/* ===== DESIGN TOKENS ===== */
:root {
    /* Colors - Light Theme */
    --color-background: #ffffff;
    --color-surface: #f8f9fa;
    --color-surface-elevated: rgba(255, 255, 255, 0.8);
    --color-text-primary: #1d1d1f;
    --color-text-secondary: #86868b;
    --color-text-tertiary: #aeaeb2;
    --color-accent: #007aff;
    --color-accent-light: #409cff;
    --color-border: #e5e5e7;
    --color-shadow: rgba(0, 0, 0, 0.05);

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-surface: linear-gradient(145deg, #ffffff 0%, #f8f9fa 100%);

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-weight-light: 300;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing Scale */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    /* Shadows */
    --shadow-sm: 0 2px 8px var(--color-shadow);
    --shadow-md: 0 8px 30px var(--color-shadow);
    --shadow-lg: 0 16px 48px var(--color-shadow);

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.4s ease;

    /* Blur Effects */
    --backdrop-blur: blur(20px);
}

/* ===== DARK THEME ===== */
[data-theme="dark"] {
    --color-background: #0f1114;
    --color-surface: #1d1f23;
    --color-surface-elevated: rgba(29, 31, 35, 0.8);
    --color-text-primary: #f5f5f7;
    --color-text-secondary: #a1a1a6;
    --color-text-tertiary: #6e6e73;
    --color-accent: #0a84ff;
    --color-accent-light: #409cff;
    --color-border: #2c2c2e;
    --color-shadow: rgba(0, 0, 0, 0.2);

    --gradient-surface: linear-gradient(145deg, #1d1f23 0%, #0f1114 100%);
}

/* ===== BASE STYLES ===== */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-weight: var(--font-weight-regular);
    background: var(--color-background);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

button {
    font-family: inherit;
    border: none;
    background: none;
    cursor: pointer;
}

/* ===== ONBOARDING ===== */
.onboarding {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--gradient-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.8s ease;
}

.onboarding__content {
    text-align: center;
    padding: var(--space-2xl);
    max-width: 400px;
}

.onboarding__icon {
    font-size: 4rem;
    margin-bottom: var(--space-lg);
    animation: bounce 2s infinite;
}

.onboarding__title {
    font-size: 2.5rem;
    font-weight: var(--font-weight-bold);
    color: white;
    margin-bottom: var(--space-md);
    letter-spacing: -0.02em;
}

.onboarding__description {
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--space-2xl);
    line-height: 1.5;
}

.onboarding__button {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: var(--space-md) var(--space-2xl);
    border-radius: var(--radius-xl);
    font-size: 1.1rem;
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.onboarding__button:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

/* ===== MAIN APP ===== */
.app {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--space-lg);
    min-height: 100vh;
    animation: slideUp 0.6s ease;
}

/* ===== HEADER ===== */
.app__header {
    margin-bottom: var(--space-2xl);
}

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

.app__brand {
    display: flex;
    align-items: baseline;
    gap: var(--space-sm);
}

.app__title {
    font-size: 2rem;
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.02em;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.app__subtitle {
    font-size: 0.875rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.app__theme-btn {
    background: var(--color-surface-elevated);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-sm);
    cursor: pointer;
    transition: all var(--transition-normal);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.app__theme-btn:hover {
    transform: scale(1.05);
    border-color: var(--color-accent);
}

/* ===== SEARCH ===== */
.app__search-container {
    position: relative;
}

.app__search {
    font-family: var(--font-family);
    width: 100%;
    padding: var(--space-md) var(--space-md) var(--space-md) 3rem;
    background: var(--color-surface-elevated);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    color: var(--color-text-primary);
    transition: all var(--transition-normal);
}

.app__search:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.1);
}

.search__icon {
    position: absolute;
    left: var(--space-md);
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-tertiary);
}

/* ===== INPUT SECTION ===== */
.app__input-section {
    margin-bottom: var(--space-2xl);
}

.input__container {
    background: var(--color-surface-elevated);
    backdrop-filter: var(--backdrop-blur);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.input__container:focus-within {
    box-shadow: var(--shadow-md);
    border-color: var(--color-accent);
}

