:root {
    --primary: #6366f1;
    --secondary: #ec4899;
    --dark: #0f172a;
    --light: #f8fafc;
    --success: #10b981;
    --warning: #f59e0b;
    --border: #e2e8f0;
    --gradient-1: #667eea;
    --gradient-2: #764ba2;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

body {
    background: linear-gradient(135deg, #f0f2f5 0%, #e2e8f0 100%);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    background: linear-gradient(135deg, var(--dark) 0%, #1e293b 50%, #334155 100%);
    color: white;
    padding: 25px 20px;
    text-align: center;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
    position: relative;
    z-index: 10;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(99,102,241,0.1) 0%, transparent 50%);
    animation: pulse-bg 10s ease-in-out infinite;
}

@keyframes pulse-bg {
    0%, 100% { transform: rotate(0deg); }
    50% { transform: rotate(180deg); }
}

header h1 {
    font-size: 2.8rem;
    margin-bottom: 8px;
    color: white;
    position: relative;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    background: linear-gradient(90deg, #fff, #c7d2fe, #fff);
    background-size: 200% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: shine 3s linear infinite;
}

@keyframes shine {
    to { background-position: 200% center; }
}

header p {
    font-size: 1.15rem;
    color: #94a3b8;
    position: relative;
    font-weight: 300;
}

.main-container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.controls-sidebar {
    width: 380px;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(10px);
    padding: 30px;
    border-right: 1px solid var(--border);
    box-shadow: 4px 0 20px rgba(0,0,0,0.05);
    display: flex;
    flex-direction: column;
    gap: 22px;
    z-index: 5;
    overflow-y: auto;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
    position: relative;
}

.form-group:focus-within label {
    color: var(--primary);
}

label {
    font-weight: 600;
    color: var(--dark);
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: color 0.3s;
}

input, select {
    padding: 14px 16px;
    border: 2px solid var(--border);
    border-radius: 12px;
    font-size: 1rem;
    transition: all 0.3s ease;
    background: white;
}

input:focus, select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(99,102,241,0.1);
    transform: translateY(-1px);
}

.api-key-container {
    display: flex;
    gap: 10px;
}

.api-key-container input {
    flex: 1;
    min-width: 0;
}

.btn-auth {
    background: linear-gradient(135deg, var(--dark), #334155);
    color: white;
    border: none;
    padding: 0 18px;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
    white-space: nowrap;
}

.btn-auth:hover {
    background: linear-gradient(135deg, #1e293b, #475569);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

button.generate-btn {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border: none;
    padding: 18px 25px;
    font-size: 1.15rem;
    font-weight: bold;
    border-radius: 14px;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 15px;
    position: relative;
    overflow: hidden;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

button.generate-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    transition: left 0.5s;
}

button.generate-btn:hover::before {
    left: 100%;
}

button.generate-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 35px rgba(99,102,241,0.4);
}

button.generate-btn:disabled {
    background: #94a3b8;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

button.generate-btn:disabled::before {
    display: none;
}

button.download-btn {
    background: linear-gradient(135deg, var(--success), #059669);
    color: white;
    border: none;
    padding: 18px 25px;
    font-size: 1.15rem;
    font-weight: bold;
    border-radius: 14px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: none;
    animation: fadeIn 0.5s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

button.download-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 35px rgba(16,185,129,0.4);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.content-area {
    flex: 1;
    position: relative;
    background: linear-gradient(135deg, #e2e8f0 0%, #cbd5e1 100%);
    display: flex;
    flex-direction: column;
}

#output-frame {
    width: 100%;
    height: 100%;
    border: none;
    background-color: white;
    box-shadow: inset 0 0 30px rgba(0,0,0,0.05);
}

.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255,255,255,0.98);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 20;
    display: none;
    backdrop-filter: blur(5px);
}

.spinner {
    width: 60px;
    height: 60px;
    border: 5px solid #f3f3f3;
    border-top: 5px solid var(--primary);
    border-right: 5px solid var(--secondary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 25px;
}

.loading-text {
    color: var(--dark);
    font-size: 1.3rem;
    font-weight: 600;
    text-align: center;
}

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

footer {
    background: linear-gradient(135deg, var(--dark), #1e293b);
    color: #94a3b8;
    text-align: center;
    padding: 18px;
    font-size: 0.9rem;
    z-index: 10;
}

.feature-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, rgba(99,102,241,0.1), rgba(236,72,153,0.1));
    color: var(--primary);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 10px;
    border: 1px solid rgba(99,102,241,0.2);
}

.welcome-banner {
    background: linear-gradient(135deg, rgba(99,102,241,0.1), rgba(236,72,153,0.1));
    border: 2px dashed var(--primary);
    border-radius: 15px;
    padding: 20px;
    text-align: center;
    margin-bottom: 10px;
}

.welcome-banner h3 {
    color: var(--dark);
    margin-bottom: 8px;
    font-size: 1.1rem;
}

.welcome-banner p {
    color: #64748b;
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .main-container { flex-direction: column; }
    .controls-sidebar { width: 100%; border-right: none; border-bottom: 1px solid var(--border); }
    header h1 { font-size: 2rem; }
}