/* ===== CSS Variables ===== */
:root {
    /* Light Mode Colors */
    --bg-primary: #FDFCF9;
    --bg-secondary: #F5F1E8;
    --surface: #FFFFFF;
    --text-primary: #2C2C2C;
    --text-secondary: #6B6B6B;
    --text-muted: #9B9B9B;
    
    /* Accent Colors - Soft neutrals */
    --sage: #A8B5A0;
    --clay: #C4A484;
    
    /* Default accent (customizable) */
    --accent: var(--sage);
    
    /* Borders & Shadows */
    --border: rgba(0, 0, 0, 0.06);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2.5rem;
    --spacing-xl: 4rem;
    
    /* Border Radius */
    --radius: 16px;
    --radius-sm: 12px;
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro', sans-serif;
}

/* Dark Mode */
[data-theme="dark"] {
    --bg-primary: #1A1A1A;
    --bg-secondary: #242424;
    --surface: #2A2A2A;
    --text-primary: #E8E8E8;
    --text-secondary: #B0B0B0;
    --text-muted: #808080;
    --border: rgba(255, 255, 255, 0.08);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
}

/* ===== Reset & Base Styles ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-primary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.app-container {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
    position: relative;
}

/* ===== Screen Management ===== */
.screen {
    display: none;
    animation: fadeIn 0.4s ease-out;
}

.screen-active {
    display: block;
}

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

/* ===== Header ===== */
.app-header {
    text-align: center;
    padding: var(--spacing-xl) 0 var(--spacing-lg);
}

.app-title {
    font-size: 3rem;
    font-weight: 300;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.app-tagline {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 400;
    max-width: 400px;
    margin: 0 auto;
    font-style: italic;
}

/* ===== Login Screen ===== */
.login-content {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    padding: var(--spacing-xl) 0;
}

.login-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: var(--spacing-xl);
    width: 100%;
    max-width: 400px;
    box-shadow: var(--shadow-md);
}

.login-title {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    text-align: center;
}

.login-subtitle {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.email-input {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: var(--spacing-md);
    font-size: 1rem;
    font-family: var(--font-primary);
    color: var(--text-primary);
    background: var(--surface);
    transition: all 0.3s ease;
}

.email-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(168, 181, 160, 0.1);
}

.login-status {
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    text-align: center;
    min-height: 20px;
}

.login-status.success {
    color: var(--sage);
    background: rgba(168, 181, 160, 0.1);
}

.login-status.error {
    color: #E53E3E;
    background: rgba(229, 62, 62, 0.1);
}

/* ===== Home Content ===== */
.home-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    padding-bottom: var(--spacing-xl);
}

.button-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    align-items: center;
}

.date-display {
    text-align: center;
    font-size: 0.9rem;
    color: var(--text-muted);
    font-weight: 400;
    letter-spacing: 0.02em;
}

.entry-locked-message {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 400;
    letter-spacing: 0.02em;
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-sm);
}

/* ===== Buttons ===== */
.btn-primary {
    background: var(--accent);
    color: white;
    border: none;
    border-radius: var(--radius);
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: 1.1rem;
    font-weight: 500;
    font-family: var(--font-primary);
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
    max-width: 400px;
    margin: 0 auto;
    display: block;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    opacity: 0.9;
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.btn-back {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
    opacity: 0.7;
}

.btn-back:hover {
    opacity: 1;
    background: var(--bg-secondary);
}

/* ===== Writing Screen ===== */
.writing-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) 0 var(--spacing-lg);
}

.writing-title {
    font-size: 1.25rem;
    font-weight: 400;
    color: var(--text-primary);
    flex: 1;
    text-align: center;
}

.appreciation-input:disabled {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    cursor: not-allowed;
}

.writing-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    padding-bottom: var(--spacing-xl);
}

.input-container {
    position: relative;
}

.appreciation-input {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--spacing-md);
    font-size: 1.1rem;
    font-family: var(--font-primary);
    color: var(--text-primary);
    background: var(--surface);
    resize: none;
    min-height: 140px;
    transition: all 0.3s ease;
    line-height: 1.7;
}

.appreciation-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(168, 181, 160, 0.1);
}

.appreciation-input::placeholder {
    color: var(--text-muted);
}

.char-counter {
    position: absolute;
    bottom: var(--spacing-sm);
    right: var(--spacing-sm);
    font-size: 0.85rem;
    color: var(--text-muted);
    background: var(--surface);
    padding: 2px 8px;
    border-radius: 6px;
}

.btn-save {
    margin-top: var(--spacing-sm);
}

/* ===== Recent Entries ===== */
.recent-entries {
    margin-top: var(--spacing-lg);
}

.recent-entries-title {
    font-size: 0.9rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
    font-weight: 500;
}

