/**
 * Readable Web - Mobile-First Responsive CSS
 * Clean, distraction-free reading experience
 */

/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
    /* Colors */
    --color-primary: #1a73e8;
    --color-primary-dark: #1557b0;
    --color-primary-light: #e8f0fe;
    --color-background: #ffffff;
    --color-surface: #f8f9fa;
    --color-text-primary: #202124;
    --color-text-secondary: #5f6368;
    --color-text-tertiary: #80868b;
    --color-border: #dadce0;
    --color-error: #d93025;
    --color-error-bg: #fce8e6;
    --color-success: #1e8e3e;
    --color-overlay: rgba(0, 0, 0, 0.5);
    
    /* Typography */
    --font-family-base: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-family-heading: var(--font-family-base);
    --font-family-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;
    
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-md: 1.125rem;  /* 18px */
    --font-size-lg: 1.25rem;    /* 20px */
    --font-size-xl: 1.5rem;     /* 24px */
    --font-size-2xl: 1.875rem;  /* 30px */
    --font-size-3xl: 2.25rem;   /* 36px */
    
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    --line-height-loose: 2;
    
    /* Spacing */
    --space-1: 0.25rem;   /* 4px */
    --space-2: 0.5rem;    /* 8px */
    --space-3: 0.75rem;   /* 12px */
    --space-4: 1rem;       /* 16px */
    --space-5: 1.25rem;   /* 20px */
    --space-6: 1.5rem;    /* 24px */
    --space-8: 2rem;      /* 32px */
    --space-10: 2.5rem;   /* 40px */
    --space-12: 3rem;     /* 48px */
    --space-16: 4rem;     /* 64px */
    
    /* Layout */
    --content-max-width: 680px;
    --header-height: 56px;
    --input-card-max-width: 480px;
    
    /* Borders */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Safe Areas (for notched devices) */
    --safe-area-top: env(safe-area-inset-top, 0px);
    --safe-area-bottom: env(safe-area-inset-bottom, 0px);
    --safe-area-left: env(safe-area-inset-left, 0px);
    --safe-area-right: env(safe-area-inset-right, 0px);
}

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    -webkit-tap-highlight-color: transparent;
}

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

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Better focus styles */
:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Remove default button styles */
button {
    font-family: inherit;
    font-size: inherit;
    cursor: pointer;
    border: none;
    background: none;
    -webkit-appearance: none;
    appearance: none;
}

/* Input reset */
input {
    font-family: inherit;
    font-size: inherit;
    border: none;
    background: none;
}

input:focus {
    outline: none;
}

/* Link reset */
a {
    color: inherit;
    text-decoration: none;
}

/* List reset */
ul, ol {
    list-style: none;
}

/* Image reset */
img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ============================================
   App Container
   ============================================ */
#app {
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
}

/* ============================================
   View Management
   ============================================ */
.view {
    display: none;
    flex-direction: column;
    flex: 1;
}

.view.active {
    display: flex;
}

/* ============================================
   Input View
   ============================================ */
#input-view {
    justify-content: center;
    align-items: center;
    padding: var(--space-6);
    padding-top: calc(var(--safe-area-top) + var(--space-6));
    padding-bottom: calc(var(--safe-area-bottom) + var(--space-6));
    background: linear-gradient(180deg, var(--color-primary-light) 0%, var(--color-background) 40%);
    min-height: 100vh;
    min-height: 100dvh;
}

.input-container {
    width: 100%;
    max-width: var(--input-card-max-width);
    display: flex;
    flex-direction: column;
    gap: var(--space-8);
}

/* Logo Section */
.logo-section {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-4);
}

.logo {
    width: 72px;
    height: 72px;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

.app-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.app-subtitle {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    max-width: 280px;
}

/* URL Form */
.url-form {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    background: var(--color-background);
    padding: var(--space-6);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

.input-group {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    background: var(--color-surface);
    border: 2px solid transparent;
    border-radius: var(--radius-lg);
    padding: var(--space-2);
    transition: border-color var(--transition-fast);
}

.input-group:focus-within {
    border-color: var(--color-primary);
}

.input-group.has-error {
    border-color: var(--color-error);
}

#url-input {
    flex: 1;
    padding: var(--space-3) var(--space-4);
    font-size: var(--font-size-base);
    background: transparent;
    color: var(--color-text-primary);
}

#url-input::placeholder {
    color: var(--color-text-tertiary);
}

.paste-btn,
.clear-btn {
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.paste-btn:hover,
.clear-btn:hover {
    background: var(--color-border);
    color: var(--color-text-primary);
}

