/* ============================================
   RESET & BASE (Mobile-First)
   ============================================ */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colors */
    --color-primary: #7cffcb;
    --color-primary-dark: #58c7b8;
    --color-bg-dark: #0a0a0a;
    --color-bg-medium: #1a1a2e;
    --color-bg-light: #16213e;
    --color-bg-lighter: #0f3460;
    --color-text: #ffffff;
    --color-text-secondary: #7cffcb;
    
    /* Spacing (Mobile base) */
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    
    /* Typography (Fluid) */
    --font-size-xs: clamp(0.625rem, 0.5rem + 0.5vw, 0.75rem);
    --font-size-sm: clamp(0.75rem, 0.65rem + 0.5vw, 0.875rem);
    --font-size-base: clamp(0.875rem, 0.8rem + 0.5vw, 1rem);
    --font-size-md: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
    --font-size-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
    --font-size-xl: clamp(1.25rem, 1.1rem + 1vw, 1.75rem);
    
    /* Touch targets */
    --touch-target-min: 44px;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Borders */
    --border-radius-sm: 0.5rem;
    --border-radius-md: 0.75rem;
    --border-radius-lg: 1rem;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Roboto Mono', monospace;
    background: linear-gradient(135deg, var(--color-bg-dark) 0%, var(--color-bg-medium) 100%);
    color: var(--color-text);
    min-height: 100vh;
    overflow-x: hidden;
    overflow-y: auto;
}

/* ============================================
   HEADER (Mobile-First)
   ============================================ */
header {
    background: linear-gradient(135deg, var(--color-bg-light) 0%, var(--color-bg-lighter) 100%);
    color: var(--color-text);
    padding: var(--space-md) var(--space-md);
    text-align: center;
    font-size: var(--font-size-lg);
    font-weight: 700;
    box-shadow: 0 0.25rem 1rem rgba(0, 0, 0, 0.4);
    letter-spacing: 0.05em;
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(124, 255, 203, 0.1), transparent);
    animation: shine 3s infinite;
}

@keyframes shine {
    0% { left: -100%; }
    100% { left: 100%; }
}

/* ============================================
   TOOLBAR (Mobile-First)
   ============================================ */
.toolbar {
    background: linear-gradient(135deg, var(--color-bg-medium) 0%, var(--color-bg-light) 100%);
    padding: var(--space-sm);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    box-shadow: 0 0.25rem 1rem rgba(0, 0, 0, 0.3);
    border-bottom: 2px solid rgba(124, 255, 203, 0.1);
}

.toolbar-group {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
}

.toolbar-btn {
    /* Touch-friendly sizing */
    min-height: var(--touch-target-min);
    padding: var(--space-sm) var(--space-md);
    
    /* Visual */
    background: linear-gradient(135deg, var(--color-bg-lighter) 0%, var(--color-bg-light) 100%);
    color: var(--color-primary);
    border: 2px solid rgba(124, 255, 203, 0.2);
    border-radius: var(--border-radius-sm);
    
    /* Typography */
    font-size: var(--font-size-sm);
    font-family: 'Roboto Mono', monospace;
    font-weight: 600;
    
    /* Layout */
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
    
    /* Interaction */
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
    
    /* Accessibility */
    -webkit-tap-highlight-color: transparent;
}

/* Primary button (Download) */
.toolbar-btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-bg-dark);
    border-color: var(--color-primary);
    font-weight: 700;
}

.toolbar-btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 0.5rem 1.5rem rgba(124, 255, 203, 0.4);
}

/* Secondary buttons */
.toolbar-btn-secondary {
    background: linear-gradient(135deg, var(--color-bg-lighter) 0%, var(--color-bg-light) 100%);
    color: var(--color-primary);
}

/* Button icons */
.btn-icon {
    flex-shrink: 0;
}

/* Hide text on mobile for some buttons */
.btn-text-desktop {
    display: none;
}

/* Active state (touch & mouse) */
.toolbar-btn:active,
.toolbar-btn.active {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-bg-dark);
    border-color: var(--color-primary);
    box-shadow: 0 0.25rem 1rem rgba(124, 255, 203, 0.4);
    transform: scale(0.98);
}

/* Focus for accessibility */
.toolbar-btn:focus-visible {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
}

.responsive-buttons {
    display: flex;
    gap: var(--space-xs);
    background: rgba(0, 0, 0, 0.2);
    padding: var(--space-xs);
    border-radius: var(--border-radius-md);
    width: 100%;
}

.responsive-buttons .toolbar-btn {
    flex: 1;
    min-width: 0;
    padding: var(--space-sm);
}

/* ============================================
   CONTAINER (Mobile-First)
   ============================================ */
.container {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
    padding: var(--space-md);
    min-height: calc(100vh - 10rem);
}

