:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --success: #10b981;
    --radius-md: 12px;
    --radius-lg: 16px;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    height: 100vh;
    overflow: hidden;
}

#app {
    height: 100%;
    width: 100%;
}

.screen {
    display: none;
    height: 100%;
    width: 100%;
}

.screen.active {
    display: flex;
    flex-direction: column;
    animation: fadeIn 0.3s ease;
}

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

/* Typography */
h1 { font-size: 1.8rem; font-weight: 700; margin-bottom: 0.5rem; color: var(--text-main); }
h2 { font-size: 1.25rem; font-weight: 600; color: var(--text-main); }
p { color: var(--text-muted); margin-bottom: 1.5rem; }
.text-sm { font-size: 0.875rem; }
.text-muted { color: var(--text-muted); }
.text-center { text-align: center; }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: inherit;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: white;
    color: var(--text-main);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--bg-color);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.mt-4 { margin-top: 1rem; }

/* Cards & Layouts */
#start-screen, #end-screen {
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #f0f4f8 0%, #e2e8f0 100%);
}

.card {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 480px;
}

.icon-container {
    width: 64px;
    height: 64px;
    border-radius: 16px;
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.success-icon {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success);
    margin: 0 auto 1.5rem auto;
}

/* Forms */
.input-group {
    margin-bottom: 1.5rem;
    text-align: left;
}

.input-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.input-group input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s;
}

.input-group input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

#start-form .btn {
    width: 100%;
}

/* Evaluation Screen Header */
.app-header {
    background: white;
    padding: 1rem 2rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.header-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.badge {
    background: var(--bg-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-muted);
    border: 1px solid var(--border-color);
}

.progress-text {
    font-weight: 500;
    font-size: 0.875rem;
}

.progress-bar-container {
    height: 6px;
    background: var(--bg-color);
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--primary);
    width: 0%;
    transition: width 0.3s ease;
}

/* Split View */
.split-view {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.pdf-panel {
    flex: 2;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    background: var(--bg-color);
}

.form-panel {
    flex: 1;
    min-width: 350px;
    max-width: 500px;
    display: flex;
    flex-direction: column;
    background: white;
    overflow-y: auto;
}

.panel-header {
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    background: white;
}

.pdf-container {
    flex: 1;
    padding: 1rem;
}

.pdf-container iframe {
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    background: white;
}

.eval-form {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    flex: 1;
}

/* Likert Scale Specific Styling */
.criterion-group {
    background: var(--bg-color);
    padding: 1.25rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.criterion-title {
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-main);
}

.likert-scale {
    display: flex;
    justify-content: space-between;
    gap: 0.5rem;
}

.likert-item {
    flex: 1;
    position: relative;
}

.likert-item input[type="radio"] {
    position: absolute;
    opacity: 0;
    cursor: pointer;
}

.likert-label {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem 0.25rem;
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
    font-size: 0.875rem;
    font-weight: 500;
}

.likert-item input[type="radio"]:checked + .likert-label {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px white, 0 0 0 4px var(--primary);
}

.likert-item input[type="radio"]:hover + .likert-label {
    border-color: var(--primary);
}

.likert-legend {
    display: flex;
    justify-content: space-between;
    margin-top: 0.5rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.form-actions {
    margin-top: auto;
    padding-top: 1.5rem;
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    border-top: 1px solid var(--border-color);
}