.app__textarea {
    font-family: var(--font-family);
    width: 100%;
    border: none;
    background: transparent;
    resize: none;
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text-primary);
    outline: none;
    font-family: var(--font-family);
}

.app__textarea::placeholder {
    color: var(--color-text-tertiary);
}

.input__footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: var(--space-md);
}

.character-count {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    font-weight: var(--font-weight-medium);
}

.app__button {
    background: var(--color-accent);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    padding: var(--space-sm) var(--space-lg);
    font-size: 0.875rem;
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.app__button:hover {
    background: var(--color-accent-light);
    transform: translateY(-1px);
}

.app__button:active {
    transform: translateY(0);
}

/* ===== NOTES SECTION ===== */
.notes__section {
    animation: fadeIn 0.6s ease;
}

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

.section__title {
    font-size: 1.25rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-primary);
}

.notes-count {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    font-weight: var(--font-weight-medium);
}

/* ===== EMPTY STATE ===== */
.empty-state {
    text-align: center;
    padding: var(--space-2xl);
    color: var(--color-text-secondary);
    display: none;
}

.empty-state__icon {
    font-size: 3rem;
    margin-bottom: var(--space-lg);
    opacity: 0.5;
}

.empty-state__title {
    font-size: 1.25rem;
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-sm);
}

.empty-state__description {
    font-size: 1rem;
    opacity: 0.7;
}

.empty-state--visible {
    display: block;
}

/* ===== NOTES GRID ===== */
.notes-grid {
    list-style: none;
    display: grid;
    gap: var(--space-md);
}

.note-card {
    background: var(--color-surface-elevated);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    transition: all var(--transition-normal);
    animation: slideIn 0.4s ease;
    cursor: pointer;
}

.note-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-accent);
}

.note-card__content {
    margin-bottom: var(--space-md);
}

.note-card__text {
    color: var(--color-text-primary);
    line-height: 1.5;
    word-wrap: break-word;
}

.note-card__footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--space-md);
    border-top: 1px solid var(--color-border);
}

.note-card__timestamp {
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
    font-weight: var(--font-weight-medium);
}

.note-card__actions {
    display: flex;
    gap: var(--space-sm);
}

.note-card__action {
    background: none;
    border: none;
    color: var(--color-text-secondary);
    cursor: pointer;
    padding: var(--space-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    font-size: 0.875rem;
}

.note-card__action:hover {
    color: var(--color-accent);
    background: rgba(0, 122, 255, 0.1);
}

/* ===== TOAST ===== */
.toast {
    position: fixed;
    bottom: var(--space-lg);
    right: var(--space-lg);
    background: var(--color-surface-elevated);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-md) var(--space-lg);
    color: var(--color-text-primary);
    font-weight: var(--font-weight-medium);
    box-shadow: var(--shadow-lg);
    transform: translateY(100px);
    opacity: 0;
    transition: all var(--transition-normal);
    z-index: 1000;
}

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

/* ===== ANIMATIONS ===== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes bounce {

    0%,
    20%,
    50%,
    80%,
    100% {
        transform: translateY(0);
    }

    40% {
        transform: translateY(-10px);
    }

    60% {
        transform: translateY(-5px);
    }
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    .app {
        padding: var(--space-md);
    }

    .app__title {
        font-size: 1.75rem;
    }

    .onboarding__content {
        padding: var(--space-xl);
    }

    .onboarding__title {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .app__header-top {
        flex-direction: column;
        gap: var(--space-md);
        align-items: flex-start;
    }

    .input__footer {
        flex-direction: column;
        gap: var(--space-md);
        align-items: stretch;
    }

    .app__button {
        justify-content: center;
    }
}

/* ===== PWA ENHANCEMENTS ===== */
@media (display-mode: standalone) {
    .app {
        padding-top: env(safe-area-inset-top);
        padding-bottom: env(safe-area-inset-bottom);
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --color-border: #000000;
        --color-shadow: rgba(0, 0, 0, 0.3);
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}