/* ============================================
   EDITOR & PREVIEW WRAPPERS (Mobile-First)
   ============================================ */
.editor-wrapper,
.preview-wrapper {
    flex: 1;
    min-height: 20rem;
    border-radius: var(--border-radius-md);
    border: 2px solid rgba(124, 255, 203, 0.2);
    overflow: hidden;
    box-shadow: 0 0.5rem 2rem rgba(0, 0, 0, 0.4);
    background: rgba(26, 26, 46, 0.6);
    backdrop-filter: blur(10px);
    position: relative;
    transition: all var(--transition-base);
}

/* Touch feedback */
.editor-wrapper:active,
.preview-wrapper:active {
    border-color: rgba(124, 255, 203, 0.4);
}

.editor-wrapper {
    display: flex;
    flex-direction: column;
}

/* Labels */
.editor-wrapper::before,
.preview-wrapper::before {
    position: absolute;
    top: var(--space-sm);
    left: var(--space-sm);
    color: var(--color-primary);
    font-size: var(--font-size-xs);
    font-weight: 700;
    z-index: 10;
    background: rgba(15, 52, 96, 0.9);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--border-radius-sm);
    letter-spacing: 0.05em;
    pointer-events: none;
}

.editor-wrapper::before {
    content: '📝 Editor';
}

.preview-wrapper::before {
    content: '👁️ Preview';
}

.preview-wrapper::before {
    content: '👁️ Preview';
    position: absolute;
    top: var(--space-sm);
    left: var(--space-sm);
    color: var(--color-primary);
    font-size: var(--font-size-xs);
    font-weight: 700;
    z-index: 10;
    background: rgba(15, 52, 96, 0.9);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--border-radius-sm);
    letter-spacing: 0.05em;
    pointer-events: none;
}

/* Empty State */
.empty-state {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    z-index: 5;
    max-width: 90%;
    padding: var(--space-lg);
    pointer-events: none;
}

.empty-state.hidden {
    display: none;
}

.empty-state-icon {
    color: rgba(124, 255, 203, 0.3);
    margin-bottom: var(--space-md);
}

.empty-state-title {
    color: var(--color-primary);
    font-size: var(--font-size-lg);
    font-weight: 700;
    margin-bottom: var(--space-sm);
}

.empty-state-text {
    color: rgba(255, 255, 255, 0.6);
    font-size: var(--font-size-sm);
    margin-bottom: var(--space-lg);
    line-height: 1.5;
}

.btn-example {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-bg-dark);
    border: none;
    border-radius: var(--border-radius-sm);
    padding: var(--space-sm) var(--space-lg);
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    transition: all var(--transition-base);
    pointer-events: auto;
    font-family: 'Roboto Mono', monospace;
}

.btn-example:hover {
    transform: translateY(-2px);
    box-shadow: 0 0.5rem 1.5rem rgba(124, 255, 203, 0.4);
}

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

/* ============================================
   CODEMIRROR (Mobile-First)
   ============================================ */
textarea {
    width: 100%;
    height: 100%;
    padding: var(--space-md);
    background-color: #000;
    color: var(--color-primary);
    font-size: var(--font-size-sm);
    border: none;
    resize: none;
    font-family: 'Roboto Mono', monospace;
}

.CodeMirror {
    height: 100% !important;
    font-size: var(--font-size-sm) !important;
    font-family: 'Roboto Mono', monospace;
}

/* ============================================
   PREVIEW IFRAME (Mobile-First)
   ============================================ */
.preview-wrapper {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    background: linear-gradient(135deg, var(--color-bg-dark) 0%, var(--color-bg-medium) 100%);
    padding: 3rem var(--space-md) var(--space-md);
    overflow: auto;
    -webkit-overflow-scrolling: touch;
}

iframe {
    width: 100%;
    height: 100%;
    min-height: 20rem;
    background-color: #fff;
    border: none;
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-slow);
    box-shadow: 0 0.625rem 2.5rem rgba(0, 0, 0, 0.5);
}

/* Preview modes - only apply on larger screens */
iframe.tablet,
iframe.mobile {
    width: 100%;
    height: 100%;
}

/* ============================================
   FOOTER (Mobile-First)
   ============================================ */
footer {
    position: relative;
    text-align: center;
    color: var(--color-primary);
    font-size: var(--font-size-xs);
    font-weight: 600;
    background: rgba(15, 52, 96, 0.8);
    padding: var(--space-sm) var(--space-md);
    margin: var(--space-md);
    border-radius: var(--border-radius-sm);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(124, 255, 203, 0.2);
    box-shadow: 0 0.25rem 1rem rgba(0, 0, 0, 0.3);
    letter-spacing: 0.05em;
}

