/* CSS Variables */
:root {
    --color-primary: #4CAF50;
    --color-primary-dark: #388E3C;
    --color-background: #FFFFFF;
    --color-surface: #F5F5F5;
    --color-surface-elevated: #FFFFFF;
    --color-text-primary: #212121;
    --color-text-secondary: #757575;
    --color-border: #E0E0E0;
    --color-danger: #F44336;
    --color-danger-dark: #D32F2F;

    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;

    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;

    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-full: 50%;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
    :root {
        --color-background: #121212;
        --color-surface: #1E1E1E;
        --color-surface-elevated: #2D2D2D;
        --color-text-primary: #FFFFFF;
        --color-text-secondary: #B0B0B0;
        --color-border: #404040;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
        --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    }
}

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.5;
    color: var(--color-text-primary);
    background-color: var(--color-background);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* App Container */
#app {
    max-width: 500px;
    margin: 0 auto;
    min-height: 100vh;
}

/* Screens */
.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* Auth Screen */
.auth-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: var(--spacing-lg);
}

.auth-title {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: var(--spacing-xl);
    color: var(--color-primary);
}

.auth-form {
    width: 100%;
    max-width: 320px;
}

.auth-switch {
    text-align: center;
    margin-top: var(--spacing-md);
    color: var(--color-text-secondary);
}

.auth-switch a {
    color: var(--color-primary);
    text-decoration: none;
    font-weight: 500;
}

.error-message {
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: rgba(244, 67, 54, 0.1);
    border-radius: var(--border-radius-sm);
    color: var(--color-danger);
    text-align: center;
}

/* Form Elements */
.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-base);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    background-color: var(--color-surface);
    color: var(--color-text-primary);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.1);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 500;
    border: none;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    min-height: 44px;
}

.btn-primary {
    width: 100%;
    background-color: var(--color-primary);
    color: white;
}

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

.btn-primary:active {
    transform: scale(0.98);
}

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

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

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

.btn-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    padding: 0;
    background: transparent;
    border: none;
    border-radius: var(--border-radius-full);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: background-color var(--transition-fast);
}

.btn-icon:hover {
    background-color: var(--color-surface);
}

/* Header */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    background-color: var(--color-background);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
}

.header-actions {
    display: flex;
    gap: var(--spacing-xs);
}

/* Day Selector */
.day-selector {
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 76px;
    z-index: 99;
}

.days-container {
    display: flex;
    justify-content: space-between;
    gap: var(--spacing-xs);
}

.day-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm);
    min-width: 44px;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    color: var(--color-text-secondary);
}

.day-item:hover {
    background-color: var(--color-surface);
}

.day-item.active {
    background-color: var(--color-primary);
    color: white;
}

.day-item.today:not(.active) {
    color: var(--color-primary);
    font-weight: 600;
}

.day-name {
    font-size: 12px;
    font-weight: 500;
    text-transform: uppercase;
}

.day-number {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-top: 2px;
}

/* Habits Container */
.habits-container {
    padding: var(--spacing-md);
}

.habits-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

/* Habit Item */
.habit-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--color-surface-elevated);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.habit-item:hover {
    box-shadow: var(--shadow-md);
}

.habit-item:active {
    transform: scale(0.99);
}

.habit-checkbox {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    border-radius: var(--border-radius-full);
    border: 2px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    background-color: transparent;
}

.habit-checkbox.completed {
    border-color: var(--habit-color, var(--color-primary));
    background-color: var(--habit-color, var(--color-primary));
    animation: checkComplete 0.3s ease;
}

.habit-checkbox.completed svg {
    opacity: 1;
    transform: scale(1);
}

.habit-checkbox svg {
    width: 18px;
    height: 18px;
    color: white;
    opacity: 0;
    transform: scale(0.5);
    transition: all var(--transition-normal);
}

@keyframes checkComplete {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.habit-content {
    flex: 1;
    min-width: 0;
}

.habit-name {
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-xs);
}

.habit-intention {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* Empty State */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl);
    text-align: center;
    color: var(--color-text-secondary);
}

.empty-state p {
    margin-bottom: var(--spacing-md);
}

.empty-state .btn {
    width: auto;
}

/* Dropdown Menu */
.dropdown {
    position: absolute;
    top: 60px;
    right: var(--spacing-md);
    background-color: var(--color-surface-elevated);
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    z-index: 200;
}

.dropdown-item {
    display: block;
    width: 100%;
    padding: var(--spacing-md);
    font-size: var(--font-size-base);
    text-align: left;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text-primary);
    transition: background-color var(--transition-fast);
}

.dropdown-item:hover {
    background-color: var(--color-surface);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: flex-end;
    justify-content: center;
    z-index: 300;
    padding: 0;
}

