:root {
    --primary-color: #007bff;
    --success-color: #28a745;
    --error-color: #dc3545;
    --light-grey: #f8f9fa;
    --dark-grey: #343a40;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

nav {
    width: 100%;
    max-width: 500px;
    margin-bottom: 1rem;
    text-align: left;
    padding: 0 1rem;
    box-sizing: border-box;
}

/* --- CHANGE 2: REMOVE UNDERLINE --- */
nav a {
    text-decoration: none; /* This removes the line */
    color: #6c757d;       /* A nice grey color */
    font-weight: 500;
    transition: color 0.2s ease;
}

/* Add a hover effect so people know it's clickable */
nav a:hover {
    color: var(--primary-color);
}

body {
    font-family: var(--font-family);
    background-color: var(--light-grey);
    color: var(--dark-grey);
    display: flex;
    flex-direction: column;
    /* justify-content: center; */
    justify-content: flex-start;
    padding-top: 80px;

    align-items: center;
    min-height: 100vh;
    margin: 0;
    /* padding: 20px; */
    box-sizing: border-box;
}

main {
    background-color: #ffffff;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    padding: 2rem 3rem;
    width: 100%;
    max-width: 500px;
    text-align: center;
}

h2 {
    margin-top: 0;
    color: var(--dark-grey);
}

/* This hides the ugly default file input */
#file-input {
    display: none;
}

/* This is the new, styled button */
.file-label {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 12px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-weight: 500;
    transition: background-color 0.2s ease;
    margin-bottom: 1rem;
}

.file-label:hover {
    background-color: #0056b3;
}

#file-name {
    display: block;
    margin-bottom: 1.5rem;
    color: #6c757d;
    font-style: italic;
}

#upload-button {
    background-color: var(--success-color);
    color: white;
    font-size: 1rem;
    font-weight: 600;
    padding: 12px 30px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    width: 100%;
    transition: background-color 0.2s ease;
}

#upload-button:hover {
    background-color: #218838;
}

#status {
    font-size: 0.9rem;
    margin-top: 1.5rem;
    font-weight: 500;
}

.status-success {
    color: var(--success-color);
}

.status-error {
    color: var(--error-color);
}

.status-info {
    color: var(--dark-grey);
}

@keyframes shake {
    0% { transform: translateX(0); }
    25% { transform: translateX(-5px) rotate(-5deg); }
    50% { transform: translateX(5px) rotate(5deg); }
    75% { transform: translateX(-5px) rotate(-5deg); }
    100% { transform: translateX(0); }
}

/* Create a class to apply the animation */
.shake-animation {
    animation: shake 1s ease-in-out;
    animation-iteration-count: 2; /* Run only once */
}