@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');

:root {
    /* Colors */
    --color-dark: #1C0F13;
    --color-slate: #6E7E85;
    --color-ash: #B7CECE;
    --color-pale: #BBBAC6;
    --color-lightest: #E2E2E2;
    --color-text-primary: #2a2a2a;
    --color-text-secondary: #6E7E85;
    --color-text-muted: #9ca3af;
    --color-bg-primary: #ffffff;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-success: linear-gradient(135deg, #10b981 0%, #059669 100%);
    --gradient-fire: linear-gradient(135deg, #f59e0b 0%, #ef4444 100%);
    --gradient-mesh: 
        radial-gradient(at 27% 37%, rgba(102, 126, 234, 0.05) 0px, transparent 50%),
        radial-gradient(at 97% 21%, rgba(16, 185, 129, 0.05) 0px, transparent 50%),
        radial-gradient(at 52% 99%, rgba(239, 68, 68, 0.05) 0px, transparent 50%);
    
    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    
    /* Typography */
    --font-xs: 0.75rem;
    --font-sm: 0.875rem;
    --font-base: 1rem;
    --font-lg: 1.125rem;
    --font-xl: 1.25rem;
    --font-2xl: 1.5rem;
    --font-3xl: 1.875rem;
    --font-4xl: 2.25rem;
    --font-5xl: 3rem;
    --font-6xl: 3.75rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --color-dark: #f9fafb;
    --color-slate: #d1d5db;
    --color-text-primary: #f9fafb;
    --color-text-secondary: #d1d5db;
    --color-text-muted: #9ca3af;
    --color-bg-primary: #0a0a0a;
    --color-lightest: #1f2937;
    --color-pale: #374151;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* Layout */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-16) var(--space-8);
}

/* Dark Mode Toggle */
.dark-mode-toggle {
    position: fixed;
    top: var(--space-6);
    right: var(--space-6);
    z-index: 1000;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    padding: var(--space-3) var(--space-5);
    cursor: pointer;
    transition: all var(--transition-base);
    font-size: var(--font-sm);
    color: var(--color-text-primary);
    font-weight: 500;
}

.dark-mode-toggle:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Header */
.app-header {
    margin-bottom: var(--space-16);
    animation: fadeInDown 0.6s ease;
}

.app-title {
    font-size: var(--font-5xl);
    font-weight: 800;
    margin-bottom: var(--space-4);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.app-subtitle {
    font-size: var(--font-xl);
    color: var(--color-text-muted);
    font-weight: 300;
    max-width: 600px;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--space-16) var(--space-8);
    animation: fadeInUp 0.8s ease;
}

.empty-state-icon {
    width: 200px;
    height: 200px;
    margin: 0 auto var(--space-8);
    background: var(--gradient-mesh);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.empty-state-icon::before {
    content: '';
    position: absolute;
    inset: -4px;
    background: var(--gradient-primary);
    border-radius: 50%;
    opacity: 0.2;
    filter: blur(20px);
    animation: pulse 3s ease-in-out infinite;
}

.empty-state-svg {
    width: 100px;
    height: 100px;
    stroke: var(--color-slate);
    stroke-width: 2;
    fill: none;
    animation: draw 2s ease-in-out infinite;
}

.empty-state-title {
    font-size: var(--font-4xl);
    font-weight: 700;
    margin-bottom: var(--space-4);
}

.empty-state-text {
    font-size: var(--font-lg);
    color: var(--color-text-muted);
    margin-bottom: var(--space-8);
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.empty-state-checklist {
    display: inline-block;
    text-align: left;
    background: rgba(102, 126, 234, 0.05);
    border: 1px solid rgba(102, 126, 234, 0.1);
    border-radius: 12px;
    padding: var(--space-6);
    margin-bottom: var(--space-8);
}

.checklist-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3);
    font-size: var(--font-base);
    color: var(--color-text-secondary);
}

.checklist-checkbox {
    width: 20px;
    height: 20px;
    border: 2px solid var(--color-slate);
    border-radius: 4px;
    flex-shrink: 0;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-6);
    margin-bottom: var(--space-16);
}

/* Stat Card */
.stat-card {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 16px;
    padding: var(--space-8);
    position: relative;
    overflow: hidden;
    transition: all var(--transition-slow);
    animation: fadeInUp 0.6s ease;
    animation-fill-mode: both;
}

