/* =============================================================================
   CSS Variables - Dark Theme
   ============================================================================= */

:root {
    /* Colors */
    --color-bg-primary: #0d1117;
    --color-bg-secondary: #161b22;
    --color-bg-tertiary: #21262d;
    --color-bg-hover: #30363d;
    
    --color-border: #30363d;
    --color-border-light: #21262d;
    
    --color-text-primary: #e6edf3;
    --color-text-secondary: #8b949e;
    --color-text-muted: #6e7681;
    
    --color-accent: #58a6ff;
    --color-accent-hover: #79b8ff;
    --color-accent-bg: rgba(88, 166, 255, 0.1);
    
    --color-success: #3fb950;
    --color-success-bg: rgba(63, 185, 80, 0.1);
    
    --color-error: #f85149;
    --color-error-bg: rgba(248, 81, 73, 0.1);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
    
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --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);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.6);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
}

/* =============================================================================
   Reset & Base Styles
   ============================================================================= */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    min-height: 100vh;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-accent-hover);
}

/* =============================================================================
   Layout
   ============================================================================= */

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-lg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.main {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

/* =============================================================================
   Header
   ============================================================================= */

.header {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-primary);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    text-decoration: none;
    transition: opacity var(--transition-fast);
}

.logo:hover {
    opacity: 0.9;
    color: var(--color-text-primary);
}

.logo-icon {
    font-size: var(--font-size-3xl);
}

.tagline {
    color: var(--color-text-secondary);
    margin-top: var(--spacing-sm);
    font-size: var(--font-size-lg);
}

/* =============================================================================
   Cards
   ============================================================================= */

.editor-card,
.view-card,
.error-card {
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.editor-header,
.view-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-light);
    background-color: var(--color-bg-tertiary);
}

.editor-title,
.view-title {
    font-weight: 600;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.editor-actions,
.view-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.editor-textarea {
    width: 100%;
    min-height: 350px;
    padding: var(--spacing-lg);
    background-color: var(--color-bg-secondary);
    border: none;
    color: var(--color-text-primary);
    font-family: var(--font-mono);
    font-size: var(--font-size-base);
    line-height: 1.7;
    resize: vertical;
    outline: none;
}

.editor-textarea::placeholder {
    color: var(--color-text-muted);
}

.editor-footer,
.view-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    border-top: 1px solid var(--color-border-light);
    background-color: var(--color-bg-tertiary);
}

.editor-footer-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.char-count,
.text-meta {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}

.expiration-select {
    background-color: var(--color-bg-secondary);
    color: var(--color-text-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.expiration-select:hover {
    border-color: var(--color-accent);
}

.expiration-select:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-bg);
}

/* =============================================================================
   View Content
   ============================================================================= */

.view-content {
    padding: var(--spacing-lg);
    max-height: 60vh;
    overflow: auto;
}

.text-display {
    font-family: var(--font-mono);
    font-size: var(--font-size-base);
    line-height: 1.7;
    white-space: pre-wrap;
    word-wrap: break-word;
    color: var(--color-text-primary);
    margin: 0;
}

/* =============================================================================
   Buttons
   ============================================================================= */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-family: var(--font-family);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background-color: var(--color-accent);
    color: #ffffff;
    border-color: var(--color-accent);
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #ffffff;
}

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

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-bg-hover);
}

.btn-ghost {
    background-color: transparent;
    color: var(--color-text-secondary);
    border-color: transparent;
    padding: var(--spacing-sm);
}

.btn-ghost:hover:not(:disabled) {
    background-color: var(--color-bg-hover);
    color: var(--color-text-primary);
}

.btn-icon {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
    border-color: var(--color-border);
    padding: var(--spacing-sm);
    width: 40px;
    height: 40px;
}

.btn-icon:hover:not(:disabled) {
    background-color: var(--color-bg-hover);
    color: var(--color-text-primary);
}

/* =============================================================================
   Modal
   ============================================================================= */

.modal {
    position: fixed;
    inset: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
}

.modal.hidden {
    display: none;
}

.modal-backdrop {
    position: absolute;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
}

.modal-content {
    position: relative;
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    width: 100%;
    max-width: 480px;
    animation: modalIn var(--transition-base);
}

@keyframes modalIn {
    from {
        opacity: 0;
        transform: scale(0.95) translateY(-10px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-light);
}

.modal-title {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.success-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background-color: var(--color-success-bg);
    color: var(--color-success);
    border-radius: 50%;
    font-size: var(--font-size-sm);
}

.modal-body {
    padding: var(--spacing-lg);
}

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

.link-box {
    display: flex;
    gap: var(--spacing-sm);
}

.share-link-input {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    outline: none;
}

.share-link-input:focus {
    border-color: var(--color-accent);
}

.copy-feedback {
    color: var(--color-success);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-sm);
}

.copy-feedback.hidden {
    display: none;
}

.modal-footer {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    border-top: 1px solid var(--color-border-light);
    justify-content: flex-end;
}

/* =============================================================================
   Error Page
   ============================================================================= */

.error-card {
    text-align: center;
    padding: var(--spacing-2xl);
}

.error-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
}

.error-title {
    font-size: 5rem;
    font-weight: 700;
    color: var(--color-text-muted);
    line-height: 1;
    margin-bottom: var(--spacing-md);
}

.error-message {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

.error-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 400px;
    margin-left: auto;
    margin-right: auto;
}

/* =============================================================================
   Footer
   ============================================================================= */

.footer {
    text-align: center;
    padding: var(--spacing-xl) 0;
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}

/* =============================================================================
   Loading State
   ============================================================================= */

.btn.loading {
    position: relative;
    color: transparent;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 18px;
    height: 18px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* =============================================================================
   Responsive Design
   ============================================================================= */

@media (max-width: 640px) {
    .container {
        padding: var(--spacing-md);
    }
    
    .header {
        padding: var(--spacing-lg) 0;
    }
    
    .logo {
        font-size: var(--font-size-xl);
    }
    
    .tagline {
        font-size: var(--font-size-base);
    }
    
    .editor-header,
    .view-header,
    .editor-footer,
    .view-footer {
        padding: var(--spacing-sm) var(--spacing-md);
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .editor-textarea {
        min-height: 250px;
        padding: var(--spacing-md);
    }
    
    .view-content {
        padding: var(--spacing-md);
    }
    
    .modal-content {
        max-width: 100%;
    }
    
    .modal-footer {
        flex-direction: column;
    }
    
    .modal-footer .btn {
        width: 100%;
    }
}

/* =============================================================================
   Scrollbar Styling
   ============================================================================= */

::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background-color: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
    background-color: var(--color-bg-hover);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background-color: var(--color-text-muted);
}

/* Firefox */
* {
    scrollbar-width: thin;
    scrollbar-color: var(--color-bg-hover) var(--color-bg-secondary);
}

/* =============================================================================
   Selection
   ============================================================================= */

::selection {
    background-color: var(--color-accent);
    color: #ffffff;
}