:root {
    /* Default Light Theme */
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --drop-zone-border: #cbd5e1;
    --drop-zone-active: #2563eb;
    --container-width: 800px;
    --radius-lg: 1rem;
    --radius-md: 0.5rem;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --crt-overlay: transparent;
    --code-bg: #f1f5f9;
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --drop-zone-border: #475569;
    --drop-zone-active: #3b82f6;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3);
    --primary-color: #3b82f6;
    --primary-hover: #60a5fa;
    --code-bg: #0f172a;
}

[data-theme="vt320"] {
    --primary-color: #ffb000;
    --primary-hover: #ffcc00;
    --bg-color: #0a0a0a;
    --card-bg: #000000;
    --text-color: #ffb000;
    --text-muted: #aa7700;
    --border-color: #ffb000;
    --drop-zone-border: #ffb000;
    --drop-zone-active: #ffcc00;
    --shadow: 0 0 10px rgba(255, 176, 0, 0.2);
    --radius-lg: 0;
    --radius-md: 0;
    --crt-overlay: linear-gradient(rgba(18, 16, 16, 0) 50%, rgba(0, 0, 0, 0.25) 50%), linear-gradient(90deg, rgba(255, 0, 0, 0.06), rgba(0, 255, 0, 0.02), rgba(0, 0, 255, 0.06));
    --code-bg: #000000;
}

[data-theme="vt320"] body {
    font-family: 'Courier New', Courier, monospace;
    text-shadow: 0 0 5px rgba(255, 176, 0, 0.7);
}

[data-theme="vt320"] .btn.secondary {
    background-color: transparent;
    color: var(--primary-color);
    border-color: var(--primary-color);
}

[data-theme="vt320"] .markdown-body pre {
    border: 1px solid var(--primary-color);
}

[data-theme="vt320"] .upload-icon {
    color: var(--primary-color);
}

[data-theme="vt320"] header h2 {
    color: var(--primary-color);
}

/* CRT Scanline Effect */
body::after {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--crt-overlay);
    background-size: 100% 4px, 3px 100%;
    pointer-events: none;
    z-index: 1000;
    opacity: 0.15;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 2rem 0;
}

/* Accessibility */
.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;
}

/* Theme Switcher Styling */
.theme-switcher {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    display: flex;
    gap: 0.5rem;
    background: var(--card-bg);
    padding: 0.5rem;
    border-radius: 2rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    z-index: 1001;
}

.theme-btn {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    border: none;
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.theme-btn:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}

.theme-btn.active {
    background: var(--primary-color);
    color: white;
}

/* Views & State Management */
.view {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.mode-upload #upload-view { display: block; }
.mode-viewer #viewer-view { display: block; }

/* Upload View Styling */
header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 3rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-muted);
    font-size: 1.125rem;
}

.drop-zone {
    background: var(--card-bg);
    border: 3px dashed var(--drop-zone-border);
    border-radius: var(--radius-lg);
    padding: 4rem 2rem;
    text-align: center;
    transition: all 0.2s ease;
    cursor: pointer;
    box-shadow: var(--shadow);
}

.drop-zone.active {
    border-color: var(--drop-zone-active);
    background: #eff6ff;
    transform: scale(1.02);
}

.drop-zone-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.upload-icon {
    width: 4rem;
    height: 4rem;
    color: var(--text-muted);
}

.divider {
    color: var(--text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Viewer View Styling */
.viewer-controls {
    position: sticky;
    top: 0;
    background: var(--bg-color);
    backdrop-filter: blur(8px);
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    z-index: 10;
    display: flex;
    justify-content: center;
}

[data-theme="dark"] .viewer-controls {
    background: rgba(15, 23, 42, 0.8);
}

[data-theme="vt320"] .viewer-controls {
    background: var(--bg-color);
    backdrop-filter: none;
}

.markdown-body {
    background: var(--card-bg);
    padding: 3rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    margin-top: 2rem;
    margin-bottom: 4rem;
}

/* Common Components */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    font-size: 1rem;
}

.btn.primary {
    background-color: var(--primary-color);
    color: white;
}

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

.btn.secondary {
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

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

[data-theme="dark"] .btn.secondary {
    background-color: #334155;
    color: #ffffff;
    border-color: #475569;
}

[data-theme="dark"] .btn.secondary:hover {
    background-color: #475569;
}

[data-theme="vt320"] .btn.secondary {
    background-color: #000000;
    color: #ffb000;
    border: 1px solid #ffb000;
}

[data-theme="vt320"] .btn.secondary:hover {
    background-color: #ffb000;
    color: #000000;
}

.icon {
    width: 1.25rem;
    height: 1.25rem;
}

/* Markdown Typography (GitHub-ish) */
.markdown-body h1, .markdown-body h2 { border-bottom: 1px solid var(--border-color); padding-bottom: 0.3em; margin-top: 1.5em; margin-bottom: 1rem; }
.markdown-body h1 { font-size: 2.25rem; }
.markdown-body h2 { font-size: 1.75rem; }
.markdown-body p { margin-bottom: 1rem; }
.markdown-body code { background: var(--code-bg); color: var(--text-color); padding: 0.2rem 0.4rem; border-radius: 4px; font-family: monospace; }
.markdown-body pre { background: var(--code-bg); color: var(--text-color); padding: 1.5rem; border-radius: var(--radius-md); overflow-x: auto; margin-bottom: 1rem; border: 1px solid var(--border-color); }
.markdown-body pre code { background: transparent; color: inherit; padding: 0; }
.markdown-body ul, .markdown-body ol { margin-bottom: 1rem; padding-left: 2rem; }
.markdown-body blockquote { border-left: 4px solid var(--border-color); padding-left: 1rem; color: var(--text-muted); font-style: italic; margin-bottom: 1rem; }
.markdown-body img { max-width: 100%; border-radius: var(--radius-md); }

/* Responsive adjustments */
@media (max-width: 640px) {
    header h1 { font-size: 2rem; }
    .markdown-body { padding: 1.5rem; border-radius: 0; }
    .container { width: 100%; padding: 1rem; }
    .drop-zone { padding: 2rem 1rem; }
}