[data-theme="dark"] .stat-card {
    background: rgba(31, 41, 55, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.stat-card:nth-child(2) { animation-delay: 0.1s; }
.stat-card:nth-child(3) { animation-delay: 0.2s; }

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
}

.stat-card.streak::before {
    background: var(--gradient-fire);
}

.stat-card.success::before {
    background: var(--gradient-success);
}

.stat-label {
    font-size: var(--font-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
    margin-bottom: var(--space-4);
}

.stat-value {
    font-size: var(--font-5xl);
    font-weight: 800;
    color: var(--color-text-primary);
    font-feature-settings: 'tnum';
    margin-bottom: var(--space-2);
}

.stat-subtitle {
    font-size: var(--font-sm);
    color: var(--color-text-muted);
}

/* Circular Progress */
.circular-progress {
    position: relative;
    width: 120px;
    height: 120px;
    margin: 0 auto var(--space-4);
}

.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring-circle {
    transition: stroke-dashoffset 1s ease-in-out;
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: var(--font-3xl);
    font-weight: 800;
    color: var(--color-text-primary);
}

/* Writing Heatmap */
.heatmap-section {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 16px;
    padding: var(--space-8);
    margin-bottom: var(--space-16);
    animation: fadeInUp 0.8s ease 0.3s both;
}

[data-theme="dark"] .heatmap-section {
    background: rgba(31, 41, 55, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.heatmap-title {
    font-size: var(--font-2xl);
    font-weight: 700;
    margin-bottom: var(--space-6);
}

.heatmap-grid {
    display: grid;
    grid-template-columns: repeat(53, 1fr);
    gap: 3px;
    margin-bottom: var(--space-4);
}

.heatmap-cell {
    aspect-ratio: 1;
    background: var(--color-lightest);
    border-radius: 2px;
    transition: all var(--transition-fast);
    cursor: pointer;
}

.heatmap-cell:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-md);
}

.heatmap-cell[data-level="1"] { background: rgba(102, 126, 234, 0.2); }
.heatmap-cell[data-level="2"] { background: rgba(102, 126, 234, 0.4); }
.heatmap-cell[data-level="3"] { background: rgba(102, 126, 234, 0.6); }
.heatmap-cell[data-level="4"] { background: rgba(102, 126, 234, 0.8); }
.heatmap-cell[data-level="5"] { background: rgba(102, 126, 234, 1); }

.heatmap-legend {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: var(--font-xs);
    color: var(--color-text-muted);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-8);
    font-size: var(--font-base);
    font-weight: 600;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: all var(--transition-base);
    font-family: inherit;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width var(--transition-slow), height var(--transition-slow);
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
}

.btn-secondary {
    background: rgba(102, 126, 234, 0.1);
    color: var(--color-text-primary);
    border: 1px solid rgba(102, 126, 234, 0.2);
}

.btn-secondary:hover {
    background: rgba(102, 126, 234, 0.2);
    transform: translateY(-2px);
}

.btn-large {
    padding: var(--space-5) var(--space-12);
    font-size: var(--font-lg);
}

/* Goal Selection */
.goal-section {
    margin-bottom: var(--space-16);
    animation: fadeInUp 0.8s ease 0.4s both;
}

.section-title {
    font-size: var(--font-3xl);
    font-weight: 700;
    margin-bottom: var(--space-8);
}

.goal-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-4);
    margin-bottom: var(--space-8);
}

.goal-card {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border: 2px solid transparent;
    border-radius: 12px;
    padding: var(--space-6);
    cursor: pointer;
    transition: all var(--transition-base);
    text-align: center;
}

[data-theme="dark"] .goal-card {
    background: rgba(31, 41, 55, 0.7);
}

.goal-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.goal-card.active {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.1);
    box-shadow: var(--shadow-glow);
}

.goal-number {
    font-size: var(--font-4xl);
    font-weight: 800;
    color: var(--color-text-primary);
    margin-bottom: var(--space-2);
}

.goal-label {
    font-size: var(--font-sm);
    color: var(--color-text-muted);
    font-weight: 500;
}

/* Session History */
.history-section {
    animation: fadeInUp 0.8s ease 0.5s both;
}

.session-timeline {
    position: relative;
    padding-left: var(--space-8);
}

.session-timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(to bottom, #667eea, transparent);
}

.session-item {
    position: relative;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    padding: var(--space-6);
    margin-bottom: var(--space-4);
    transition: all var(--transition-base);
    cursor: pointer;
}

