:root {
    --bg: #F4F4F0;
    --fg: #111111;
    --fg-muted: #555555;
    --border: #111111;
    --accent: #CCFF00; /* Neon highlighter yellow */
    --accent-hover: #B3E600;
    --card-bg: #FFFFFF;
    --error: #FF3366;
    
    --font-sans: 'Lexend', sans-serif;
    --font-mono: 'DM Mono', monospace;
    
    --shadow: 4px 4px 0px 0px var(--fg);
    --shadow-hover: 6px 6px 0px 0px var(--fg);
    --shadow-active: 2px 2px 0px 0px var(--fg);
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg);
    color: var(--fg);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem 1rem;
    position: relative;
    /* Notebook dot grid */
    background-image: radial-gradient(var(--fg-muted) 1px, transparent 1px);
    background-size: 24px 24px;
    background-position: 0 0;
}

.app-container {
    background: var(--card-bg);
    border: 3px solid var(--border);
    width: 100%;
    max-width: 600px;
    padding: 2.5rem;
    box-shadow: var(--shadow);
    border-radius: 4px;
}

.app-header {
    margin-bottom: 2.5rem;
}

.tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    background: var(--fg);
    color: var(--bg);
    padding: 0.25rem 0.5rem;
    margin-bottom: 1rem;
    letter-spacing: 0.05em;
}

.app-header h1 {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 0.5rem;
    letter-spacing: -0.03em;
}

.app-header p {
    font-family: var(--font-mono);
    color: var(--fg-muted);
    font-size: 0.9rem;
    line-height: 1.5;
}

.tabs {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
    margin-bottom: 2rem;
}

@media (max-width: 480px) {
    .tabs {
        grid-template-columns: 1fr;
    }
}

.tab-btn {
    background: var(--bg);
    border: 2px solid var(--border);
    color: var(--fg);
    font-family: var(--font-sans);
    font-weight: 600;
    font-size: 0.9rem;
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: all 0.15s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: 2px 2px 0px 0px var(--fg);
}

.tab-btn:hover {
    transform: translate(-1px, -1px);
    box-shadow: 3px 3px 0px 0px var(--fg);
}

.tab-btn:active {
    transform: translate(2px, 2px);
    box-shadow: 0px 0px 0px 0px var(--fg);
}

.tab-btn.active {
    background: var(--accent);
}

.upload-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.drop-zone {
    border: 3px dashed var(--border);
    background: var(--bg);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.drop-zone:hover {
    background: #E8E8E4;
}

.drop-zone.dragover {
    background: var(--accent);
    border-style: solid;
    transform: scale(1.02);
}

.drop-icon-wrapper {
    margin-bottom: 1rem;
    display: inline-block;
    padding: 0.75rem;
    background: var(--card-bg);
    border: 2px solid var(--border);
    box-shadow: 2px 2px 0px 0px var(--fg);
}

.drop-zone h2 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.drop-zone p {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--fg-muted);
}

.file-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    border: 2px solid var(--border);
    padding: 0.75rem 1rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 500;
    box-shadow: 2px 2px 0px 0px var(--fg);
}

.remove-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--fg);
    font-family: var(--font-sans);
    font-weight: 700;
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    cursor: pointer;
    transition: all 0.1s ease;
}

.remove-btn:hover {
    background: var(--error);
    color: white;
}

.process-btn {
    width: 100%;
    background: var(--fg);
    color: var(--card-bg);
    border: 2px solid var(--border);
    padding: 1.25rem;
    font-family: var(--font-sans);
    font-weight: 700;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.15s ease;
    box-shadow: var(--shadow);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.process-btn:hover:not(:disabled) {
    transform: translate(-2px, -2px);
    box-shadow: var(--shadow-hover);
    background: var(--accent);
    color: var(--fg);
}

.process-btn:active:not(:disabled) {
    transform: translate(4px, 4px);
    box-shadow: 0px 0px 0px 0px var(--fg);
}

.process-btn:disabled {
    background: #DDDDDD;
    color: #888888;
    border-color: #AAAAAA;
    box-shadow: none;
    cursor: not-allowed;
    transform: none;
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 2rem;
    border: 2px solid var(--border);
    background: var(--accent);
}

.spinner {
    width: 32px;
    height: 32px;
    border: 4px solid var(--fg);
    border-right-color: transparent;
    border-radius: 50%;
    animation: spin 0.75s linear infinite;
}

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

.loading p {
    font-family: var(--font-mono);
    font-weight: 500;
    font-size: 0.9rem;
}

.hidden {
    display: none !important;
}

.error-msg {
    background: var(--error);
    color: white;
    border: 2px solid var(--border);
    padding: 1rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 500;
    box-shadow: 2px 2px 0px 0px var(--fg);
}

.app-footer {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 2px solid var(--border);
    text-align: center;
}

.app-footer p {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--fg-muted);
}