:root {
    /* Palette */
    --primary: #4f8cff;
    --primary-hover: #3a7aff;
    --secondary: #70c1b3;
    --bg: #fafbff;
    --bg-glass: linear-gradient(135deg, rgba(255, 169, 135, 0.1), rgba(112, 193, 179, 0.1));
    --text-main: #232323;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border: #e2e8f0;
    --border-dark: #444850;
    --shadow-light: rgba(71, 85, 105, 0.1);

    /* Typography */
    --font-family: "Inter", system-ui, Arial, sans-serif;
    --font-size-base: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.75rem;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-bold: 700;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 3rem;
    --space-15: 5rem;

    /* Border radius */
    --radius-base: 0.5rem;
    --radius-lg: 1rem;

    /* Transition */
    --transition: 0.2s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #23272f;
        --text-main: #fafbff;
        --border: #444850;
        --bg-glass: linear-gradient(135deg, rgba(79, 140, 255, 0.05), rgba(112, 193, 179, 0.06));
    }
}

/* Reset and base styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background: var(--bg);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    color: var(--text-main);
    min-height: 100vh;
    display: block;
    justify-content: center;
    padding: var(--space-8);
    text-align: center;
}

h1 {
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--space-6);
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}


div {
    display: flex;
    justify-content: center;
}

form {
    background: var(--bg-glass);
    box-shadow: 0 6px 24px var(--shadow-light);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--space-8);
    max-width: 420px;
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}

label {
    font-weight: var(--font-weight-medium);
    margin-bottom: var(--space-1);
    color: var(--text-secondary);
}

#file-label,
select {
    padding: var(--space-10) var(--space-3);
    font-size: var(--font-size-base);
    border: 1px solid var(--border);
    border-radius: var(--radius-base);
    background: rgba(255,255,255,0.10); /* translucent glass effect */
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    color: var(--text-main);
    transition: border var(--transition), box-shadow var(--transition);
    margin-bottom: var(--space-2);
}

#file-label:focus,
select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px var(--primary)30;
}

/* Dropdown option styling (works in most browsers except Safari/Firefox) */
select option {
    background: #23272f;
    color: #fafbff;
    text-align: center;
}

button[type="submit"] {
    background: var(--primary);
    color: #fff;
    font-weight: var(--font-weight-medium);
    padding: var(--space-2) var(--space-4);
    border: none;
    border-radius: var(--radius-base);
    font-size: var(--font-size-base);
    cursor: pointer;
    box-shadow: 0 2px 6px var(--shadow-light);
    transition: background var(--transition), transform var(--transition);

}

button[type="submit"]:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: translateY(-2px) scale(1.03);
}

button[type="submit"]:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

#message {
    margin-top: var(--space-4);
    min-height: 2em;
    font-size: var(--font-size-base);
    color: var(--secondary);
}

#feature-msg {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    text-align: center;
    margin-bottom: var(--space-6);
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Responsive */
@media (max-width: 600px) {
    body {
        padding: var(--space-2);
    }
    form {
        padding: var(--space-4);
    }
    #feature-msg {
        font-size: var(--font-size-lg);
    }
}