:root {
    --primary-color: #5E35B1;
    --primary-light: #7E57C2;
    --primary-dark: #4527A0;
    --secondary-color: #00ACC1;
    --success-color: #4CAF50;
    --warning-color: #FF9800;
    --danger-color: #F44336;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F5F5F5;
    --bg-tertiary: #FAFAFA;
    --text-primary: #212121;
    --text-secondary: #757575;
    --text-tertiary: #9E9E9E;
    --border-color: #E0E0E0;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
    --shadow-md: 0 3px 6px rgba(0,0,0,0.15), 0 2px 4px rgba(0,0,0,0.12);
    --shadow-lg: 0 10px 20px rgba(0,0,0,0.15), 0 3px 6px rgba(0,0,0,0.10);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-theme {
    --primary-color: #7E57C2;
    --primary-light: #9575CD;
    --primary-dark: #5E35B1;
    --bg-primary: #121212;
    --bg-secondary: #1E1E1E;
    --bg-tertiary: #2C2C2C;
    --text-primary: #FFFFFF;
    --text-secondary: #B0B0B0;
    --text-tertiary: #808080;
    --border-color: #404040;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: var(--transition);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    padding: 20px 30px;
    margin-bottom: 30px;
    box-shadow: var(--shadow-sm);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app-title {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 28px;
    font-weight: 700;
    color: var(--primary-color);
}

.logo {
    color: var(--primary-color);
}

.header-controls {
    display: flex;
    gap: 15px;
    align-items: center;
}

.language-select {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

.language-select:hover {
    border-color: var(--primary-color);
}

.theme-toggle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: none;
    background: var(--bg-secondary);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.theme-toggle:hover {
    background: var(--primary-light);
    color: white;
}

.sun-icon,
.moon-icon {
    position: absolute;
    transition: opacity 0.3s;
}

.dark-theme .sun-icon {
    opacity: 0;
}

.dark-theme .moon-icon {
    opacity: 1;
}

body:not(.dark-theme) .sun-icon {
    opacity: 1;
}

body:not(.dark-theme) .moon-icon {
    opacity: 0;
}

/* Stats */
.stats-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background: var(--bg-primary);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    text-align: center;
    transition: var(--transition);
}

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

.stat-value {
    font-size: 36px;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Main Content */
.main-content {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 30px;
}

@media (max-width: 968px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}

/* Habits Section */
.habits-section,
.calendar-section {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    padding: 25px;
    box-shadow: var(--shadow-sm);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.section-header h2 {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--border-color);
}

/* Habits List */
.habits-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.no-habits {
    text-align: center;
    padding: 40px;
    color: var(--text-secondary);
    font-size: 16px;
}

.habit-card {
    background: var(--bg-secondary);
    border-radius: 10px;
    padding: 20px;
    transition: var(--transition);
    border: 2px solid transparent;
}

.habit-card.completed {
    border-color: var(--success-color);
    background: linear-gradient(135deg, rgba(76, 175, 80, 0.05) 0%, rgba(76, 175, 80, 0.1) 100%);
}

.habit-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
}

.habit-info {
    flex: 1;
}

.habit-name {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.habit-category {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 12px;
    color: white;
    font-weight: 500;
}

.habit-actions {
    display: flex;
    gap: 10px;
}

.habit-check {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 2px solid var(--border-color);
    background: var(--bg-primary);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    color: white;
}

.habit-check:hover {
    border-color: var(--primary-color);
    transform: scale(1.1);
}

.habit-check.checked {
    background: var(--success-color);
    border-color: var(--success-color);
}

.habit-delete {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: none;
    background: transparent;
    color: var(--text-tertiary);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.habit-stats {
    display: flex;
    gap: 20px;
    margin-bottom: 15px;
    flex-wrap: wrap;
}

.habit-stat {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    color: var(--text-secondary);
}

.stat-icon {
    font-size: 16px;
}

.habit-progress {
    display: flex;
    align-items: center;
    gap: 15px;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: var(--border-color);
    border-radius: 10px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    border-radius: 10px;
    transition: width 0.5s ease;
}

.progress-text {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary-color);
    min-width: 45px;
    text-align: right;
}

/* Calendar */
.calendar-nav {
    display: flex;
    align-items: center;
    gap: 15px;
}

.calendar-nav-btn {
    width: 32px;
    height: 32px;
    border-radius: 8px;
    border: none;
    background: var(--bg-secondary);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.calendar-nav-btn:hover {
    background: var(--primary-light);
    color: white;
}

.current-month {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    min-width: 120px;
    text-align: center;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
    margin-top: 20px;
}

.calendar-weekday {
    text-align: center;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-secondary);
    padding: 8px 0;
    text-transform: uppercase;
}

.calendar-day {
    aspect-ratio: 1;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    background: var(--bg-secondary);
}

.calendar-day:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-sm);
}

.calendar-day.other-month {
    opacity: 0.3;
}

.calendar-day.today {
    border: 2px solid var(--primary-color);
    font-weight: 600;
}

.calendar-day.day-completed {
    background: var(--success-color);
    color: white;
}

.calendar-day.day-partial {
    background: var(--warning-color);
    color: white;
}

.calendar-day.day-none {
    background: var(--bg-secondary);
}

.day-number {
    font-size: 14px;
}

.day-indicator {
    font-size: 10px;
    position: absolute;
    bottom: 2px;
    opacity: 0.8;
}

.calendar-legend {
    display: flex;
    gap: 20px;
    margin-top: 20px;
    justify-content: center;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
    color: var(--text-secondary);
}

.legend-color {
    width: 16px;
    height: 16px;
    border-radius: 4px;
}

.legend-completed {
    background: var(--success-color);
}

.legend-partial {
    background: var(--warning-color);
}

.legend-none {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 1000;
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    padding: 30px;
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    transform: scale(0.9);
    transition: var(--transition);
}

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

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
}

.modal-header h3 {
    font-size: 22px;
    font-weight: 600;
    color: var(--text-primary);
}

.modal-close {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: var(--bg-secondary);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

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

/* Form */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 15px;
    transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(94, 53, 177, 0.1);
}

.modal-actions {
    display: flex;
    gap: 15px;
    justify-content: flex-end;
    margin-top: 25px;
}

/* Notification */
.notification {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: var(--primary-color);
    color: white;
    padding: 15px 25px;
    border-radius: 8px;
    box-shadow: var(--shadow-lg);
    transform: translateY(100px);
    opacity: 0;
    transition: var(--transition);
    z-index: 2000;
    font-size: 14px;
    font-weight: 500;
}

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

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .header {
        flex-direction: column;
        gap: 15px;
        padding: 20px;
    }
    
    .app-title {
        font-size: 24px;
    }
    
    .stats-container {
        grid-template-columns: repeat(2, 1fr);
        gap: 15px;
    }
    
    .stat-value {
        font-size: 28px;
    }
    
    .main-content {
        gap: 20px;
    }
    
    .habits-section,
    .calendar-section {
        padding: 20px;
    }
    
    .modal-content {
        padding: 20px;
    }
    
    .calendar-grid {
        gap: 2px;
    }
    
    .calendar-day {
        font-size: 12px;
    }
    
    .day-indicator {
        font-size: 8px;
    }
}

@media (max-width: 480px) {
    .stats-container {
        grid-template-columns: 1fr;
    }
    
    .habit-stats {
        gap: 10px;
    }
    
    .calendar-legend {
        flex-wrap: wrap;
        gap: 10px;
    }
}