:root {
    /* Dark Theme Default */
    --bg-base: #0f172a;
    --bg-surface: #1e293b;
    --bg-surface-hover: #334155;
    
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    
    --border-color: rgba(255, 255, 255, 0.1);
    
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: rgba(99, 102, 241, 0.1);
    
    --streak-color: #f97316;
    --streak-light: rgba(249, 115, 22, 0.1);
    
    --success-color: #10b981;
    --danger-color: #ef4444;
    
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.08);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
    
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-full: 9999px;
    
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
    --bg-base: #f8fafc;
    --bg-surface: #ffffff;
    --bg-surface-hover: #f1f5f9;
    
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    
    --border-color: rgba(0, 0, 0, 0.1);
    
    --glass-bg: rgba(255, 255, 255, 0.8);
    --glass-border: rgba(255, 255, 255, 0.5);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background-color: var(--bg-base);
    color: var(--text-primary);
    min-height: 100vh;
    transition: background-color var(--transition), color var(--transition);
}

/* Typography */
h1, h2, h3 { font-weight: 600; }
.text-muted { color: var(--text-secondary); }

/* Layout */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--bg-surface);
    border-right: 1px solid var(--border-color);
    padding: 24px;
    display: flex;
    flex-direction: column;
    position: sticky;
    top: 0;
    height: 100vh;
    z-index: 10;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 40px;
    color: var(--primary-color);
}

.brand h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex-grow: 1;
}

.nav-links li, .settings-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.nav-links li:hover, .settings-btn:hover {
    background-color: var(--bg-surface-hover);
    color: var(--text-primary);
}

.nav-links li.active {
    background-color: var(--primary-light);
    color: var(--primary-color);
}

.settings-btn {
    margin-top: auto;
}

/* Main Content */
.main-content {
    flex-grow: 1;
    padding: 40px;
    max-width: 1200px;
    margin: 0 auto;
}

.view {
    display: none;
    animation: fadeIn 0.3s ease-out;
}

.view.active-view {
    display: block;
}

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

.view-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-bottom: 32px;
}

.greeting {
    font-size: 2rem;
    margin-bottom: 4px;
}

.date-display {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-bottom: 40px;
}

.stat-card {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px;
    display: flex;
    align-items: center;
    gap: 20px;
    position: relative;
    overflow: hidden;
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--glass-shadow);
    border-color: var(--primary-color);
}

.stat-icon-wrapper {
    width: 64px;
    height: 64px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    z-index: 2;
}

.is-streak { background-color: var(--streak-light); color: var(--streak-color); }
.is-words { background-color: var(--primary-light); color: var(--primary-color); }
.is-total { background-color: rgba(16, 185, 129, 0.1); color: var(--success-color); }

.stat-info { z-index: 2; }
.stat-info h3 {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-weight: 500;
}
.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    display: flex;
    align-items: baseline;
    gap: 8px;
}
.stat-value small {
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.stat-bg-icon {
    position: absolute;
    right: -20px;
    bottom: -20px;
    font-size: 120px;
    color: var(--border-color);
    opacity: 0.5;
    z-index: 1;
    transform: rotate(-15deg);
}

/* Glass Panel */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    padding: 32px;
}

/* Input Section */
.input-header {
    margin-bottom: 24px;
}

.input-header h3 {
    font-size: 1.25rem;
    margin-bottom: 8px;
}

.input-header p {
    color: var(--text-secondary);
}

.input-group {
    display: flex;
    gap: 16px;
    margin-bottom: 12px;
}

input[type="number"] {
    flex-grow: 1;
    background-color: var(--bg-base);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 16px 20px;
    border-radius: var(--radius-md);
    font-size: 1.1rem;
    transition: var(--transition);
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-outline:hover {
    background-color: var(--bg-surface-hover);
    border-color: var(--text-secondary);
}

.btn-danger {
    background-color: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.btn-danger:hover {
    background-color: var(--danger-color);
    color: white;
}

.input-hint {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
}

/* Progress Bar */
.progress-container {
    margin-top: 16px;
}

.progress-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
    font-weight: 500;
}

.progress-percent {
    color: var(--primary-color);
}

.progress-bar-bg {
    width: 100%;
    height: 12px;
    background-color: var(--bg-base);
    border-radius: var(--radius-full);
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), #818cf8);
    width: 0%;
    border-radius: var(--radius-full);
    transition: width 1s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

/* Add a shimmer effect to progress bar */
.progress-bar-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

/* History List */
.history-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-height: 600px;
    overflow-y: auto;
    padding-right: 8px;
}

/* Custom Scrollbar */
.history-list::-webkit-scrollbar {
    width: 6px;
}
.history-list::-webkit-scrollbar-track {
    background: var(--bg-base);
    border-radius: 3px;
}
.history-list::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
    background-color: var(--bg-base);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.history-item:hover {
    border-color: var(--text-secondary);
    background-color: var(--bg-surface-hover);
}

.history-date {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 500;
}

.history-date svg {
    color: var(--text-secondary);
}

.history-words {
    font-weight: 600;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 6px;
}
.history-item.goal-met .history-words {
    color: var(--success-color);
}

.goal-met-icon {
    color: var(--success-color);
    width: 16px;
    height: 16px;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}
.empty-state svg {
    width: 48px;
    height: 48px;
    margin-bottom: 16px;
    opacity: 0.5;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    opacity: 0;
    pointer-events: none;
    transition: var(--transition);
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.modal {
    width: 100%;
    max-width: 480px;
    transform: scale(0.95);
    transition: var(--transition);
}

.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.close-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 4px;
    border-radius: var(--radius-md);
}

.close-btn:hover {
    background-color: var(--bg-surface-hover);
    color: var(--text-primary);
}

.setting-group {
    margin-bottom: 24px;
}

.setting-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

.setting-hint {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 8px;
}

.theme-toggle {
    display: flex;
    gap: 8px;
    background-color: var(--bg-base);
    padding: 4px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.theme-btn {
    flex: 1;
    padding: 10px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: 8px;
    font-weight: 500;
    transition: var(--transition);
}

.theme-btn.active {
    background-color: var(--bg-surface);
    color: var(--text-primary);
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.danger-zone {
    margin-top: 40px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

/* Toast */
.toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background-color: var(--bg-surface);
    color: var(--text-primary);
    padding: 16px 24px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    box-shadow: var(--glass-shadow);
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 1000;
    transform: translateY(150%);
    opacity: 0;
    transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.3s;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast i {
    color: var(--primary-color);
}

.toast.success i { color: var(--success-color); }
.toast.error i { color: var(--danger-color); }

/* Responsive */
@media (max-width: 768px) {
    .app-container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        flex-direction: row;
        align-items: center;
        padding: 16px 24px;
        position: sticky;
    }
    
    .brand { margin-bottom: 0; }
    
    .nav-links {
        flex-direction: row;
        margin-left: auto;
        margin-right: 16px;
    }
    
    .nav-links li span, .settings-btn span {
        display: none;
    }
    
    .settings-btn { margin-top: 0; }
    
    .main-content {
        padding: 24px;
    }
    
    .input-group {
        flex-direction: column;
    }
    .btn { width: 100%; }
}