:root {
    /* Warm modern color palette */
    --bg-primary: #fef7f0;          /* Warm cream background */
    --bg-secondary: #fff8f0;        /* Lighter cream */
    --bg-card: #ffffff;             /* Pure white for cards */
    --surface-elevated: #fdfbf9;    /* Subtle warm white */
    --text-primary: #1a1a1a;        /* Rich black */
    --text-secondary: #6b7280;      /* Warm gray */
    --text-muted: #9ca3af;          /* Light gray */
    
    --accent-primary: #f59e0b;      /* Warm amber */
    --accent-secondary: #ea580c;    /* Orange */
    --accent-success: #10b981;      /* Emerald green */
    --accent-info: #3b82f6;         /* Blue */
    --accent-warning: #f59e0b;      /* Amber */
    --accent-danger: #ef4444;       /* Red */
    
    --border-light: #f3f4f6;        /* Very light border */
    --border-medium: #e5e7eb;       /* Medium border */
    --border-focus: #f59e0b;         /* Focused border */
    
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 25px rgba(0,0,0,0.12);
    --shadow-warm: 0 4px 20px rgba(245,158,11,0.15);
    
    --gradient-warm: linear-gradient(135deg, #fef7f0 0%, #fff8f0 100%);
    --gradient-accent: linear-gradient(135deg, #f59e0b 0%, #ea580c 100%);
    --gradient-card: linear-gradient(145deg, #ffffff 0%, #fdfbf9 100%);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--gradient-warm);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  font-weight: 400;
}

/* Glass morphism navbar */
.navbar-custom {
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(245, 158, 11, 0.1);
    box-shadow: 0 2px 20px rgba(0,0,0,0.06);
    transition: all 0.3s ease;
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 0 1rem;
}

/* Left side navigation group */
.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0.75rem 1rem;
}

.navbar-left {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.navbar-brand {
    color: var(--text-primary) !important;
    font-weight: 600;
    font-size: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: all 0.3s ease;
    margin-right: 0;
}

.navbar-brand:hover {
    transform: translateY(-1px);
}

.navbar-brand i {
    color: var(--accent-primary);
    font-size: 1.5rem;
    filter: drop-shadow(0 2px 4px rgba(245,158,11,0.3));
}

/* Navigation links styling */
.nav-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
}

.nav-link {
    color: var(--text-secondary) !important;
    font-weight: 500;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 12px;
    transition: all 0.3s ease;
    position: relative;
}

.nav-link:hover {
    color: var(--accent-primary) !important;
    background: rgba(245, 158, 11, 0.08);
    transform: translateY(-1px);
}

.about-link {
    display: flex;
    align-items: center;
}

.logo {
    height: 48px;
    width: auto;
    transition: all 0.3s ease;
}

.logo:hover {
    transform: scale(1.05);
}

/* Main container styling */
.main-container {
    margin-top: 100px;
    padding: 2rem 1rem;
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

/* Upload section styling */
.upload-section {
    background: var(--gradient-card);
    border: 1px solid var(--border-light);
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    transition: all 0.4s ease;
    position: relative;
    padding: 2.5rem;
    margin-bottom: 2rem;
}

.upload-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-accent);
}

.upload-section:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-warm);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    text-align: center;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* File drop area with modern styling */
.upload-area {
    border: 3px dashed var(--border-medium);
    border-radius: 20px;
    padding: 3rem 2rem;
    text-align: center;
    background: var(--bg-secondary);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    min-height: 280px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.upload-area::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(245,158,11,0.1), transparent);
    transition: left 0.6s;
}

.upload-area:hover {
    border-color: var(--accent-primary);
    background: rgba(245, 158, 11, 0.03);
    transform: scale(1.02);
    box-shadow: var(--shadow-warm);
}

.upload-area:hover::before {
    left: 100%;
}

.upload-area.dragover {
    border-color: var(--accent-primary);
    background: rgba(245, 158, 11, 0.08);
    box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.1);
    animation: pulse 1.5s infinite;
}

@keyframes pulse {
    0% { box-shadow: 0 0 0 0 rgba(245, 158, 11, 0.4); }
    70% { box-shadow: 0 0 0 10px rgba(245, 158, 11, 0); }
    100% { box-shadow: 0 0 0 0 rgba(245, 158, 11, 0); }
}

