:root {
    --bg-dark: #0f172a;
    --bg-surface: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-primary: #3b82f6;
    --accent-hover: #2563eb;
    --border-color: #334155;
    --top-bar-height: 60px;
    --danger: #ef4444;
    --success: #10b981;
}

* {
    box-sizing: border-box;
}

body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-primary);
    overflow: hidden;
}

#wrapper {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

#top-bar {
    height: var(--top-bar-height);
    background-color: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    z-index: 100;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 1.2rem;
}

.brand {
    color: var(--text-primary);
}

.tag {
    color: var(--accent-primary);
}

#problem-info {
    display: flex;
    align-items: center;
    gap: 40px;
}

#problem-nav {
    display: flex;
    align-items: center;
    gap: 12px;
}

#problem-indicator {
    font-size: 0.9rem;
    color: var(--text-secondary);
    min-width: 80px;
    text-align: center;
}

.nav-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
}

.nav-btn:hover:not(:disabled) {
    background-color: var(--bg-dark);
    border-color: var(--accent-primary);
}

.nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

#countdown-timer {
    display: flex;
    align-items: center;
    gap: 8px;
}

#timer-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

#timer-display {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.2rem;
    color: var(--accent-primary);
    font-weight: 600;
}

.primary-btn {
    background-color: var(--accent-primary);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

#content {
    flex-grow: 1;
    position: relative;
}

#ide-frame {
    width: 100%;
    height: 100%;
    border: none;
}

#toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 12px 24px;
    border-radius: 8px;
    background-color: var(--bg-surface);
    border: 1px solid var(--accent-primary);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    transition: opacity 0.3s, transform 0.3s;
    z-index: 1000;
}

#toast.hidden {
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;
}

#toast.success {
    border-color: var(--success);
    color: var(--success);
}

#toast.error {
    border-color: var(--danger);
    color: var(--danger);
}