/* ============================================
   TABLET (640px+)
   ============================================ */
@media screen and (min-width: 40rem) {
    :root {
        --space-xs: 0.625rem;
        --space-sm: 1rem;
        --space-md: 1.25rem;
        --space-lg: 2rem;
        --space-xl: 3rem;
    }
    
    header {
        padding: var(--space-lg) var(--space-xl);
    }
    
    .toolbar {
        flex-direction: row;
        flex-wrap: wrap;
        align-items: center;
        justify-content: space-between;
        padding: var(--space-md) var(--space-lg);
    }
    
    .toolbar-group {
        flex: 0 0 auto;
    }
    
    .toolbar-btn {
        width: auto;
        min-width: auto;
    }
    
    .btn-text-desktop {
        display: inline;
    }
    
    .responsive-buttons {
        flex: 0 1 auto;
        width: auto;
    }
    
    .container {
        padding: var(--space-lg);
        gap: var(--space-lg);
    }
    
    .editor-wrapper,
    .preview-wrapper {
        min-height: 25rem;
    }
    
    /* Hover effects only on devices that support it */
    @media (hover: hover) and (pointer: fine) {
        .toolbar-btn::before {
            content: '';
            position: absolute;
            top: 50%;
            left: 50%;
            width: 0;
            height: 0;
            border-radius: 50%;
            background: rgba(124, 255, 203, 0.2);
            transform: translate(-50%, -50%);
            transition: width 0.6s, height 0.6s;
        }
        
        .toolbar-btn:hover::before {
            width: 18.75rem;
            height: 18.75rem;
        }
        
        .toolbar-btn-secondary:hover {
            background: linear-gradient(135deg, var(--color-bg-light) 0%, var(--color-bg-lighter) 100%);
            border-color: var(--color-primary);
            transform: translateY(-2px);
            box-shadow: 0 0.375rem 1.25rem rgba(124, 255, 203, 0.3);
        }
        
        .editor-wrapper:hover,
        .preview-wrapper:hover {
            border-color: rgba(124, 255, 203, 0.5);
            box-shadow: 0 0.75rem 2.5rem rgba(124, 255, 203, 0.2);
            transform: translateY(-2px);
        }
    }
    
    footer {
        position: fixed;
        left: var(--space-lg);
        bottom: var(--space-lg);
        margin: 0;
    }
}

/* ============================================
   DESKTOP (1024px+)
   ============================================ */
@media screen and (min-width: 64rem) {
    :root {
        --space-xs: 0.75rem;
        --space-sm: 1rem;
        --space-md: 1.5rem;
        --space-lg: 2.5rem;
        --space-xl: 4rem;
    }
    
    .toolbar {
        flex-wrap: nowrap;
        padding: var(--space-md) var(--space-xl);
    }
    
    .container {
        flex-direction: row;
        height: calc(100vh - 10rem);
        padding: var(--space-lg);
        gap: var(--space-lg);
    }
    
    .editor-wrapper,
    .preview-wrapper {
        min-height: auto;
        height: 100%;
    }
    
    /* Enable preview size modes on desktop */
    iframe.tablet {
        width: 48rem;
        height: 64rem;
        box-shadow: 0 1rem 3rem rgba(124, 255, 203, 0.2);
    }
    
    iframe.mobile {
        width: 23.4375rem;
        height: 41.6875rem;
        box-shadow: 0 1rem 3rem rgba(124, 255, 203, 0.2);
    }
}

/* ============================================
   LARGE DESKTOP (1440px+)
   ============================================ */
@media screen and (min-width: 90rem) {
    header {
        font-size: var(--font-size-xl);
    }
    
    .toolbar-btn {
        font-size: var(--font-size-base);
    }
    
    .CodeMirror {
        font-size: var(--font-size-base) !important;
    }
}

/* ============================================
   LANDSCAPE MOBILE (Height < 600px)
   ============================================ */
@media screen and (max-height: 37.5rem) and (orientation: landscape) {
    header {
        padding: var(--space-sm) var(--space-md);
    }
    
    .toolbar {
        padding: var(--space-xs) var(--space-md);
    }
    
    .container {
        flex-direction: row;
        height: calc(100vh - 7rem);
        padding: var(--space-sm);
        gap: var(--space-sm);
    }
    
    .editor-wrapper,
    .preview-wrapper {
        min-height: auto;
        height: 100%;
    }
    
    footer {
        display: none;
    }
}

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

/* High contrast mode */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #00ff00;
    }
    
    .toolbar-btn,
    .editor-wrapper,
    .preview-wrapper {
        border-width: 3px;
    }
}

/* ============================================
   PRINT
   ============================================ */
@media print {
    header,
    .toolbar,
    footer {
        display: none;
    }
    
    .container {
        flex-direction: column;
        height: auto;
    }
    
    .editor-wrapper,
    .preview-wrapper {
        page-break-inside: avoid;
    }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}