[data-theme="dark"] .session-item {
    background: rgba(31, 41, 55, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.session-item::before {
    content: '';
    position: absolute;
    left: -42px;
    top: 24px;
    width: 12px;
    height: 12px;
    background: #667eea;
    border-radius: 50%;
    border: 3px solid var(--color-bg-primary);
}

.session-item:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-md);
}

/* Fullscreen Editor */
.fullscreen-editor {
    position: fixed;
    inset: 0;
    z-index: 9999;
    background: var(--color-bg-primary);
    display: none;
}

.fullscreen-editor.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

.editor-topbar {
    background: var(--gradient-primary);
    color: white;
    padding: var(--space-6) var(--space-8);
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-lg);
}

.editor-stats {
    display: flex;
    align-items: baseline;
    gap: var(--space-3);
}

.editor-count {
    font-size: var(--font-5xl);
    font-weight: 800;
}

.editor-goal {
    font-size: var(--font-xl);
    opacity: 0.8;
}

.editor-status {
    font-size: var(--font-sm);
    opacity: 0.9;
}

.editor-content {
    height: calc(100vh - 88px);
    overflow-y: auto;
    padding: var(--space-8);
}

.editor-textarea {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    display: block;
    border: none;
    background: transparent;
    font-size: var(--font-xl);
    line-height: 1.8;
    color: var(--color-text-primary);
    resize: none;
    outline: none;
    font-family: inherit;
    min-height: calc(100vh - 200px);
}

/* Celebration */
#confetti-canvas {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 10000;
}

.celebration-modal {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
}

.celebration-modal.active {
    display: flex;
    animation: fadeIn 0.3s ease;
}

.celebration-content {
    background: var(--color-bg-primary);
    border-radius: 24px;
    padding: var(--space-12);
    max-width: 600px;
    text-align: center;
    animation: scaleIn 0.5s var(--transition-spring);
}

.celebration-title {
    font-size: var(--font-5xl);
    font-weight: 800;
    margin-bottom: var(--space-6);
    background: var(--gradient-success);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.celebration-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-6);
    margin-bottom: var(--space-8);
}

.celebration-stat {
    padding: var(--space-6);
    background: rgba(16, 185, 129, 0.1);
    border-radius: 12px;
}

.celebration-stat-value {
    font-size: var(--font-4xl);
    font-weight: 800;
    color: var(--color-success);
}

/* Achievements */
.achievement-toast {
    position: fixed;
    top: var(--space-6);
    right: var(--space-6);
    background: var(--gradient-primary);
    color: white;
    padding: var(--space-4) var(--space-6);
    border-radius: 12px;
    box-shadow: var(--shadow-xl);
    display: none;
    animation: slideInRight 0.5s ease, slideOutRight 0.5s ease 3s;
    z-index: 10000;
}

.achievement-toast.show {
    display: block;
}

/* Keyboard Shortcuts Modal */
.shortcuts-modal {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
}

.shortcuts-modal.active {
    display: flex;
    animation: fadeIn 0.3s ease;
}

.shortcuts-content {
    background: var(--color-bg-primary);
    border-radius: 24px;
    padding: var(--space-8);
    max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
}

.shortcuts-grid {
    display: grid;
    gap: var(--space-4);
}

.shortcut-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-4);
    background: rgba(102, 126, 234, 0.05);
    border-radius: 8px;
}

.shortcut-keys {
    display: flex;
    gap: var(--space-2);
}

.key {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-lightest);
    border-radius: 4px;
    padding: var(--space-1) var(--space-3);
    font-size: var(--font-sm);
    font-weight: 600;
    box-shadow: 0 2px 0 var(--color-lightest);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

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

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes slideInRight {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes slideOutRight {
    to {
        transform: translateX(400px);
        opacity: 0;
    }
}

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

@keyframes draw {
    0%, 100% { stroke-dashoffset: 0; }
    50% { stroke-dashoffset: 1000; }
}

/* Utilities */
.hidden { display: none !important; }
.flex { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: var(--space-8) var(--space-4);
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .goal-grid {
        grid-template-columns: 1fr 1fr;
    }
    
    .app-title {
        font-size: var(--font-4xl);
    }
    
    .empty-state-icon {
        width: 150px;
        height: 150px;
    }
    
    .heatmap-grid {
        display: none;
    }
}