.paste-btn:active,
.clear-btn:active {
    transform: scale(0.95);
}

.paste-btn svg,
.clear-btn svg {
    width: 20px;
    height: 20px;
}

/* Error Message */
.error-message {
    font-size: var(--font-size-sm);
    color: var(--color-error);
    padding: 0 var(--space-2);
    min-height: 20px;
}

/* Convert Button */
.convert-btn {
    width: 100%;
    padding: var(--space-4) var(--space-6);
    background: var(--color-primary);
    color: white;
    font-size: var(--font-size-base);
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    min-height: 52px;
}

.convert-btn:hover:not(:disabled) {
    background: var(--color-primary-dark);
    box-shadow: var(--shadow-md);
}

.convert-btn:active:not(:disabled) {
    transform: scale(0.98);
}

.convert-btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.btn-loading {
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.spinner {
    width: 20px;
    height: 20px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* Recent URLs */
.recent-urls {
    text-align: center;
}

.recent-title {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-2);
}

#recent-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    justify-content: center;
}

#recent-list li {
    display: flex;
}

#recent-list button {
    font-size: var(--font-size-sm);
    color: var(--color-primary);
    padding: var(--space-2) var(--space-3);
    background: var(--color-primary-light);
    border-radius: var(--radius-full);
    max-width: 200px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    transition: background var(--transition-fast);
}

#recent-list button:hover {
    background: var(--color-border);
}

/* ============================================
   Reading View
   ============================================ */
#reading-view {
    background: var(--color-background);
}

.reading-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    padding-top: var(--safe-area-top);
    background: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-left: var(--space-4);
    padding-right: var(--space-4);
    z-index: 100;
}

.nav-btn,
.action-btn {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-primary);
    border-radius: var(--radius-full);
    transition: background var(--transition-fast);
}

.nav-btn:hover,
.action-btn:hover {
    background: var(--color-surface);
}

.nav-btn svg,
.action-btn svg {
    width: 24px;
    height: 24px;
}

.header-actions {
    display: flex;
    gap: var(--space-1);
}

/* Reading Content */
.reading-content {
    flex: 1;
    padding-top: calc(var(--header-height) + var(--safe-area-top) + var(--space-6));
    padding-bottom: calc(var(--safe-area-bottom) + var(--space-16));
    padding-left: var(--space-6);
    padding-right: var(--space-6);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}

.content-container {
    max-width: var(--content-max-width);
    margin: 0 auto;
}

/* Article Typography */
.content-container h1 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    line-height: var(--line-height-tight);
    margin-bottom: var(--space-6);
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
}

.content-container h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    line-height: var(--line-height-tight);
    margin-top: var(--space-8);
    margin-bottom: var(--space-4);
    color: var(--color-text-primary);
}

.content-container h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    line-height: var(--line-height-tight);
    margin-top: var(--space-6);
    margin-bottom: var(--space-3);
    color: var(--color-text-primary);
}

.content-container h4,
.content-container h5,
.content-container h6 {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-top: var(--space-5);
    margin-bottom: var(--space-2);
}

.content-container p {
    font-size: var(--font-size-md);
    line-height: var(--line-height-loose);
    margin-bottom: var(--space-5);
    color: var(--color-text-primary);
}

.content-container a {
    color: var(--color-primary);
    text-decoration: underline;
    text-underline-offset: 2px;
}

.content-container a:hover {
    color: var(--color-primary-dark);
}

.content-container img {
    width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    margin: var(--space-6) 0;
    background: var(--color-surface);
}

.content-container figure {
    margin: var(--space-6) 0;
}

.content-container figcaption {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    text-align: center;
    margin-top: var(--space-2);
}

.content-container ul,
.content-container ol {
    margin-bottom: var(--space-5);
    padding-left: var(--space-6);
}

.content-container li {
    font-size: var(--font-size-md);
    line-height: var(--line-height-loose);
    margin-bottom: var(--space-2);
}

.content-container ul li {
    list-style-type: disc;
}

.content-container ol li {
    list-style-type: decimal;
}

.content-container blockquote {
    border-left: 4px solid var(--color-primary);
    padding-left: var(--space-5);
    margin: var(--space-6) 0;
    font-style: italic;
    color: var(--color-text-secondary);
}

.content-container pre,
.content-container code {
    font-family: var(--font-family-mono);
    font-size: var(--font-size-sm);
    background: var(--color-surface);
    border-radius: var(--radius-sm);
}

.content-container code {
    padding: var(--space-1) var(--space-2);
}

.content-container pre {
    padding: var(--space-4);
    overflow-x: auto;
    margin: var(--space-5) 0;
}

.content-container pre code {
    padding: 0;
    background: none;
}

.content-container hr {
    border: none;
    height: 1px;
    background: var(--color-border);
    margin: var(--space-8) 0;
}

