/* =========================================================
   GLOBAL DESIGN SYSTEM & THEME
   ========================================================= */
:root {
    --primary-color: #ecf077;       /* Deep professional slate/navy */
    --accent-blue: #25de72;         /* Modern tech blue */
    --accent-blue-hover: #134ef0;   /* Darker blue on hover */
    --success-green: #4ff08a;       /* Clean success indicator */
    --danger-red: #dc2626;          /* Error red */
    
    --card-bg: transparent;         /* CHANGED: Made the white box transparent */
    --text-main: #46f760;           /* Deep neutral gray for text */
    --text-muted: #64748b;          /* Lighter gray for subtitles */
    --border-color: #554af7;        /* Subtle border tone for inputs */
    
    --radius: 12px;                 /* Smooth modern rounded corners */
    --shadow: none;                 /* CHANGED: Removed the floating shadow */
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    /* Explicitly setting the uploaded image as the background behind everything */
    background-image: url('/background.png');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
    color: var(--text-main);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
}

/* =========================================================
   SHARED CONTAINERS & CARDS (SaaS Grade)
   ========================================================= */
.upload-container, .container, .form-card, .login-container {
    background: var(--card-bg);
    padding: 40px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border: none;                   /* CHANGED: Removed border so it blends perfectly */
    width: 100%;
    max-width: 520px;
    box-sizing: border-box;
}

.container {
    max-width: 1200px; /* Wider for Teacher Command Center */
}

h1, h2 {
    color: var(--primary-color);
    font-weight: 700;
    margin-top: 0;
    text-align: center;
    letter-spacing: -0.025em;
}

p.subtitle {
    text-align: center;
    color: var(--text-muted);
    margin-bottom: 30px;
    font-size: 14px;
}

/* =========================================================
   COMPANY BRANDING HEADER (Logo & Name)
   ========================================================= */
.brand-header {
    text-align: center;
    margin-bottom: 25px;
}

.brand-logo {
    max-width: 80px;       /* Controlled responsive width */
    height: auto;          /* Preserves natural aspect ratio */
    object-fit: contain;
    border-radius: 8px;
    margin-bottom: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

.brand-title {
    font-size: 20px;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: -0.02em;
    margin: 0;
}

.brand-tagline {
    font-size: 13px;
    color: var(--text-muted);
    margin-top: 4px;
}

/* =========================================================
   FORM CONTROLS & INPUTS
   ========================================================= */
.form-group {
    margin-bottom: 22px;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--primary-color);
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

input[type="text"], 
input[type="email"], 
input[type="password"], 
input[type="number"], 
input[type="file"], 
select, 
textarea {
    width: 100%;
    padding: 12px 14px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: #f8fafc;
    color: var(--text-main);
    font-size: 14px;
    box-sizing: border-box;
    transition: all 0.2s ease;
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--accent-blue);
    background-color: #ffffff;
    box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

/* =========================================================
   BUTTONS
   ========================================================= */
button {
    width: 100%;
    padding: 12px 20px;
    background-color: var(--accent-blue);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
    box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.2);
}

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

button:active {
    transform: scale(0.99);
}

/* =========================================================
   TABLES (Teacher Dashboard)
   ========================================================= */
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
    background: white;
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

th, td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
    font-size: 14px;
}

th {
    background-color: var(--primary-color);
    color: white;
    font-weight: 600;
}

tr:hover {
    background-color: #f8fafc;
}

/* =========================================================
   UTILITIES & FEEDBACK BOXES
   ========================================================= */
.badge {
    background: #fef3c7;
    color: #92400e;
    padding: 6px 10px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 700;
}

.logout-link