background: rgba(225, 112, 85, 0.2);
    color: var(--danger);
}

/* ---------- Footer ---------- */
.footer {
    background: rgba(15, 15, 26, 0.9);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--border-glass) !important;
    color: var(--text-muted);
    position: absolute;
    bottom: 0;
    width: 100%;
    white-space: nowrap;
    line-height: 60px;
}
.footer a {
    color: var(--primary-light);
}

/* ---------- Animations ---------- */
@keyframes pulseCorrect {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

@keyframes shakeWrong {
    0%, 100% { transform: translateX(0); }
    15% { transform: translateX(-8px); }
    30% { transform: translateX(8px); }
    45% { transform: translateX(-6px); }
    60% { transform: translateX(6px); }
    75% { transform: translateX(-3px); }
    90% { transform: translateX(3px); }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.animate-fadeInUp {
    animation: fadeInUp 0.5s ease forwards;
}

.animate-slideIn {
    animation: slideIn 0.4s ease forwards;
}

/* Stagger animation delays */
.stagger-1 { animation-delay: 0.05s; opacity: 0; }
.stagger-2 { animation-delay: 0.1s; opacity: 0; }
.stagger-3 { animation-delay: 0.15s; opacity: 0; }
.stagger-4 { animation-delay: 0.2s; opacity: 0; }
.stagger-5 { animation-delay: 0.25s; opacity: 0; }
.stagger-6 { animation-delay: 0.3s; opacity: 0; }

/* ---------- Identity Pages Override ---------- */
.identity-override input[type="text"],
.identity-override input[type="email"],
.identity-override input[type="password"] {
    background: rgba(255, 255, 255, 0.06) !important;
    border: 1px solid var(--border-glass) !important;
    border-radius: var(--radius-sm) !important;
    color: var(--text-primary) !important;
    padding: 0.7rem 1rem !important;
}
.identity-override input:focus {
    border-color: var(--primary-light) !important;
    box-shadow: 0 0 0 3px rgba(108, 92, 231, 0.25) !important;
}
.identity-override label {
    color: var(--text-secondary) !important;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
    .choice-grid {
        grid-template-columns: 1fr;
    }
    .match-columns {
        grid-template-columns: 1fr 1fr;
        gap: 0.8rem;
    }
    .match-item {
        padding: 0.6rem 0.5rem;
        font-size: 0.85rem;
    }
    .glass-card {
        padding: 1.5rem;
    }
    .flashcard {
        padding: 2rem 1.5rem;
        min-height: 180px;
    }
    .flashcard .word-display {
        font-size: 1.5rem;
    }
    .stat-card .stat-value {
        font-size: 1.8rem;
    }
    .toast-vocstudy {
        max-width: 90%;
        right: 5%;
        left: 5%;
    }
}

/* ---------- Scrollbar ---------- */
::-webkit-scrollbar {
    width: 6px;
}
::-webkit-scrollbar-track {
    background: var(--bg-body);
}
::-webkit-scrollbar-thumb {
    background: var(--border-glass);
    border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--primary);
}

/* ---------- Selection ---------- */
::selection {
    background: rgba(108, 92, 231, 0.4);
    color: #fff;
}

/* ---------- Utility ---------- */
.text-gradient {
    background: linear-gradient(135deg, var(--primary-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-title {
    font-size: 1.8rem;
    font-weight: 800;
    margin-bottom: 0.3rem;
}

.section-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 2rem;
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 3rem 2rem;
    color: var(--text-muted);
}
.empty-state .empty-icon {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}
.empty-state .empty-text {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

/* Notification toast */
.toast-vocstudy {
    position: fixed;
    top: 1.5rem;
    right: 1.5rem;
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-sm);
    padding: 1rem 1.5rem;
    color: var(--text-primary);
    font-weight: 500;
    z-index: 9999;
    transform: translateX(120%);
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    max-width: 360px;
}
.toast-vocstudy.show {
    transform: translateX(0);
}
.toast-vocstudy.success {
    border-left: 4px solid var(--success);
}
.toast-vocstudy.error {
    border-left: 4px solid var(--danger);
}