:root {
    --bg: #1e1e2e;
    --bg-panel: #181825;
    --bg-terminal: #11111b;
    --text: #cdd6f4;
    --text-muted: #6c7086;
    --accent: #89b4fa;
    --accent-green: #a6e3a1;
    --accent-red: #f38ba8;
    --accent-yellow: #f9e2af;
    --border: #313244;
}

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

body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: var(--bg);
    color: var(--text);
    height: 100vh;
    overflow: hidden;
}

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

header {
    background: var(--bg-panel);
    padding: 12px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border);
}

header h1 {
    font-size: 18px;
    font-weight: 600;
    color: var(--accent);
}

#status-bar {
    display: flex;
    gap: 10px;
    align-items: center;
}

#session-status {
    font-size: 13px;
    padding: 4px 10px;
    border-radius: 6px;
}

.status-connected { background: rgba(166,227,161,0.15); color: var(--accent-green); }
.status-disconnected { background: rgba(243,139,168,0.15); color: var(--accent-red); }

button {
    padding: 6px 14px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-panel);
    color: var(--text);
    cursor: pointer;
    font-size: 13px;
    transition: all 0.15s;
}

button:hover { border-color: var(--accent); }
button:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: var(--bg); border-color: var(--accent); font-weight: 600; }
.btn-primary:hover { opacity: 0.9; }

main {
    display: flex;
    flex: 1;
    overflow: hidden;
}

#sidebar {
    width: 300px;
    background: var(--bg-panel);
    border-right: 1px solid var(--border);
    padding: 16px;
    overflow-y: auto;
    flex-shrink: 0;
}

#sidebar h2 {
    font-size: 15px;
    margin-bottom: 12px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

#exercise-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 20px;
}

.exercise-item {
    padding: 10px 12px;
    border-radius: 6px;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all 0.15s;
}

.exercise-item:hover { background: rgba(137,180,250,0.1); }
.exercise-item.active { border-color: var(--accent); background: rgba(137,180,250,0.1); }

.exercise-item .ex-diff {
    font-size: 11px;
    color: var(--text-muted);
    margin-top: 2px;
}

.diff-facil { color: var(--accent-green); }
.diff-medio { color: var(--accent-yellow); }
.diff-dificil { color: var(--accent-red); }

#exercise-detail h3 { font-size: 15px; margin-bottom: 8px; }
#exercise-detail p { font-size: 13px; color: var(--text-muted); margin-bottom: 10px; line-height: 1.5; }
#exercise-detail button { margin: 4px 4px 4px 0; }

#ex-hints {
    margin: 10px 0;
    padding: 10px;
    background: var(--bg-terminal);
    border-radius: 6px;
    font-family: monospace;
    font-size: 12px;
}

#ex-hints .hint { color: var(--accent-yellow); margin: 2px 0; }

#verify-results {
    margin-top: 12px;
}

.check-item {
    padding: 6px 10px;
    margin: 4px 0;
    border-radius: 4px;
    font-size: 13px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.check-passed { background: rgba(166,227,161,0.1); color: var(--accent-green); }
.check-failed { background: rgba(243,139,168,0.1); color: var(--accent-red); }

#terminal-area {
    flex: 1;
    padding: 12px;
    background: var(--bg-terminal);
    overflow: hidden;
}

#terminal {
    height: 100%;
    border-radius: 8px;
    overflow: hidden;
}

.muted { color: var(--text-muted); font-size: 13px; }