:root {
    --bg-color: #0f172a;
    --panel-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --success-color: #4ade80;
    --fail-color: #f87171;
    --border-color: #334155;
    --font-family: 'Inter', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    height: 100vh;
    display: flex;
    flex-direction: column;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100%;
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    padding: 1rem;
}

.app-header {
    text-align: center;
    margin-bottom: 1.5rem;
}

.app-header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, var(--accent-color), #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.app-header p {
    color: var(--text-secondary);
}

.main-content {
    display: flex;
    gap: 1.5rem;
    flex: 1;
    min-height: 0;
    /* Important for scroll */
}

.canvas-container {
    flex: 1;
    background-color: var(--panel-bg);
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

canvas {
    flex: 1;
    width: 100%;
    height: 100%;
    cursor: crosshair;
    touch-action: none;
}

.canvas-controls {
    position: absolute;
    bottom: 1rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 1rem;
    background: rgba(15, 23, 42, 0.8);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    backdrop-filter: blur(4px);
    border: 1px solid var(--border-color);
}

.btn {
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    border: none;
    font-weight: 600;
    cursor: pointer;
    font-family: inherit;
    transition: all 0.2s;
}

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

.btn.primary:hover {
    filter: brightness(1.1);
}

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

.btn.secondary:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.sidebar {
    width: 350px;
    display: flex;
    flex-direction: column;
}

.panel {
    background-color: var(--panel-bg);
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    height: 100%;
    overflow-y: auto;
}

.panel h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.proof-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.proof-item {
    background-color: rgba(255, 255, 255, 0.03);
    border-radius: 0.75rem;
    padding: 1rem;
    display: flex;
    gap: 1rem;
    transition: background-color 0.3s;
    border: 1px solid transparent;
}

.proof-item.success {
    background-color: rgba(74, 222, 128, 0.1);
    border-color: rgba(74, 222, 128, 0.3);
}

.status-icon {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 2px solid var(--text-secondary);
    flex-shrink: 0;
    margin-top: 0.25rem;
    position: relative;
    transition: all 0.3s;
}

.proof-item.success .status-icon {
    border-color: var(--success-color);
    background-color: var(--success-color);
}

.proof-item.success .status-icon::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: var(--panel-bg);
    font-size: 0.875rem;
    font-weight: bold;
}

.proof-content h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.proof-content p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.stats {
    font-family: 'Courier New', monospace;
    font-size: 0.75rem;
    color: var(--accent-color);
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.success-message {
    margin-top: 2rem;
    text-align: center;
    padding: 1rem;
    background: linear-gradient(135deg, var(--success-color), #22c55e);
    color: var(--bg-color);
    border-radius: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
    animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.hidden {
    display: none;
    opacity: 0;
}

@keyframes popIn {
    0% {
        transform: scale(0.8);
        opacity: 0;
    }

    100% {
        transform: scale(1);
        opacity: 1;
    }
}

@media (max-width: 900px) {
    .main-content {
        flex-direction: column;
        overflow: hidden;
        /* Prevent body scroll if we want app-feel */
    }

    .canvas-container {
        flex: 0 0 50vh;
        /* Fixed height, half screen */
        height: 50vh;
        border-radius: 1rem 1rem 0 0;
    }

    .sidebar {
        width: 100%;
        flex: 1;
        /* Take remaining space */
        min-height: 0;
        /* Allow shrinking */
        height: auto;
    }

    .panel {
        border-radius: 0 0 1rem 1rem;
        border-top: none;
    }
}