.content-container table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--space-6) 0;
    font-size: var(--font-size-sm);
}

.content-container th,
.content-container td {
    padding: var(--space-3) var(--space-4);
    text-align: left;
    border: 1px solid var(--color-border);
}

.content-container th {
    background: var(--color-surface);
    font-weight: 600;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: calc(var(--safe-area-bottom) + var(--space-6));
    right: var(--space-6);
    width: 48px;
    height: 48px;
    background: var(--color-text-primary);
    color: white;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    z-index: 50;
}

.back-to-top:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

.back-to-top svg {
    width: 24px;
    height: 24px;
}

/* ============================================
   Error View
   ============================================ */
#error-view {
    justify-content: center;
    align-items: center;
    padding: var(--space-6);
}

.error-container {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-4);
    max-width: 320px;
}

.error-icon {
    width: 80px;
    height: 80px;
    color: var(--color-error);
}

.error-icon svg {
    width: 100%;
    height: 100%;
}

.error-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
}

.error-text {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    line-height: var(--line-height-relaxed);
}

.error-actions {
    display: flex;
    gap: var(--space-3);
    margin-top: var(--space-4);
}

.retry-btn {
    padding: var(--space-3) var(--space-6);
    background: var(--color-primary);
    color: white;
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: background var(--transition-fast);
}

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

.back-to-input-btn {
    padding: var(--space-3) var(--space-6);
    color: var(--color-primary);
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: background var(--transition-fast);
}

.back-to-input-btn:hover {
    background: var(--color-primary-light);
}

/* ============================================
   Loading Overlay
   ============================================ */
.loading-overlay {
    position: fixed;
    inset: 0;
    background: var(--color-overlay);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 200;
    backdrop-filter: blur(4px);
}

.loading-content {
    background: var(--color-background);
    padding: var(--space-8);
    border-radius: var(--radius-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-4);
    box-shadow: var(--shadow-xl);
}

.loading-spinner {
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
}

.loading-text {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
}

/* ============================================
   Install Prompt
   ============================================ */
.install-prompt {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    padding: var(--space-4);
    padding-bottom: calc(var(--space-4) + var(--safe-area-bottom));
    background: var(--color-background);
    border-top: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
    z-index: 150;
}

.install-content {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}

.install-content p {
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    text-align: center;
}

.install-actions {
    display: flex;
    gap: var(--space-3);
}

.install-yes-btn {
    flex: 1;
    padding: var(--space-3) var(--space-5);
    background: var(--color-primary);
    color: white;
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: background var(--transition-fast);
}

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

.install-no-btn {
    flex: 1;
    padding: var(--space-3) var(--space-5);
    color: var(--color-text-secondary);
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: background var(--transition-fast);
}

.install-no-btn:hover {
    background: var(--color-surface);
}

/* ============================================
   Offline Banner
   ============================================ */
.offline-banner {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    padding-top: var(--safe-area-top);
    background: var(--color-error);
    color: white;
    padding: var(--space-3) var(--space-4);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    font-size: var(--font-size-sm);
    font-weight: 500;
    z-index: 300;
}

.offline-banner svg {
    width: 18px;
    height: 18px;
}

/* ============================================
   Utility Classes
   ============================================ */
.hidden {
    display: none !important;
}

/* ============================================
   Responsive Breakpoints
   ============================================ */

/* Tablet */
@media (min-width: 480px) {
    .app-title {
        font-size: var(--font-size-3xl);
    }
    
    .reading-content {
        padding-left: var(--space-8);
        padding-right: var(--space-8);
    }
}

/* Desktop */
@media (min-width: 768px) {
    #input-view {
        padding: var(--space-12);
    }
    
    .input-container {
        gap: var(--space-10);
    }
    
    .url-form {
        padding: var(--space-8);
    }
    
    .content-container {
        padding-top: var(--space-8);
    }
    
    .content-container h1 {
        font-size: var(--font-size-3xl);
    }
    
    .content-container h2 {
        font-size: var(--font-size-2xl);
    }
}

/* Large Desktop */
@media (min-width: 1024px) {
    .input-container {
        gap: var(--space-12);
    }
    
    .logo {
        width: 88px;
        height: 88px;
    }
}

/* High contrast mode */
@media (prefers-contrast: high) {
    :root {
        --color-text-primary: #000000;
        --color-text-secondary: #333333;
        --color-border: #000000;
    }
    
    .convert-btn,
    .retry-btn,
    .install-yes-btn {
        border: 2px solid currentColor;
    }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* Dark mode support (if user prefers dark) */
@media (prefers-color-scheme: dark) {
    /* Optional: Add dark mode styles here if needed */
}