.entry-preview {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    transition: all 0.2s ease;
    cursor: pointer;
}

.entry-preview:hover {
    border-color: var(--accent);
    transform: translateX(4px);
}

.entry-preview-date {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-xs);
    font-weight: 400;
}

.entry-preview-content {
    font-size: 0.95rem;
    color: var(--text-primary);
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.empty-recent {
    text-align: center;
    padding: var(--spacing-lg);
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* ===== Action Buttons ===== */
.action-buttons {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    margin-top: var(--spacing-lg);
    flex-wrap: wrap;
}

/* ===== Notification Settings ===== */
.notification-settings {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
}

.notification-toggle-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
}

.notification-info {
    flex: 1;
}

.notification-title {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.notification-description {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

.notification-toggle-btn {
    position: relative;
    width: 50px;
    height: 28px;
    border-radius: 14px;
    border: 1px solid var(--border);
    background: var(--bg-secondary);
    cursor: pointer;
    transition: all 0.3s ease;
    padding: 0;
    flex-shrink: 0;
}

.notification-toggle-btn:hover {
    border-color: var(--accent);
}

.notification-toggle-btn.enabled {
    background: var(--accent);
    border-color: var(--accent);
}

.toggle-slider {
    position: absolute;
    top: 2px;
    left: 2px;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: white;
    transition: transform 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.notification-toggle-btn.enabled .toggle-slider {
    transform: translateX(22px);
}

.btn-secondary {
    background: var(--surface);
    border: 1px solid var(--border);
    color: var(--text-primary);
    border-radius: var(--radius-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9rem;
    font-weight: 400;
    font-family: var(--font-primary);
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    border-color: var(--accent);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-text-small {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 0.85rem;
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
}

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

/* ===== Modal ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.2s ease-out;
}

.modal.show {
    display: flex;
}

.modal-content {
    background: var(--surface);
    border-radius: var(--radius);
    padding: var(--spacing-lg);
    max-width: 400px;
    width: 90%;
    box-shadow: var(--shadow-md);
    animation: slideUp 0.3s ease-out;
}

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

.modal-title {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.modal-text {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

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

.modal-buttons .btn-primary,
.modal-buttons .btn-secondary {
    width: 100%;
    margin: 0;
}

/* ===== Calendar Screen ===== */
.calendar-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) 0 var(--spacing-lg);
}

.calendar-title {
    font-size: 1.25rem;
    font-weight: 400;
    color: var(--text-primary);
    flex: 1;
}

.calendar-content {
    padding-bottom: var(--spacing-xl);
}

.calendar-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-md);
}

.calendar-nav h3 {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-primary);
}

.btn-nav {
    background: var(--surface);
    border: 1px solid var(--border);
    color: var(--text-primary);
    border-radius: var(--radius-sm);
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.5rem;
    transition: all 0.2s ease;
}

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

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.calendar-day-header {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
    padding: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.calendar-day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.9rem;
    color: var(--text-primary);
    background: var(--surface);
    border: 1px solid var(--border);
}

.calendar-day:hover {
    background: var(--bg-secondary);
    border-color: var(--accent);
}

.calendar-day.other-month {
    color: var(--text-muted);
    opacity: 0.4;
}

.calendar-day.today {
    border-color: var(--accent);
    font-weight: 500;
}

.calendar-day.has-entry {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
    font-weight: 500;
}

.calendar-day.has-entry.other-month {
    opacity: 0.6;
}

/* ===== Dark Mode Toggle ===== */
.dark-mode-toggle {
    position: fixed;
    bottom: var(--spacing-md);
    right: var(--spacing-md);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: var(--surface);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    z-index: 100;
}

.dark-mode-toggle:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

/* ===== Toast Notification ===== */
.toast {
    position: fixed;
    bottom: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--text-primary);
    color: var(--bg-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-md);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 1000;
    max-width: 90%;
    text-align: center;
    font-size: 0.9rem;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* ===== Save Animation ===== */
@keyframes saveSuccess {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(0.95);
    }
    100% {
        transform: scale(1);
    }
}

.btn-save.saving {
    animation: saveSuccess 0.4s ease;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .app-container {
        padding: var(--spacing-sm);
    }

    .app-title {
        font-size: 2.5rem;
    }

    .app-header {
        padding: var(--spacing-lg) 0 var(--spacing-md);
    }

    .home-content {
        gap: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .app-title {
        font-size: 2rem;
    }

    .btn-primary {
        font-size: 1rem;
        padding: var(--spacing-sm) var(--spacing-md);
    }
}

/* ===== Print Styles ===== */
@media print {
    .dark-mode-toggle,
    .btn-primary,
    .btn-back {
        display: none;
    }
}