:root {
    --bg-color: #121212;
    --surface-color: #1e1e1e;
    --primary-color: #bb86fc;
    --text-main: #ffffff;
    --text-muted: #a0a0a0;
    --border-color: #333333;
}

* { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; }

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

/* Login Screen */
.login-container { display: flex; justify-content: center; align-items: center; height: 100vh; padding: 20px; }
.login-box { background: var(--surface-color); padding: 30px; border-radius: 12px; width: 100%; max-width: 400px; box-shadow: 0 4px 20px rgba(0,0,0,0.5); }
.login-box h2 { margin-bottom: 20px; text-align: center; }

/* Layout & Sidebar */
.app-layout { display: flex; flex: 1; overflow: hidden; }
.sidebar { width: 250px; background: var(--surface-color); padding: 20px 0; border-right: 1px solid var(--border-color); display: flex; flex-direction: column; }
.sidebar a { color: var(--text-main); text-decoration: none; padding: 15px 20px; display: block; border-bottom: 1px solid var(--border-color); }
.sidebar a:hover { background: #2c2c2c; color: var(--primary-color); }
.sidebar .logout { margin-top: auto; border-top: 1px solid var(--border-color); border-bottom: none; color: #ff5252; }

.main-content { flex: 1; padding: 20px; overflow-y: auto; }

/* Forms */
.form-group { margin-bottom: 15px; }
label { display: block; margin-bottom: 5px; color: var(--text-muted); font-size: 0.9em; }
input, select, textarea { width: 100%; padding: 12px; border-radius: 8px; border: 1px solid var(--border-color); background: var(--bg-color); color: var(--text-main); font-size: 1em; }
input[type="file"] { padding: 9px; }
button { width: 100%; padding: 14px; border: none; border-radius: 8px; background: var(--primary-color); color: #000; font-size: 1em; font-weight: bold; cursor: pointer; margin-top: 10px; }
button:hover { opacity: 0.9; }

/* Tables */
table { width: 100%; border-collapse: collapse; margin-top: 20px; }
th, td { padding: 12px; text-align: left; border-bottom: 1px solid var(--border-color); }
th { color: var(--text-muted); }

/* Mobile Responsiveness */
@media (max-width: 768px) {
    .app-layout { flex-direction: column; }
    .sidebar { width: 100%; height: auto; border-right: none; border-bottom: 1px solid var(--border-color); flex-direction: row; flex-wrap: wrap; justify-content: space-around; padding: 10px 0; }
    .sidebar a { border-bottom: none; padding: 10px; text-align: center; flex: 1; font-size: 0.9em; }
    .sidebar .logout { border-top: none; margin-top: 0; }
}