.modal-content {
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    background-color: var(--color-background);
    border-radius: var(--border-radius) var(--border-radius) 0 0;
    padding: var(--spacing-lg);
    animation: slideUp 0.3s ease;
}

.modal-small {
    max-height: auto;
}

.modal-small p {
    margin: var(--spacing-md) 0;
    color: var(--color-text-secondary);
}

@keyframes slideUp {
    from {
        transform: translateY(100%);
    }
    to {
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.modal-header h2 {
    font-size: var(--font-size-lg);
    font-weight: 600;
}

/* Intention Section */
.intention-section {
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--color-surface);
    border-radius: var(--border-radius-sm);
}

.intention-section > label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

.intention-preview {
    font-size: var(--font-size-base);
    color: var(--color-primary);
    font-style: italic;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-sm);
    background-color: var(--color-background);
    border-radius: var(--border-radius-sm);
}

/* Color Picker */
.color-picker {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.color-option {
    width: 36px;
    height: 36px;
    border-radius: var(--border-radius-full);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.color-option:hover {
    transform: scale(1.1);
}

.color-option.selected {
    border-color: var(--color-text-primary);
    box-shadow: 0 0 0 2px var(--color-background);
}

/* Day Picker */
.day-picker {
    display: flex;
    gap: var(--spacing-xs);
}

.day-option {
    flex: 1;
    padding: var(--spacing-sm);
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-align: center;
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    background-color: transparent;
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.day-option:hover {
    border-color: var(--color-primary);
}

.day-option.selected {
    border-color: var(--color-primary);
    background-color: var(--color-primary);
    color: white;
}

.form-hint {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

/* Inactive habit (not scheduled for current day) */
.habit-item.inactive-day {
    opacity: 0.4;
}

.habit-item.inactive-day .habit-checkbox {
    pointer-events: none;
}

/* Form Actions */
.form-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.form-actions .btn {
    flex: 1;
}

.form-actions .btn-danger {
    flex: 0 0 auto;
    width: auto;
    padding: var(--spacing-sm) var(--spacing-md);
}

/* Safe Area for iOS */
@supports (padding-bottom: env(safe-area-inset-bottom)) {
    .modal-content {
        padding-bottom: calc(var(--spacing-lg) + env(safe-area-inset-bottom));
    }
}

/* Animations */
.habit-item {
    animation: fadeInUp 0.3s ease backwards;
}

.habit-item:nth-child(1) { animation-delay: 0.05s; }
.habit-item:nth-child(2) { animation-delay: 0.1s; }
.habit-item:nth-child(3) { animation-delay: 0.15s; }
.habit-item:nth-child(4) { animation-delay: 0.2s; }
.habit-item:nth-child(5) { animation-delay: 0.25s; }
.habit-item:nth-child(6) { animation-delay: 0.3s; }
.habit-item:nth-child(7) { animation-delay: 0.35s; }
.habit-item:nth-child(8) { animation-delay: 0.4s; }

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

/* Loading Spinner */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl);
}

.spinner {
    width: 32px;
    height: 32px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    bottom: calc(var(--spacing-lg) + env(safe-area-inset-bottom, 0px));
    left: 50%;
    transform: translateX(-50%);
    z-index: 400;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    pointer-events: none;
}

.toast {
    background-color: var(--color-text-primary);
    color: var(--color-background);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-sm);
    box-shadow: var(--shadow-lg);
    animation: toastIn 0.3s ease, toastOut 0.3s ease 2.7s forwards;
    pointer-events: auto;
}

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

.toast.error {
    background-color: var(--color-danger);
    color: white;
}

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

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

/* Pull to Refresh Indicator */
.pull-indicator {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

.pull-indicator.refreshing .spinner {
    width: 20px;
    height: 20px;
    border-width: 2px;
}

/* Button Loading State */
.btn.loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    top: 50%;
    left: 50%;
    margin: -10px 0 0 -10px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

/* Skeleton Loading */
.skeleton {
    background: linear-gradient(
        90deg,
        var(--color-surface) 25%,
        var(--color-border) 50%,
        var(--color-surface) 75%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: var(--border-radius-sm);
}

.skeleton-habit {
    height: 80px;
    margin-bottom: var(--spacing-sm);
}

@keyframes shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Completed habit styling */
.habit-item.completed-today {
    opacity: 0.7;
}

.habit-item.completed-today .habit-name {
    text-decoration: line-through;
    text-decoration-color: var(--color-text-secondary);
}

/* Day item improvements */
.day-item {
    position: relative;
}

.day-item.has-completions::after {
    content: '';
    position: absolute;
    bottom: 4px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 4px;
    background-color: var(--color-primary);
    border-radius: 50%;
}

.day-item.active.has-completions::after {
    background-color: white;
}