:root {
    --primary: #4F46E5;
    --primary-hover: #4338CA;
    --primary-rgb: 79, 70, 229;
    --secondary: #10B981;
    --bg: #F3F4F6;
    --surface: #FFFFFF;
    --input-bg: #FFFFFF;
    --text: #1F2937;
    --text-light: #6B7280;
    --border: #E5E7EB;
}

body.dark-mode {
    --primary: #818CF8;
    --primary-hover: #6366F1;
    --primary-rgb: 129, 140, 248;
    --bg: #0F172A;
    --surface: #1E293B;
    --input-bg: #334155;
    --text: #F8FAFC;
    --text-light: #94A3B8;
    --border: #334155;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Inter', sans-serif; background-color: var(--bg); color: var(--text); transition: background-color 0.3s, color 0.3s; }
a { text-decoration: none; color: var(--primary); }
a:hover { text-decoration: underline; }

.app-container { display: flex; min-height: 100vh; }
.sidebar { width: 250px; background: var(--surface); border-right: 1px solid var(--border); padding: 1.5rem; display: flex; flex-direction: column; gap: 1rem; }
.sidebar h2 { font-size: 1.2rem; margin-bottom: 2rem; color: var(--primary); }
.nav-link { padding: 0.75rem 1rem; border-radius: 0.5rem; text-decoration: none !important; color: var(--text); font-weight: 500; transition: background 0.2s; display: flex; justify-content: space-between; align-items: center; }
.nav-link:hover, .nav-link.active { background: rgba(var(--primary-rgb), 0.1); color: var(--primary); }
.nav-link .badge { background: #EF4444; color: white; padding: 2px 6px; border-radius: 12px; font-size: 0.75rem; }

.main-content { flex: 1; padding: 2rem; overflow-y: auto; }
.header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 2rem; }
.card { background: var(--surface); padding: 1.5rem; border-radius: 1rem; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1); margin-bottom: 1.5rem; }

.btn { display: inline-flex; align-items: center; gap: 0.5rem; justify-content:center; padding: 0.5rem 1rem; background: var(--primary); color: white !important; border-radius: 0.5rem; border: none; cursor: pointer; text-decoration: none !important; font-weight: 500; transition: opacity 0.2s; }
.btn:hover { opacity: 0.9; }
.btn-sm { padding: 0.25rem 0.5rem; font-size: 0.875rem; }
.btn-secondary { background: var(--text-light); }
.btn-danger { background: #EF4444; }

.form-group { margin-bottom: 1rem; }
.form-group label { display: block; margin-bottom: 0.5rem; font-weight: 500; }
.form-control { width: 100%; padding: 0.75rem; border: 1px solid var(--border); border-radius: 0.5rem; font-family: inherit; background: var(--input-bg); color: var(--text); }

table { width: 100%; border-collapse: collapse; margin-top: 1rem; }
th, td { padding: 0.75rem; text-align: left; border-bottom: 1px solid var(--border); }
th { color: var(--text-light); font-weight: 500; }

.kanban-board { display: flex; gap: 1.5rem; overflow-x: auto; padding-bottom: 1rem; }
.kanban-col { background: rgba(0,0,0,0.03); border-radius: 1rem; width: 320px; min-width: 320px; display: flex; flex-direction: column; }
body.dark-mode .kanban-col { background: rgba(255,255,255,0.03); }
.kanban-col-header { padding: 1rem; font-weight: 600; border-bottom: 2px solid var(--border); }
.kanban-tasks { padding: 1rem; flex: 1; min-height: 200px; display: flex; flex-direction: column; gap: 1rem; }
.kanban-task { background: var(--surface); padding: 1rem; border-radius: 0.5rem; box-shadow: 0 2px 4px rgba(0,0,0,0.05); border: 1px solid var(--border); cursor: grab; }
.kanban-task:active { cursor: grabbing; }

.modal-overlay { position: fixed; top: 0; left: 0; right: 0; bottom: 0; background: rgba(0,0,0,0.5); display: flex; align-items: center; justify-content: center; z-index: 1000; opacity: 0; pointer-events: none; transition: opacity 0.2s; }
.modal-overlay.active { opacity: 1; pointer-events: auto; }
.modal-content { background: var(--surface); padding: 2rem; border-radius: 1rem; width: 100%; max-width: 400px; transform: translateY(-20px); transition: transform 0.2s; }
.modal-overlay.active .modal-content { transform: translateY(0); }

#toast { position: fixed; bottom: 20px; right: 20px; background: var(--text); color: var(--surface); padding: 1rem; border-radius: 0.5rem; z-index: 9999; transform: translateY(100px); opacity: 0; transition: all 0.3s; }
#toast.show { transform: translateY(0); opacity: 1; }

.dropzone { border: 2px dashed var(--border); padding: 3rem; text-align: center; border-radius: 1rem; cursor: pointer; transition: background 0.2s; }
.dropzone.dragover { background: rgba(var(--primary-rgb), 0.1); border-color: var(--primary); }

.project-item { display: flex; justify-content: space-between; align-items: center; padding: 0.75rem; border-bottom: 1px solid var(--border); }
.project-item:hover { background: rgba(0,0,0,0.02); }
body.dark-mode .project-item:hover { background: rgba(255,255,255,0.02); }

.login-container { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: linear-gradient(135deg, #4F46E5 0%, #10B981 100%); }
.login-card { background: var(--surface); padding: 2.5rem; border-radius: 1rem; width: 100%; max-width: 400px; box-shadow: 0 20px 25px -5px rgba(0,0,0,0.1); }
.login-card h1 { text-align: center; margin-bottom: 1.5rem; color: var(--text); }
.alert { padding: 1rem; border-radius: 0.5rem; margin-bottom: 1rem; background: #FEF2F2; color: #991B1B; }