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

:root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #252525;
    --bg-tertiary: #2f2f2f;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0a0;
    --accent: #ff6b6b;
    --accent-hover: #ff5252;
    --border: #3a3a3a;
    --success: #51cf66;
    --error: #ff6b6b;
    --warning: #ffd93d;
}

body {
    font-family: 'Monaco', 'Consolas', 'Courier New', monospace;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

header {
    background-color: var(--bg-secondary);
    padding: 1rem 2rem;
    border-bottom: 2px solid var(--accent);
    text-align: center;
}

header h1 {
    color: var(--accent);
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: 0.1em;
}

.tagline {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.25rem;
}

main {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: 1fr 1fr;
    gap: 1px;
    background-color: var(--border);
    overflow: hidden;
}

.panel {
    background-color: var(--bg-secondary);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.output-panel {
    grid-column: 1;
    grid-row: 1;
}

.stack-panel {
    grid-column: 2;
    grid-row: 1;
}

.input-panel {
    grid-column: 1 / -1;
    grid-row: 2;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1rem;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border);
}

.panel-header h2 {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
}

.panel-content {
    flex: 1;
    overflow-y: auto;
    padding: 1rem;
}

/* Output */
.output-line {
    padding: 0.25rem 0;
    font-family: inherit;
    font-size: 0.9rem;
}

.welcome {
    color: var(--text-secondary);
}

.welcome h2 {
    color: var(--accent);
    margin-bottom: 0.5rem;
}

.welcome p {
    margin-bottom: 0.5rem;
}

.welcome .subtitle {
    font-style: italic;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.welcome .examples {
    background-color: var(--bg-tertiary);
    padding: 1rem;
    border-radius: 4px;
    margin: 1rem 0;
}

.welcome .examples h3 {
    color: var(--success);
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
}

.welcome .examples code {
    color: var(--warning);
    background-color: var(--bg-primary);
    padding: 0.2rem 0.4rem;
    border-radius: 2px;
    font-size: 0.85rem;
}

.welcome .hint {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-style: italic;
    margin-top: 1rem;
}

.empty {
    color: var(--text-secondary);
    font-style: italic;
    text-align: center;
    padding: 2rem;
}

/* Stack */
.stack-item {
    display: flex;
    align-items: center;
    padding: 0.5rem;
    margin-bottom: 0.25rem;
    background-color: var(--bg-tertiary);
    border-radius: 4px;
    font-size: 0.9rem;
}

.stack-item .index {
    color: var(--text-secondary);
    margin-right: 1rem;
    min-width: 30px;
    font-weight: 600;
}

.stack-item .value {
    color: var(--success);
    flex: 1;
    word-break: break-all;
}

/* Input */
.input-area {
    flex: 1;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border: none;
    padding: 1rem;
    font-family: inherit;
    font-size: 0.95rem;
    resize: none;
    outline: none;
}

.input-area::placeholder {
    color: var(--text-secondary);
    opacity: 0.5;
}

.button-group {
    display: flex;
    gap: 0.5rem;
    padding: 1rem;
    background-color: var(--bg-tertiary);
    border-top: 1px solid var(--border);
}

button {
    padding: 0.75rem 1.5rem;
    background-color: var(--accent);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 600;
    transition: background-color 0.2s, transform 0.1s;
}

button:hover {
    background-color: var(--accent-hover);
}

button:active {
    transform: translateY(1px);
}

.primary-btn {
    flex: 1;
}

.small-btn {
    padding: 0.4rem 0.8rem;
    font-size: 0.75rem;
    background-color: var(--bg-primary);
    color: var(--text-secondary);
}

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

footer {
    background-color: var(--bg-secondary);
    padding: 0.75rem 2rem;
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.8rem;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border);
}

/* Responsive */
@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto 1fr;
    }

    .output-panel {
        grid-column: 1;
        grid-row: 1;
        max-height: 30vh;
    }

    .stack-panel {
        grid-column: 1;
        grid-row: 2;
        max-height: 30vh;
    }

    .input-panel {
        grid-column: 1;
        grid-row: 3;
    }

    header h1 {
        font-size: 1.5rem;
    }
}