:root {
    --bg-primary: #ffffff;
    --bg-secondary: #fdfdfd;
    --accent-pink: #ffb7c5;
    --accent-pink-dark: #ea9ab2;
    --accent-purple: #dcd0ff;
    --accent-blue: #b9e0ff;
    --accent-green: #c1f2cc;
    --accent-red: #ffc2c2;
    --text-primary: #2d2d2d;
    --text-secondary: #71717a;
    --glass-border: rgba(0, 0, 0, 0.05);
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    --nav-height: 70px;
    --transition-smooth: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Outfit', sans-serif;
}

body {
    background-color: #ffffff;
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    line-height: 1.6;
}

/* Minimalist Glassmorphism */
.glass {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    box-shadow: var(--glass-shadow);
}

/* Base Layout */
#app {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;
    padding: calc(var(--nav-height) + 3rem) 2rem 3rem;
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

/* Navigation - SaaS Minimalist Style */
.glass-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
    display: flex;
    align-items: center;
}

.nav-content {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 700;
    font-size: 1.6rem;
    background: linear-gradient(135deg, var(--accent-pink-dark), var(--accent-pink));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    cursor: pointer;
    transition: transform 0.2s ease;
}

.logo:hover {
    transform: scale(1.02);
}

.logo:active {
    transform: scale(0.98);
}

.logo-icon {
    width: 28px;
    height: 28px;
    stroke: var(--accent-pink-dark);
}

.sync-badge {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.8rem;
    font-weight: 600;
    color: #6aa84f;
    background: rgba(193, 242, 204, 0.2);
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    margin-right: auto;
    margin-left: 1.5rem;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.sync-badge.syncing {
    color: #5b9bd5;
    background: rgba(185, 224, 255, 0.2);
    opacity: 1;
}

.sync-badge.synced {
    opacity: 1;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
}

.nav-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 0.6rem 1.25rem;
    border-radius: 14px;
    cursor: pointer;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition-smooth);
}

.nav-btn:hover {
    color: var(--text-primary);
    background: rgba(255, 183, 197, 0.1);
}

.nav-btn.active {
    color: var(--accent-pink-dark);
    background: rgba(255, 183, 197, 0.15);
}

/* Dashboard Styles */
.view-header {
    margin-bottom: 3rem;
    text-align: center;
}

.view-header h1 {
    font-size: 2.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.2rem;
}

.decks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2.5rem;
    padding-top: 2rem;
}

.deck-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    cursor: pointer;
    transition: var(--transition-smooth);
    background: #ffffff;
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    overflow: hidden;
}

.deck-card:hover {
    transform: translateY(-8px);
    border-color: var(--accent-pink);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.05);
}

.deck-main-area {
    padding: 2.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    flex: 1;
}

.deck-actions {
    width: 100%;
    border-top: 1px solid var(--glass-border);
    display: flex;
}

.deck-edit-btn {
    flex: 1;
    background: transparent;
    border: none;
    padding: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-smooth);
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
}

.deck-edit-btn:hover {
    background: rgba(0, 0, 0, 0.02);
    color: var(--accent-pink-dark);
}

.create-deck-card {
    justify-content: center;
    border: 2px dashed #d1d5db;
    background: transparent;
    padding: 2.5rem;
}

.create-deck-card:hover {
    border-color: var(--accent-pink-dark);
    background: rgba(255, 183, 197, 0.05);
}

.create-icon {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: var(--accent-pink-dark);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    box-shadow: 0 4px 15px rgba(234, 154, 178, 0.3);
}

.cards-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.card-list-item {
    padding: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    text-align: left;
    flex-wrap: wrap;
    gap: 1rem;
}

.card-item-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex: 1;
    min-width: 200px;
}

.card-item-actions {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.edit-card-btn {
    background: transparent;
    border: none;
    color: #3b82f6;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: var(--transition-smooth);
}
.edit-card-btn:hover {
    background: #eff6ff;
}

.del-card-btn {
    background: transparent;
    border: none;
    color: #ef4444;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: var(--transition-smooth);
}
.del-card-btn:hover {
    background: #fee2e2;
}

.delete-link {
    background: #fffafa;
    border: 1px solid #ffcccc;
    color: #ef4444;
    padding: 0.5rem 1rem;
    border-radius: 12px;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    transition: var(--transition-smooth);
}

.delete-link:hover {
    background: #fee2e2;
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(239, 68, 68, 0.1);
}

.deck-card h3 {
    font-size: 1.4rem;
    margin-bottom: 0.5rem;
}

.deck-card p {
    color: var(--text-secondary);
    font-weight: 500;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.stat-card {
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1rem;
}

.stat-icon {
    width: 56px;
    height: 56px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.5rem;
}

.stat-icon.purple { background: rgba(220, 208, 255, 0.4); color: #8e7cc3; }
.stat-icon.blue { background: rgba(185, 224, 255, 0.4); color: #5b9bd5; }
.stat-icon.green { background: rgba(193, 242, 204, 0.4); color: #6aa84f; }

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 500;
}

/* CTA Buttons */
.cta-button {
    padding: 1rem 2rem;
    border-radius: 18px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    transition: var(--transition-smooth);
}

.cta-button.primary {
    background: var(--accent-pink-dark);
    color: white;
    box-shadow: 0 4px 15px rgba(234, 154, 178, 0.3);
}