.upload-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
    opacity: 0.8;
    color: var(--accent-primary);
    filter: drop-shadow(0 4px 8px rgba(245,158,11,0.2));
    transition: all 0.3s ease;
}

.upload-area:hover .upload-icon {
    transform: scale(1.1) rotate(5deg);
}

.upload-text {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.browse-link {
    color: var(--accent-primary);
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
}

.browse-link:hover {
    color: var(--accent-secondary);
    text-decoration: underline;
}

.upload-info {
    font-size: 0.9rem;
    color: var(--text-muted);
    max-width: 500px;
    margin-top: 0.5rem;
}

.file-input {
    display: none;
}

.uploaded-files {
    margin-top: 1.5rem;
}

/* File item styling */
.file-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.25rem;
    background: var(--bg-card);
    border: 2px solid var(--border-light);
    border-radius: 16px;
    margin-bottom: 0.75rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.file-item:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
    transform: translateX(8px);
}

.file-info {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex: 1;
}

.file-icon {
    width: 28px;
    height: 28px;
    opacity: 0.8;
    color: var(--accent-primary);
    flex-shrink: 0;
}

.file-details {
    display: flex;
    flex-direction: column;
    text-align: left;
}

.file-name {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.file-size {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Remove file button styling */
.remove-file {
    background: linear-gradient(135deg, var(--accent-danger) 0%, #dc2626 100%);
    color: white;
    border: none;
    border-radius: 12px;
    padding: 0.5rem 0.75rem;
    font-weight: 600;
    transition: all 0.3s ease;
    cursor: pointer;
    flex-shrink: 0;
}

.remove-file:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(239,68,68,0.3);
}

/* Process section */
.process-section {
    text-align: center;
    margin-top: 2.5rem;
}

/* Modern button styling */
.process-btn {
    border-radius: 16px;
    padding: 0.875rem 2.5rem;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border: none;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    background: var(--gradient-accent);
    color: white;
    cursor: pointer;
    min-width: 220px;
}

.process-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.6s;
}

.process-btn:hover:not(:disabled)::before {
    left: 100%;
}

.process-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-warm);
}

.process-btn:disabled {
    background: linear-gradient(135deg, var(--text-muted) 0%, #a0aec0 100%);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.process-btn:active:not(:disabled) {
    transform: translateY(0) scale(0.98);
}

/* Status message styling */
.status-message {
    margin-top: 1rem;
    padding: 1.25rem;
    border-radius: 16px;
    font-weight: 500;
    display: none;
    background: var(--bg-card);
    border-left: 4px solid var(--accent-info);
    box-shadow: var(--shadow-sm);
}

.status-message.success {
    background: var(--bg-card);
    color: var(--accent-success);
    border-left-color: var(--accent-success);
}

.status-message.error {
    background: var(--bg-card);
    color: var(--accent-danger);
    border-left-color: var(--accent-danger);
}

.status-message.info {
    background: var(--bg-card);
    color: var(--accent-info);
    border-left-color: var(--accent-info);
}

/* Loading animation */
@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-radius: 50%;
    border-top-color: var(--accent-primary);
    animation: spin 1s ease-in-out infinite;
    margin-right: 8px;
}

/* Responsive design */
@media (max-width: 768px) {
    .main-container {
        margin-top: 80px;
        padding: 1.5rem 1rem;
    }

    .navbar-left {
        gap: 1rem;
    }
    
    .nav-links {
        gap: 0.5rem;
    }
    
    .nav-link {
        font-size: 0.9rem;
        padding: 0.4rem 0.8rem;
    }

    .upload-section {
        padding: 1.5rem;
    }

    .upload-area {
        padding: 2rem 1rem;
        min-height: 250px;
    }

    .section-title {
        font-size: 1.25rem;
    }

    .upload-text {
        font-size: 1rem;
    }

    .process-btn {
        width: 100%;
    }

    .logo {
        height: 40px;
    }
}

@media (max-width: 576px) {
    .nav-links {
        flex-direction: column;
        gap: 0.25rem;
    }

    .file-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .file-info {
        width: 100%;
        margin-bottom: 0.75rem;
    }

    .remove-file {
        width: 100%;
    }
}