:root {
    --bg-color: #f4f7fb;
    --card-bg: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --primary-blue: #60a5fa;     /* Matte light blue */
    --primary-blue-hover: #3b82f6;
    --border-color: #e2e8f0;
    --danger-red: #ef4444;
    --success-green: #10b981;
    --warning-yellow: #f59e0b;
    
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --radius-md: 8px;
    --radius-lg: 12px;
}

* {
    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;
    padding: 2rem 1rem;
}

.container {
    max-width: 900px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    color: var(--primary-blue-hover);
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-muted);
    font-size: 1.1rem;
}

.card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: 1.5rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
}

.add-form h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

#student-form {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: flex-end;
}

.form-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 200px;
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

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

.form-group input:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(96, 165, 250, 0.2);
}

.btn {
    padding: 0.75rem 1.5rem;
    background-color: var(--primary-blue);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
    height: 45px;
}

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

.btn-small {
    padding: 0.4rem 0.8rem;
    font-size: 0.875rem;
    background-color: #f1f5f9;
    color: var(--text-main);
    border: 1px solid var(--border-color);
}

.btn-small:hover {
    background-color: #e2e8f0;
}

.btn-danger {
    color: var(--danger-red);
    background-color: transparent;
    border: 1px solid var(--border-color);
}
.btn-danger:hover {
    background-color: #fef2f2;
}


/* Leaderboard section */
.leaderboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.leaderboard-header h2 {
    font-size: 1.5rem;
}

.sort-options {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.sort-options select {
    padding: 0.4rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    font-family: inherit;
    outline: none;
}

/* Student Cards */
.student-card {
    background: var(--card-bg);
    border-radius: var(--radius-md);
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.sc-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
}

.sc-name {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-main);
}

.sc-prop-date {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

/* Timeline Layout */
.timeline {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-top: 1rem;
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 10px;
    left: 10%;
    right: 10%;
    height: 4px;
    background-color: var(--border-color);
    z-index: 0;
    border-radius: 2px;
}

.milestone {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    flex: 1;
}

.ms-dot {
    width: 24px;
    height: 24px;
    background-color: var(--card-bg);
    border: 4px solid var(--border-color);
    border-radius: 50%;
    margin-bottom: 0.5rem;
    transition: all 0.3s;
}

.milestone.completed .ms-dot {
    background-color: var(--primary-blue);
    border-color: var(--primary-blue);
}

.milestone.current .ms-dot {
    border-color: var(--primary-blue);
    background-color: var(--card-bg);
    box-shadow: 0 0 0 4px rgba(96, 165, 250, 0.2);
}

.milestone.overdue .ms-dot {
    border-color: var(--danger-red);
    background-color: var(--card-bg);
    box-shadow: 0 0 0 4px rgba(239, 68, 68, 0.2);
}

.ms-label {
    font-weight: 600;
    font-size: 0.875rem;
    margin-bottom: 0.25rem;
}

.ms-date {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.ms-status {
    font-size: 0.75rem;
    margin-top: 0.25rem;
    font-weight: 500;
    padding: 2px 6px;
    border-radius: 10px;
}

/* Status Colors */
.status-ontrack {
    color: var(--success-green);
    background: #d1fae5;
}
.status-upcoming {
    color: var(--primary-blue-hover);
    background: #dbeafe;
}
.status-overdue {
    color: var(--danger-red);
    background: #fee2e2;
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-muted);
    background: var(--card-bg);
    border-radius: var(--radius-md);
    border: 1px dashed var(--border-color);
}