.cta-button.primary:hover {
    transform: translateY(-2px);
    background: #d8809a;
    box-shadow: 0 8px 25px rgba(234, 154, 178, 0.4);
}

.cta-button.secondary {
    background: #f1f5f9;
    color: var(--text-primary);
    border: 1px solid #cbd5e1;
}

.cta-button.secondary:hover {
    transform: translateY(-2px);
    background: #e2e8f0;
}

.action-section {
    display: flex;
    justify-content: center;
}

.cta-button.primary.large {
    animation: softPulse 3s infinite ease-in-out;
}

@keyframes softPulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.02); box-shadow: 0 10px 30px rgba(234, 154, 178, 0.4); }
    100% { transform: scale(1); }
}

/* Study View Layout */
.study-container {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    width: 100%;
}

.study-header {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    width: 100%;
    margin-bottom: 2rem;
}

.back-btn {
    background: white;
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: var(--transition-smooth);
    box-shadow: 0 4px 10px rgba(0,0,0,0.03);
    flex-shrink: 0;
}

.back-btn:hover {
    color: var(--accent-pink-dark);
    border-color: var(--accent-pink);
    transform: translateX(-3px);
}

.study-header .progress-bar-container {
    margin-bottom: 0;
    flex-grow: 1;
}
.progress-bar-container {
    width: 100%;
    height: 8px;
    background: #f1f5f9;
    border-radius: 4px;
    margin-bottom: 3rem;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--accent-pink-dark);
    border-radius: 4px;
    transition: width 0.3s ease;
}

.card-display {
    width: 100%;
    height: 480px;
    perspective: 1000px;
    margin-bottom: 2rem;
}

/* Flashcard - Clean Light Style */
.flashcard {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    padding: 3rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    border-radius: 36px;
    background: #ffffff;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.03);
    border: 1px solid var(--glass-border);
}

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

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

.card-type {
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 2px;
    color: var(--accent-pink-dark);
    font-weight: 700;
    margin-bottom: 2rem;
}

#card-question, #card-answer {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
}

.card-hint {
    margin-top: 3rem;
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Ratings */
.rating-controls {
    display: flex;
    gap: 1rem;
    width: 100%;
    margin-top: 3rem;
    justify-content: center;
    flex-wrap: wrap;
}

.rate-btn {
    flex: 1;
    padding: 1rem;
    border-radius: 16px;
    border: 1px solid var(--glass-border);
    background: #f8f9fa;
    color: var(--text-primary);
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition-smooth);
}

.rate-btn.again:hover { background: #fee2e2; color: #ef4444; border-color: #fee2e2; }
.rate-btn.hard:hover { background: #fef3c7; color: #d97706; border-color: #fef3c7; }
.rate-btn.good:hover { background: #dbeafe; color: #2563eb; border-color: #dbeafe; }
.rate-btn.easy:hover { background: #dcfce7; color: #16a34a; border-color: #dcfce7; }

/* Form Elements */
.form-container {
    max-width: 700px;
    margin: 0 auto;
    padding: 3rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.input-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

textarea, input {
    width: 100%;
    padding: 1.2rem;
    background: #fdfdfd;
    border: 1.5px solid #efefef;
    border-radius: 20px;
    color: var(--text-primary);
    font-size: 1.1rem;
    transition: var(--transition-smooth);
}

textarea {
    height: 150px;
    resize: vertical;
}

textarea:focus, input:focus {
    outline: none;
    border-color: var(--accent-pink);
    background: #ffffff;
    box-shadow: 0 0 0 4px rgba(255, 183, 197, 0.1);
}

.form-actions {
    display: flex;
    justify-content: center;
    margin-top: 1rem;
}

/* View Animations */
.view {
    display: none;
    animation: slideUp 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.view.active { display: block; }

/* Modal Styles */
.modal {
    position: fixed;
    inset: 0;
    z-index: 9999;
    background: rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    backdrop-filter: blur(4px);
    transition: opacity 0.3s ease;
}

.modal.hidden {
    opacity: 0;
    pointer-events: none;
}

.hidden {
    display: none !important;
}

.modal-content {
    background: #fff;
    width: 100%;
    max-width: 400px;
    border-radius: 24px;
    padding: 2rem;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    transform: translateY(0);
    transition: transform 0.3s ease;
}

.modal.hidden .modal-content {
    transform: translateY(20px);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.close-modal-btn {
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0.5rem;
    display: flex;
    border-radius: 50%;
    transition: var(--transition-smooth);
}
.close-modal-btn:hover { 
    color: var(--text-primary); 
    background: rgba(0,0,0,0.05);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
}

/* Responsive adjustments (Mobile First already applied via flex) */
@media (max-width: 1024px) {
    .stats-grid { grid-template-columns: 1fr; }
    
    #btn-home { display: none !important; }
    
    .nav-btn { padding: 0.6rem 1rem; }
    .rating-controls { flex-direction: column; }
    .view-header h1 { font-size: 2.1rem; }
    .form-actions { flex-direction: column; width: 100%; gap: 1rem; }
    .form-actions .cta-button { width: 100%; justify-content: center; }
    .modal-footer { flex-direction: column-reverse; }
    .modal-footer .cta-button { width: 100%; justify-content: center; }
}