:root {
    --primary-bg: #e0eafc;
    --secondary-bg: #cfdef3;
    --card-bg: #ffffff;
    --text-main: #2d3748;
    --text-muted: #718096;
    --accent-blue: #4299e1;
    --accent-purple: #9f7aea;
    --error-red: #f56565;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    --shadow-soft: 0 10px 25px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background: linear-gradient(135deg, var(--primary-bg) 0%, var(--secondary-bg) 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-main);
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 500px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 8px;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

header p {
    color: var(--text-muted);
    font-weight: 500;
}

.card {
    background: var(--card-bg);
    border-radius: 24px;
    padding: 30px;
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-hover);
}

/* Tabs */
.tabs {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    background: #f7fafc;
    padding: 6px;
    border-radius: 16px;
    margin-bottom: 24px;
}

.tab-btn {
    background: transparent;
    border: none;
    padding: 10px 5px;
    border-radius: 12px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
}

.tab-btn i {
    font-size: 1.1rem;
}

.tab-btn:hover {
    color: var(--accent-blue);
}

.tab-btn.active {
    background: #ffffff;
    color: var(--accent-purple);
    box-shadow: 0 4px 6px rgba(0,0,0,0.02);
}

/* Input Area */
.input-group {
    position: relative;
    margin-bottom: 24px;
}

#qr-input {
    width: 100%;
    padding: 16px 20px;
    border: 2px solid #edf2f7;
    border-radius: 16px;
    font-size: 1rem;
    color: var(--text-main);
    transition: var(--transition);
    background: #f7fafc;
    outline: none;
}

#qr-input:focus {
    border-color: var(--accent-blue);
    background: #ffffff;
    box-shadow: 0 0 0 4px rgba(66, 153, 225, 0.15);
}

.error-msg {
    color: var(--error-red);
    font-size: 0.85rem;
    margin-top: 8px;
    padding-left: 10px;
    display: none;
    animation: fadeIn 0.3s ease;
}

.error-msg.show {
    display: block;
}

/* Generate Button */
.primary-btn {
    width: 100%;
    padding: 16px;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    color: white;
    border: none;
    border-radius: 16px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    transition: var(--transition);
    box-shadow: 0 10px 20px rgba(159, 122, 234, 0.3);
}

.primary-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 25px rgba(159, 122, 234, 0.4);
}

.primary-btn:active {
    transform: translateY(0);
}

/* QR Result Area */
.qr-result {
    margin-top: 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    border-top: 1px solid #edf2f7;
    padding-top: 30px;
    transition: var(--transition);
}

.qr-result.hidden {
    display: none;
}

.qr-wrapper {
    position: relative;
    width: 200px;
    height: 200px;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 16px;
    padding: 10px;
    background: #ffffff;
    box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    margin-bottom: 24px;
    animation: scaleIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

#qr-image {
    width: 100%;
    height: 100%;
    object-fit: contain;
    border-radius: 8px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

#qr-image.loaded {
    opacity: 1;
}

.action-buttons {
    display: flex;
    gap: 12px;
    width: 100%;
}

.secondary-btn {
    flex: 1;
    padding: 12px;
    background: white;
    border: 2px solid #edf2f7;
    color: var(--text-main);
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
}

.secondary-btn:hover {
    border-color: var(--accent-blue);
    color: var(--accent-blue);
    background: #f7fafc;
}

/* Loader */
.qr-loader {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background: rgba(255,255,255,0.8);
    border-radius: 16px;
    z-index: 10;
}

.qr-loader.hidden {
    display: none;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--accent-purple);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-5px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes scaleIn {
    from { opacity: 0; transform: scale(0.9); }
    to { opacity: 1; transform: scale(1); }
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Mobile Responsiveness */
@media (max-width: 480px) {
    .tabs {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    .action-buttons {
        flex-direction: column;
    }
    .card {
        padding: 24px;
    }
}